Nondisjunction, Genetic
Meiosis
Chromosomes, Human, Pair 21
Aneuploidy
Crossing Over, Genetic
Down Syndrome
Sex Chromosomes
Abnormalities, Radiation-Induced
Chromosomes
X Chromosome
Chromosome Aberrations
Recombination, Genetic
Y Chromosome
Crosses, Genetic
Potoroidae
Centromere
Chromosomes, Fungal
Mitosis
Chromatids
Translocation, Genetic
Secale cereale
Chromosome Mapping
Mosaicism
Diploidy
Genetic Techniques
Genetic Markers
Nucleolus Organizer Region
Chromosome Disorders
In Situ Hybridization, Fluorescence
Drosophila melanogaster
Sex Chromosome Aberrations
X-Rays
Chromosomes, Human, Pair 18
Spermatocytes
Metaphase
Mutagens
Chromosomes, Human, Pair 13
Oocytes
Hygromycin B
Phosphoribosylglycinamide Formyltransferase
Mutation
Sister Chromatid Exchange
Heterozygote
Synaptonemal Complex
Chromosome Breakage
Polyploidy
Monosomy
Chromosome Banding
Chromosomes, Plant
Spores
Spermatozoa
Anaphase
Zea mays
Drosophila
Germ-cell nondisjunction in testes biopsies of men with idiopathic infertility. (1/246)
Intracytoplasmic sperm injection (ICSI) has been used in combination with testicular sperm extraction to achieve pregnancies in couples with severe male-factor infertility, yet many of the underlying genetic mechanisms remain largely unknown. To investigate nondisjunction in mitotic and meiotic germ cells, we performed three-color FISH to detect numeric chromosome aberrations in testicular tissue samples from infertile men confirmed to have impaired spermatogenesis of unknown cause. FISH was employed to determine the rate of sex-chromosome aneuploidy in germ cells. Nuclei were distinguished as haploid or diploid, respectively. The overall incidence of sex-chromosome aneuploidy in germ cells was found to be significantly higher (P<.00001) in all three abnormal histopathologic patterns (range 39.0%-43.5%) as compared with normal controls (29.1%). The relative ratio of normal to aneuploid nuclei in the diploid cells of patients with impaired spermatogenesis was approximately 1.0, a >300% decrease when compared with the 4.42 ratio detected in patients with normal spermatogenesis. These results provide direct evidence of an increased incidence of sex-chromosome aneuploidy observed in germ cells of men with severely impaired spermatogenesis who might be candidates for ICSI with sperm obtained directly from the testis. The incidence of aneuploidy was significantly greater among the diploid nuclei, which suggests that chromosome instability is a result of altered genetic control during mitotic cell division and proliferation during spermatogenesis. (+info)Identification of novel Drosophila meiotic genes recovered in a P-element screen. (2/246)
The segregation of homologous chromosomes from one another is the essence of meiosis. In many organisms, accurate segregation is ensured by the formation of chiasmata resulting from crossing over. Drosophila melanogaster females use this type of recombination-based system, but they also have mechanisms for segregating achiasmate chromosomes with high fidelity. We describe a P-element mutagenesis and screen in a sensitized genetic background to detect mutations that impair meiotic chromosome pairing, recombination, or segregation. Our screen identified two new recombination-deficient mutations: mei-P22, which fully eliminates meiotic recombination, and mei-P26, which decreases meiotic exchange by 70% in a polar fashion. We also recovered an unusual allele of the ncd gene, whose wild-type product is required for proper structure and function of the meiotic spindle. However, the screen yielded primarily mutants specifically defective in the segregation of achiasmate chromosomes. Although most of these are alleles of previously undescribed genes, five were in the known genes alphaTubulin67C, CycE, push, and Trl. The five mutations in known genes produce novel phenotypes for those genes. (+info)Specific chromosome alterations in fluconazole-resistant mutants of Candida albicans. (3/246)
The exposure of Candida albicans to fluconazole resulted in the nondisjunction of two specific chromosomes in 17 drug-resistant mutants, each obtained by an independent mutational event. The chromosomal changes occurred at high frequencies and were related to the duration of the drug exposure. The loss of one homologue of chromosome 4 occurred after incubation on a fluconazole medium for 7 days. A second change, the gain of one copy of chromosome 3, was observed after exposure for 35 or 40 days. We found that the mRNA levels of ERG11, CDR1, CDR2, and MDR1, the candidate fluconazole resistance genes, remained either the same or were diminished. The lack of overexpression of putative drug pumps or the drug target indicated that some other mechanism(s) may be operating. The fluconazole resistance phenotype, electrophoretic karyotypes, and transcript levels of mutants were stable after growth for 112 generations in the absence of fluconazole. This is the first report to demonstrate that resistance to fluconazole can be dependent on chromosomal nondisjunction. Furthermore, we suggest that a low-level resistance to fluconazole arising during the early stages of clinical treatment may occur by this mechanism. These results support our earlier hypothesis that changes in C. albicans chromosome number is a common means to control a resource of potentially beneficial genes that are related to important cellular functions. (+info)Genetic variation in rates of nondisjunction: association of two naturally occurring polymorphisms in the chromokinesin nod with increased rates of nondisjunction in Drosophila melanogaster. (4/246)
Genetic variation in nondisjunction frequency among X chromosomes from two Drosophila melanogaster natural populations is examined in a sensitized assay. A high level of genetic variation is observed (a range of 0.006-0.241). Two naturally occurring variants at the nod locus, a chromokinesin required for proper achiasmate chromosome segregation, are significantly associated with an increased frequency of nondisjunction. Both of these polymorphisms are found at intermediate frequency in widely distributed natural populations. To account for these observations, we propose a general model incorporating unique opportunities for meiotic drive during female meiosis. The ootid competition model can account for both high mean rates of female-specific nondisjunction in Drosophila and humans as well as the standing genetic variation in this critical fitness character in natural populations. (+info)New yeast genes important for chromosome integrity and segregation identified by dosage effects on genome stability. (5/246)
Phenotypes produced by gene overexpression may provide important clues to gene function. Here, we have performed a search for genes that affect chromo-some stability when overexpressed in the budding yeast Saccharomyces cerevisiae. We have obtained clones encompassing 30 different genes. Twenty-four of these genes have been previously characterized. Most of them are involved in chromatin dynamics, cell cycle control, DNA replication or mitotic chromosome segregation. Six novel genes obtained in this screen were named CST (chromosome stability). Based on the pattern of genomic instability, inter-action with checkpoint mutations and sensitivity to chromosome replication or segregation inhibitors, we conclude that overexpression of CST4 specifically interferes with mitotic chromosome segregation, and CST6 affects some aspect of DNA metabolism. The other CST genes had complex pleiotropic phenotypes. We have created deletions of five genes obtained in this screen, CST9, CST13, NAT1, SBA1 and FUN30. None of these genes is essential for viability, and deletions of NAT1 and SBA1 cause chromosome instability, a phenotype not previously associated with these genes. This work shows that analysis of dosage effects is complementary to mutational analysis of chromosome transmission fidelity, as it allows the identification of chromosome stability genes that have not been detected in mutational screens. (+info)Centromere mapping functions for aneuploid meiotic products: Analysis of rec8, rec10 and rec11 mutants of the fission yeast Schizosaccharomyces pombe. (6/246)
Recent evidence suggests that the position of reciprocal recombination events (crossovers) is important for the segregation of homologous chromosomes during meiosis I and sister chromatids during meiosis II. We developed genetic mapping functions that permit the simultaneous analysis of centromere-proximal crossover recombination and the type of segregation error leading to aneuploidy. The mapping functions were tested in a study of the rec8, rec10, and rec11 mutants of fission yeast. In each mutant we monitored each of the three chromosome pairs. Between 38 and 100% of the chromosome segregation errors in the rec8 mutants were due to meiosis I nondisjunction of homologous chromosomes. The remaining segregation errors were likely the result of precocious separation of sister chromatids, a previously described defect in the rec8 mutants. Between 47 and 100% of segregation errors in the rec10 and rec11 mutants were due to nondisjunction of sister chromatids during meiosis II. In addition, centromere-proximal recombination was reduced as much as 14-fold or more on chromosomes that had experienced nondisjunction. These results demonstrate the utility of the new mapping functions and support models in which sister chromatid cohesion and crossover position are important determinants for proper chromosome segregation in each meiotic division. (+info)Analysis of chromosome loss and non-disjunction in cytokinesis-blocked lymphocytes of 24 male subjects. (7/246)
Chromosome malsegregation in peripheral blood lymphocytes of 24 healthy male subjects was analysed by means of fluorescence in situ hybridization with centromeric probes of chromosomes 7, 11, 18 and X. On the basis of the distribution of centromeric signals in cytokinesis-blocked cells, both loss (leading to centromere-positive micronuclei) and non-disjunction (resulting in an unbalanced distribution of signals in the main nuclei) of the hybridized chromosomes in vitro were identified. In addition, the incidence of binucleated cells with two hyperploid nuclei, possibly arising from mitotic division of trisomic types, was determined. In this way, the incidence of chromosome malsegregation in vivo and in vitro could be compared in the same cell samples. The results obtained show that ageing is positively correlated with the incidence of malsegregation of chromosome X in peripheral lymphocytes of male subjects and confirm the higher susceptibility of chromosome X to malsegregation in comparison with autosomes. A positive correlation between in vitro and in vivo malsegregation rates was observed for both chromosome X and for autosomes. Finally, relatively high frequencies of multiple malsegregation events, greater than expected for independent events, were recorded for both chromosome X and for autosomes, indicating that the abnormal segregation of chromosomes may be connected to a general dysfunction of the mitotic apparatus. The correlation observed between in vitro and in vivo malsegregation frequencies and the association of both parameters with ageing suggest that analysis of chromosome malsegregation in binucleated cells is a useful tool in the study of genomic instability in human populations. (+info)Maternal uniparental disomy for chromosome 14 in a boy with a normal karyotype. (8/246)
We report on a boy with a maternal uniparental disomy for chromosome 14 (UPD(14)). At 7 years of age he was referred to us by the paediatrician because of symptoms of Prader-Willi syndrome (PWS). He showed short stature, obesity, mild developmental delay, cryptorchidism, and some mild dysmorphic features. The history further indicated intrauterine growth retardation at the end of the pregnancy. His mother was 44 years of age at the time of his birth. After birth he showed hypotonia with poor sucking, for which gavage feeding was needed. Motor development was delayed. After 1 year he became obese despite a normal appetite. Recurrent middle ear infections, a high pain threshold, and a great skill with jigsaw puzzles were reported. There were no behavioural problems or sleep disturbance. Chromosomal analysis was normal (46,XY). DNA analysis for Prader-Willi syndrome showed no abnormalities. Two years later he was re-examined because we thought his features fitted the PWS-like phenotype associated with maternal UPD(14). At that time precocious puberty was evident. DNA analysis showed maternal heterodisomy for chromosome 14. In all the previously described 11 cases with maternal UPD(14), a Robertsonian translocation involving chromosome 14 was detected cytogenetically before DNA analysis. This is the first report of diagnosis of maternal UPD(14) based on clinical features. This finding underlines the importance of DNA analysis for maternal UPD(14) in patients with a similar PWS-like phenotype even without previous identification of a Robertsonian translocation involving chromosome 14. (+info)Nondisjunction is a genetic term that refers to the failure of homologous chromosomes or sister chromatids to properly separate during cell division, resulting in an abnormal number of chromosomes in the daughter cells. This can occur during either mitosis (resulting in somatic mutations) or meiosis (leading to gametes with an incorrect number of chromosomes).
In humans, nondisjunction of chromosome 21 during meiosis is the most common cause of Down syndrome, resulting in three copies of chromosome 21 (trisomy 21) in the affected individual. Nondisjunction can also result in other aneuploidies, such as Turner syndrome (X monosomy), Klinefelter syndrome (XXY), and Edwards syndrome (trisomy 18).
Nondisjunction is typically a random event, although maternal age has been identified as a risk factor for nondisjunction during meiosis. In some cases, structural chromosomal abnormalities or genetic factors may predispose an individual to nondisjunction events.
Meiosis is a type of cell division that results in the formation of four daughter cells, each with half the number of chromosomes as the parent cell. It is a key process in sexual reproduction, where it generates gametes or sex cells (sperm and eggs).
The process of meiosis involves one round of DNA replication followed by two successive nuclear divisions, meiosis I and meiosis II. In meiosis I, homologous chromosomes pair, form chiasma and exchange genetic material through crossing over, then separate from each other. In meiosis II, sister chromatids separate, leading to the formation of four haploid cells. This process ensures genetic diversity in offspring by shuffling and recombining genetic information during the formation of gametes.
Human chromosome pair 21 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each member of the pair is a single chromosome, and they are identical to each other. Chromosomes are made up of DNA, which contains genetic information that determines many of an individual's traits and characteristics.
Chromosome pair 21 is one of the 23 pairs of human autosomal chromosomes, meaning they are not sex chromosomes (X or Y). Chromosome pair 21 is the smallest of the human chromosomes, and it contains approximately 48 million base pairs of DNA. It contains around 200-300 genes that provide instructions for making proteins and regulating various cellular processes.
Down syndrome, a genetic disorder characterized by intellectual disability, developmental delays, distinct facial features, and sometimes heart defects, is caused by an extra copy of chromosome pair 21 or a part of it. This additional genetic material can lead to abnormalities in brain development and function, resulting in the characteristic symptoms of Down syndrome.
Aneuploidy is a medical term that refers to an abnormal number of chromosomes in a cell. Chromosomes are thread-like structures located inside the nucleus of cells that contain genetic information in the form of genes.
In humans, the normal number of chromosomes in a cell is 46, arranged in 23 pairs. Aneuploidy occurs when there is an extra or missing chromosome in one or more of these pairs. For example, Down syndrome is a condition that results from an extra copy of chromosome 21, also known as trisomy 21.
Aneuploidy can arise during the formation of gametes (sperm or egg cells) due to errors in the process of cell division called meiosis. These errors can result in eggs or sperm with an abnormal number of chromosomes, which can then lead to aneuploidy in the resulting embryo.
Aneuploidy is a significant cause of birth defects and miscarriages. The severity of the condition depends on which chromosomes are affected and the extent of the abnormality. In some cases, aneuploidy may have no noticeable effects, while in others it can lead to serious health problems or developmental delays.
Crossing over, genetic is a process that occurs during meiosis, where homologous chromosomes exchange genetic material with each other. It is a crucial mechanism for generating genetic diversity in sexually reproducing organisms.
Here's a more detailed explanation:
During meiosis, homologous chromosomes pair up and align closely with each other. At this point, sections of the chromosomes can break off and reattach to the corresponding section on the homologous chromosome. This exchange of genetic material is called crossing over or genetic recombination.
The result of crossing over is that the two resulting chromosomes are no longer identical to each other or to the original chromosomes. Instead, they contain a unique combination of genetic material from both parents. Crossing over can lead to new combinations of alleles (different forms of the same gene) and can increase genetic diversity in the population.
Crossing over is a random process, so the location and frequency of crossover events vary between individuals and between chromosomes. The number and position of crossovers can affect the likelihood that certain genes will be inherited together or separated, which is an important consideration in genetic mapping and breeding studies.
Down syndrome is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is characterized by intellectual and developmental disabilities, distinctive facial features, and sometimes physical growth delays and health problems. The condition affects approximately one in every 700 babies born in the United States.
Individuals with Down syndrome have varying degrees of cognitive impairment, ranging from mild to moderate or severe. They may also have delayed development, including late walking and talking, and may require additional support and education services throughout their lives.
People with Down syndrome are at increased risk for certain health conditions, such as congenital heart defects, respiratory infections, hearing loss, vision problems, gastrointestinal issues, and thyroid disorders. However, many individuals with Down syndrome live healthy and fulfilling lives with appropriate medical care and support.
The condition is named after John Langdon Down, an English physician who first described the syndrome in 1866.
Trisomy is a genetic condition where there is an extra copy of a particular chromosome, resulting in 47 chromosomes instead of the typical 46 in a cell. This usually occurs due to an error in cell division during the development of the egg, sperm, or embryo.
Instead of the normal pair, there are three copies (trisomy) of that chromosome. The most common form of trisomy is Trisomy 21, also known as Down syndrome, where there is an extra copy of chromosome 21. Other forms include Trisomy 13 (Patau syndrome) and Trisomy 18 (Edwards syndrome), which are associated with more severe developmental issues and shorter lifespans.
Trisomy can also occur in a mosaic form, where some cells have the extra chromosome while others do not, leading to varying degrees of symptoms depending on the proportion of affected cells.
Sex chromosomes, often denoted as X and Y, are one of the 23 pairs of human chromosomes found in each cell of the body. Normally, females have two X chromosomes (46,XX), and males have one X and one Y chromosome (46,XY). The sex chromosomes play a significant role in determining the sex of an individual. They contain genes that contribute to physical differences between men and women. Any variations or abnormalities in the number or structure of these chromosomes can lead to various genetic disorders and conditions related to sexual development and reproduction.
Radiation-induced abnormalities refer to changes in tissues, organs, or bodily functions that are caused by exposure to radiation. These abnormalities can occur as a result of therapeutic radiation used in cancer treatment or from exposure to high levels of ionizing radiation in diagnostic procedures or environmental settings.
The severity and type of radiation-induced abnormalities depend on several factors, including the dose and duration of radiation exposure, the part of the body that was exposed, and the individual's sensitivity to radiation. Some common radiation-induced abnormalities include:
1. Radiation sickness: This is a set of symptoms that occur after exposure to high levels of ionizing radiation. Symptoms can include nausea, vomiting, diarrhea, fatigue, and fever.
2. Skin damage: Radiation can cause skin redness, blistering, and peeling, especially in areas where the radiation was focused.
3. Cataracts: Exposure to high levels of radiation can cause cataracts, which are cloudy areas that develop in the lens of the eye.
4. Infertility: Radiation exposure can damage the reproductive organs and lead to infertility in both men and women.
5. Increased risk of cancer: Exposure to radiation can increase the risk of developing certain types of cancer, such as leukemia and thyroid cancer.
6. Damage to the nervous system: High levels of radiation exposure can cause damage to the nervous system, leading to symptoms such as headaches, seizures, and confusion.
7. Genetic mutations: Radiation exposure can cause genetic mutations that can be passed down to future generations.
It is important to note that the risk of developing radiation-induced abnormalities depends on many factors, including the dose and duration of radiation exposure, the individual's sensitivity to radiation, and their overall health status. If you have concerns about radiation exposure or radiation-induced abnormalities, it is best to speak with a healthcare professional.
Chromosomes are thread-like structures that exist in the nucleus of cells, carrying genetic information in the form of genes. They are composed of DNA and proteins, and are typically present in pairs in the nucleus, with one set inherited from each parent. In humans, there are 23 pairs of chromosomes for a total of 46 chromosomes. Chromosomes come in different shapes and forms, including sex chromosomes (X and Y) that determine the biological sex of an individual. Changes or abnormalities in the number or structure of chromosomes can lead to genetic disorders and diseases.
Chromosome segregation is the process that occurs during cell division (mitosis or meiosis) where replicated chromosomes are separated and distributed equally into two daughter cells. Each chromosome consists of two sister chromatids, which are identical copies of genetic material. During chromosome segregation, these sister chromatids are pulled apart by a structure called the mitotic spindle and moved to opposite poles of the cell. This ensures that each new cell receives one copy of each chromosome, preserving the correct number and composition of chromosomes in the organism.
The X chromosome is one of the two types of sex-determining chromosomes in humans (the other being the Y chromosome). It's one of the 23 pairs of chromosomes that make up a person's genetic material. Females typically have two copies of the X chromosome (XX), while males usually have one X and one Y chromosome (XY).
The X chromosome contains hundreds of genes that are responsible for the production of various proteins, many of which are essential for normal bodily functions. Some of the critical roles of the X chromosome include:
1. Sex Determination: The presence or absence of the Y chromosome determines whether an individual is male or female. If there is no Y chromosome, the individual will typically develop as a female.
2. Genetic Disorders: Since females have two copies of the X chromosome, they are less likely to be affected by X-linked genetic disorders than males. Males, having only one X chromosome, will express any recessive X-linked traits they inherit.
3. Dosage Compensation: To compensate for the difference in gene dosage between males and females, a process called X-inactivation occurs during female embryonic development. One of the two X chromosomes is randomly inactivated in each cell, resulting in a single functional copy per cell.
The X chromosome plays a crucial role in human genetics and development, contributing to various traits and characteristics, including sex determination and dosage compensation.
Maternal age is a term used to describe the age of a woman at the time she becomes pregnant or gives birth. It is often used in medical and epidemiological contexts to discuss the potential risks, complications, and outcomes associated with pregnancy and childbirth at different stages of a woman's reproductive years.
Advanced maternal age typically refers to women who become pregnant or give birth at 35 years of age or older. This group faces an increased risk for certain chromosomal abnormalities, such as Down syndrome, and other pregnancy-related complications, including gestational diabetes, preeclampsia, and cesarean delivery.
On the other end of the spectrum, adolescent pregnancies (those that occur in women under 20 years old) also come with their own set of potential risks and complications, such as preterm birth, low birth weight, and anemia.
It's important to note that while maternal age can influence pregnancy outcomes, many other factors – including genetics, lifestyle choices, and access to quality healthcare – can also play a significant role in determining the health of both mother and baby during pregnancy and childbirth.
Chromosome aberrations refer to structural and numerical changes in the chromosomes that can occur spontaneously or as a result of exposure to mutagenic agents. These changes can affect the genetic material encoded in the chromosomes, leading to various consequences such as developmental abnormalities, cancer, or infertility.
Structural aberrations include deletions, duplications, inversions, translocations, and rings, which result from breaks and rearrangements of chromosome segments. Numerical aberrations involve changes in the number of chromosomes, such as aneuploidy (extra or missing chromosomes) or polyploidy (multiples of a complete set of chromosomes).
Chromosome aberrations can be detected and analyzed using various cytogenetic techniques, including karyotyping, fluorescence in situ hybridization (FISH), and comparative genomic hybridization (CGH). These methods allow for the identification and characterization of chromosomal changes at the molecular level, providing valuable information for genetic counseling, diagnosis, and research.
Genetic recombination is the process by which genetic material is exchanged between two similar or identical molecules of DNA during meiosis, resulting in new combinations of genes on each chromosome. This exchange occurs during crossover, where segments of DNA are swapped between non-sister homologous chromatids, creating genetic diversity among the offspring. It is a crucial mechanism for generating genetic variability and facilitating evolutionary change within populations. Additionally, recombination also plays an essential role in DNA repair processes through mechanisms such as homologous recombinational repair (HRR) and non-homologous end joining (NHEJ).
The Y chromosome is one of the two sex-determining chromosomes in humans and many other animals, along with the X chromosome. The Y chromosome contains the genetic information that helps to determine an individual's sex as male. It is significantly smaller than the X chromosome and contains fewer genes.
The Y chromosome is present in males, who inherit it from their father. Females, on the other hand, have two X chromosomes, one inherited from each parent. The Y chromosome includes a gene called SRY (sex-determining region Y), which initiates the development of male sexual characteristics during embryonic development.
It is worth noting that the Y chromosome has a relatively high rate of genetic mutation and degeneration compared to other chromosomes, leading to concerns about its long-term viability in human evolution. However, current evidence suggests that the Y chromosome has been stable for at least the past 25 million years.
"Genetic crosses" refer to the breeding of individuals with different genetic characteristics to produce offspring with specific combinations of traits. This process is commonly used in genetics research to study the inheritance patterns and function of specific genes.
There are several types of genetic crosses, including:
1. Monohybrid cross: A cross between two individuals that differ in the expression of a single gene or trait.
2. Dihybrid cross: A cross between two individuals that differ in the expression of two genes or traits.
3. Backcross: A cross between an individual from a hybrid population and one of its parental lines.
4. Testcross: A cross between an individual with unknown genotype and a homozygous recessive individual.
5. Reciprocal cross: A cross in which the male and female parents are reversed to determine if there is any effect of sex on the expression of the trait.
These genetic crosses help researchers to understand the mode of inheritance, linkage, recombination, and other genetic phenomena.
I'm sorry for any confusion, but "Potoroidae" is not a medical term. It is a taxonomic family within the order Diprotodontia, which includes several species of rat-kangaroos that are native to Australia. These small marsupials are known for their hopping locomotion and nocturnal behavior. If you have any questions about veterinary or medical terminology, I would be happy to help with those!
A centromere is a specialized region found on chromosomes that plays a crucial role in the separation of replicated chromosomes during cell division. It is the point where the sister chromatids (the two copies of a chromosome formed during DNA replication) are joined together. The centromere contains highly repeated DNA sequences and proteins that form a complex structure known as the kinetochore, which serves as an attachment site for microtubules of the mitotic spindle during cell division.
During mitosis or meiosis, the kinetochore facilitates the movement of chromosomes by interacting with the microtubules, allowing for the accurate distribution of genetic material to the daughter cells. Centromeres can vary in their position and structure among different species, ranging from being located near the middle of the chromosome (metacentric) to being positioned closer to one end (acrocentric). The precise location and characteristics of centromeres are essential for proper chromosome segregation and maintenance of genomic stability.
Chromosomes in fungi are thread-like structures that contain genetic material, composed of DNA and proteins, present in the nucleus of a cell. Unlike humans and other eukaryotes that have a diploid number of chromosomes in their somatic cells, fungal chromosome numbers can vary widely between and within species.
Fungal chromosomes are typically smaller and fewer in number compared to those found in plants and animals. The chromosomal organization in fungi is also different from other eukaryotes. In many fungi, the chromosomes are condensed throughout the cell cycle, whereas in other eukaryotes, chromosomes are only condensed during cell division.
Fungi can have linear or circular chromosomes, depending on the species. For example, the model organism Saccharomyces cerevisiae (budding yeast) has a set of 16 small circular chromosomes, while other fungi like Neurospora crassa (red bread mold) and Aspergillus nidulans (a filamentous fungus) have linear chromosomes.
Fungal chromosomes play an essential role in the growth, development, reproduction, and survival of fungi. They carry genetic information that determines various traits such as morphology, metabolism, pathogenicity, and resistance to environmental stresses. Advances in genomic technologies have facilitated the study of fungal chromosomes, leading to a better understanding of their structure, function, and evolution.
Mitosis is a type of cell division in which the genetic material of a single cell, called the mother cell, is equally distributed into two identical daughter cells. It's a fundamental process that occurs in multicellular organisms for growth, maintenance, and repair, as well as in unicellular organisms for reproduction.
The process of mitosis can be broken down into several stages: prophase, prometaphase, metaphase, anaphase, and telophase. During prophase, the chromosomes condense and become visible, and the nuclear envelope breaks down. In prometaphase, the nuclear membrane is completely disassembled, and the mitotic spindle fibers attach to the chromosomes at their centromeres.
During metaphase, the chromosomes align at the metaphase plate, an imaginary line equidistant from the two spindle poles. In anaphase, sister chromatids are pulled apart by the spindle fibers and move toward opposite poles of the cell. Finally, in telophase, new nuclear envelopes form around each set of chromosomes, and the chromosomes decondense and become less visible.
Mitosis is followed by cytokinesis, a process that divides the cytoplasm of the mother cell into two separate daughter cells. The result of mitosis and cytokinesis is two genetically identical cells, each with the same number and kind of chromosomes as the original parent cell.
Chromatids are defined as the individual strands that make up a duplicated chromosome. They are formed during the S phase of the cell cycle, when replication occurs and each chromosome is copied, resulting in two identical sister chromatids. These chromatids are connected at a region called the centromere and are held together by cohesin protein complexes until they are separated during mitosis or meiosis.
During mitosis, the sister chromatids are pulled apart by the mitotic spindle apparatus and distributed equally to each daughter cell. In meiosis, which is a type of cell division that occurs in the production of gametes (sex cells), homologous chromosomes pair up and exchange genetic material through a process called crossing over. After crossing over, each homologous chromosome consists of two recombinant chromatids that are separated during meiosis I, and then sister chromatids are separated during meiosis II.
Chromatids play an essential role in the faithful transmission of genetic information from one generation to the next, ensuring that each daughter cell or gamete receives a complete set of chromosomes with intact and functional genes.
Translocation, genetic, refers to a type of chromosomal abnormality in which a segment of a chromosome is transferred from one chromosome to another, resulting in an altered genome. This can occur between two non-homologous chromosomes (non-reciprocal translocation) or between two homologous chromosomes (reciprocal translocation). Genetic translocations can lead to various clinical consequences, depending on the genes involved and the location of the translocation. Some translocations may result in no apparent effects, while others can cause developmental abnormalities, cancer, or other genetic disorders. In some cases, translocations can also increase the risk of having offspring with genetic conditions.
"Secale cereale" is the scientific name for a type of grass that is more commonly known as rye or ergot. It is often used as a food grain and also in the production of certain medicines. However, it's worth noting that ergot, which is a fungus that infects rye and other grains, can produce harmful compounds that can cause serious health problems if ingested. Therefore, it's important to handle and consume rye grain properly to avoid any potential risks.
Chromosome mapping, also known as physical mapping, is the process of determining the location and order of specific genes or genetic markers on a chromosome. This is typically done by using various laboratory techniques to identify landmarks along the chromosome, such as restriction enzyme cutting sites or patterns of DNA sequence repeats. The resulting map provides important information about the organization and structure of the genome, and can be used for a variety of purposes, including identifying the location of genes associated with genetic diseases, studying evolutionary relationships between organisms, and developing genetic markers for use in breeding or forensic applications.
Chromosomes in insects are thread-like structures that contain genetic material, made up of DNA and proteins, found in the nucleus of a cell. In insects, like other eukaryotes, chromosomes come in pairs, with one set inherited from each parent. They are crucial for the inheritance, storage, and transmission of genetic information from one generation to the next.
Insects typically have a diploid number of chromosomes (2n), which varies among species. The chromosomes are present in the cell's nucleus during interphase as loosely coiled structures called chromatin. During cell division, they condense and become visible under the microscope as distinct, X-shaped structures called metaphase chromosomes.
The insect chromosome set includes autosomal chromosomes, which are identical in appearance and function between males and females, and sex chromosomes, which differ between males and females. In many insects, the males have an XY sex chromosome constitution, while the females have an XX sex chromosome constitution. The sex chromosomes carry genes that determine the sex of the individual.
Insect chromosomes play a vital role in various biological processes, including development, reproduction, and evolution. They are also essential for genetic research and breeding programs in agriculture and medicine.
Mosaicism, in the context of genetics and medicine, refers to the presence of two or more cell lines with different genetic compositions in an individual who has developed from a single fertilized egg. This means that some cells have one genetic makeup, while others have a different genetic makeup. This condition can occur due to various reasons such as errors during cell division after fertilization.
Mosaicism can involve chromosomes (where whole or parts of chromosomes are present in some cells but not in others) or it can involve single genes (where a particular gene is present in one form in some cells and a different form in others). The symptoms and severity of mosaicism can vary widely, depending on the type and location of the genetic difference and the proportion of cells that are affected. Some individuals with mosaicism may not experience any noticeable effects, while others may have significant health problems.
Diploidy is a term used in genetics to describe the state of having two sets of chromosomes in each cell. In diploid organisms, one set of chromosomes is inherited from each parent, resulting in a total of 2 sets of chromosomes.
In humans, for example, most cells are diploid and contain 46 chromosomes arranged in 23 pairs. This includes 22 pairs of autosomal chromosomes and one pair of sex chromosomes (XX in females or XY in males). Diploidy is a characteristic feature of many complex organisms, including animals, plants, and fungi.
Diploid cells can undergo a process called meiosis, which results in the formation of haploid cells that contain only one set of chromosomes. These haploid cells can then combine with other haploid cells during fertilization to form a new diploid organism.
Abnormalities in diploidy can lead to genetic disorders, such as Down syndrome, which occurs when an individual has three copies of chromosome 21 instead of the typical two. This extra copy of the chromosome can result in developmental delays and intellectual disabilities.
Genetic techniques refer to a variety of methods and tools used in the field of genetics to study, manipulate, and understand genes and their functions. These techniques can be broadly categorized into those that allow for the identification and analysis of specific genes or genetic variations, and those that enable the manipulation of genes in order to understand their function or to modify them for therapeutic purposes.
Some examples of genetic analysis techniques include:
1. Polymerase Chain Reaction (PCR): a method used to amplify specific DNA sequences, allowing researchers to study small amounts of DNA.
2. Genome sequencing: the process of determining the complete DNA sequence of an organism's genome.
3. Genotyping: the process of identifying and analyzing genetic variations or mutations in an individual's DNA.
4. Linkage analysis: a method used to identify genetic loci associated with specific traits or diseases by studying patterns of inheritance within families.
5. Expression profiling: the measurement of gene expression levels in cells or tissues, often using microarray technology.
Some examples of genetic manipulation techniques include:
1. Gene editing: the use of tools such as CRISPR-Cas9 to modify specific genes or genetic sequences.
2. Gene therapy: the introduction of functional genes into cells or tissues to replace missing or nonfunctional genes.
3. Transgenic technology: the creation of genetically modified organisms (GMOs) by introducing foreign DNA into their genomes.
4. RNA interference (RNAi): the use of small RNA molecules to silence specific genes and study their function.
5. Induced pluripotent stem cells (iPSCs): the creation of stem cells from adult cells through genetic reprogramming, allowing for the study of development and disease in vitro.
"Paternal age" is a term used to describe the age of a father at the time of conception. It is often considered in relation to the potential impact on genetic health and the risk of certain genetic conditions in offspring. As a father's age increases, there is a higher chance of mutations occurring during the formation of sperm cells, which can potentially lead to an increased risk of certain genetic disorders such as Apert syndrome, Crouzon syndrome, and Schinzel-Giedion midface retraction syndrome. However, it is important to note that while the risk does increase with paternal age, the overall likelihood remains relatively low.
Genetic markers are specific segments of DNA that are used in genetic mapping and genotyping to identify specific genetic locations, diseases, or traits. They can be composed of short tandem repeats (STRs), single nucleotide polymorphisms (SNPs), restriction fragment length polymorphisms (RFLPs), or variable number tandem repeats (VNTRs). These markers are useful in various fields such as genetic research, medical diagnostics, forensic science, and breeding programs. They can help to track inheritance patterns, identify genetic predispositions to diseases, and solve crimes by linking biological evidence to suspects or victims.
The Nucleolus Organizer Region (NOR) is a specific region within the chromosomes, primarily in the short arm of the acrocentric chromosomes (chromosomes 13, 14, 15, 21, and 22). It consists of clusters of repetitive DNA sequences that encode ribosomal RNA (rRNA) genes. During interphase, these regions form the nucleolus, a distinct structure within the nucleus where rRNA transcription, processing, and ribosome assembly occur. The number of NORs in an individual can vary, which has implications in certain genetic conditions and aging processes.
Chromosome disorders are a group of genetic conditions caused by abnormalities in the number or structure of chromosomes. Chromosomes are thread-like structures located in the nucleus of cells that contain most of the body's genetic material, which is composed of DNA and proteins. Normally, humans have 23 pairs of chromosomes, for a total of 46 chromosomes.
Chromosome disorders can result from changes in the number of chromosomes (aneuploidy) or structural abnormalities in one or more chromosomes. Some common examples of chromosome disorders include:
1. Down syndrome: a condition caused by an extra copy of chromosome 21, resulting in intellectual disability, developmental delays, and distinctive physical features.
2. Turner syndrome: a condition that affects only females and is caused by the absence of all or part of one X chromosome, resulting in short stature, lack of sexual development, and other symptoms.
3. Klinefelter syndrome: a condition that affects only males and is caused by an extra copy of the X chromosome, resulting in tall stature, infertility, and other symptoms.
4. Cri-du-chat syndrome: a condition caused by a deletion of part of the short arm of chromosome 5, resulting in intellectual disability, developmental delays, and a distinctive cat-like cry.
5. Fragile X syndrome: a condition caused by a mutation in the FMR1 gene on the X chromosome, resulting in intellectual disability, behavioral problems, and physical symptoms.
Chromosome disorders can be diagnosed through various genetic tests, such as karyotyping, chromosomal microarray analysis (CMA), or fluorescence in situ hybridization (FISH). Treatment for these conditions depends on the specific disorder and its associated symptoms and may include medical interventions, therapies, and educational support.
Karyotyping is a medical laboratory test used to study the chromosomes in a cell. It involves obtaining a sample of cells from a patient, usually from blood or bone marrow, and then staining the chromosomes so they can be easily seen under a microscope. The chromosomes are then arranged in pairs based on their size, shape, and other features to create a karyotype. This visual representation allows for the identification and analysis of any chromosomal abnormalities, such as extra or missing chromosomes, or structural changes like translocations or inversions. These abnormalities can provide important information about genetic disorders, diseases, and developmental problems.
In situ hybridization, fluorescence (FISH) is a type of molecular cytogenetic technique used to detect and localize the presence or absence of specific DNA sequences on chromosomes through the use of fluorescent probes. This technique allows for the direct visualization of genetic material at a cellular level, making it possible to identify chromosomal abnormalities such as deletions, duplications, translocations, and other rearrangements.
The process involves denaturing the DNA in the sample to separate the double-stranded molecules into single strands, then adding fluorescently labeled probes that are complementary to the target DNA sequence. The probe hybridizes to the complementary sequence in the sample, and the location of the probe is detected by fluorescence microscopy.
FISH has a wide range of applications in both clinical and research settings, including prenatal diagnosis, cancer diagnosis and monitoring, and the study of gene expression and regulation. It is a powerful tool for identifying genetic abnormalities and understanding their role in human disease.
P-Fluorophenylalanine (p-FPA) is not a medical term, but a chemical compound used in research and medical fields. It's a type of amino acid that is used as a building block for proteins, similar to the naturally occurring amino acid phenylalanine. However, p-FPA has a fluorine atom attached to its para position (one of the possible positions on the phenyl ring).
This compound can be used in various research applications, including the study of protein synthesis and enzyme function. It's also been explored as a potential therapeutic agent for certain medical conditions, such as cancer and neurological disorders. However, more research is needed to establish its safety and efficacy for these uses.
'Drosophila melanogaster' is the scientific name for a species of fruit fly that is commonly used as a model organism in various fields of biological research, including genetics, developmental biology, and evolutionary biology. Its small size, short generation time, large number of offspring, and ease of cultivation make it an ideal subject for laboratory studies. The fruit fly's genome has been fully sequenced, and many of its genes have counterparts in the human genome, which facilitates the understanding of genetic mechanisms and their role in human health and disease.
Here is a brief medical definition:
Drosophila melanogaster (droh-suh-fih-luh meh-lon-guh-ster): A species of fruit fly used extensively as a model organism in genetic, developmental, and evolutionary research. Its genome has been sequenced, revealing many genes with human counterparts, making it valuable for understanding genetic mechanisms and their role in human health and disease.
Sex chromosome aberrations refer to structural and numerical abnormalities in the sex chromosomes, which are typically represented as X and Y chromosomes in humans. These aberrations can result in variations in the number of sex chromosomes, such as Klinefelter syndrome (47,XXY), Turner syndrome (45,X), and Jacobs/XYY syndrome (47,XYY). They can also include structural changes, such as deletions, duplications, or translocations of sex chromosome material.
Sex chromosome aberrations may lead to a range of phenotypic effects, including differences in physical characteristics, cognitive development, fertility, and susceptibility to certain health conditions. The manifestation and severity of these impacts can vary widely depending on the specific type and extent of the aberration, as well as individual genetic factors and environmental influences.
It is important to note that while sex chromosome aberrations may pose challenges and require medical management, they do not inherently define or limit a person's potential, identity, or worth. Comprehensive care, support, and education can help individuals with sex chromosome aberrations lead fulfilling lives and reach their full potential.
X-rays, also known as radiographs, are a type of electromagnetic radiation with higher energy and shorter wavelength than visible light. In medical imaging, X-rays are used to produce images of the body's internal structures, such as bones and organs, by passing the X-rays through the body and capturing the resulting shadows or patterns on a specialized film or digital detector.
The amount of X-ray radiation used is carefully controlled to minimize exposure and ensure patient safety. Different parts of the body absorb X-rays at different rates, allowing for contrast between soft tissues and denser structures like bone. This property makes X-rays an essential tool in diagnosing and monitoring a wide range of medical conditions, including fractures, tumors, infections, and foreign objects within the body.
Human chromosome pair 18 consists of two rod-shaped structures present in the nucleus of each cell of the human body. Chromosomes are made up of DNA, protein, and RNA, and they carry genetic information that determines an individual's physical characteristics, biochemical processes, and susceptibility to disease.
Chromosome pair 18 is one of the 23 pairs of chromosomes that make up the human genome. Each member of chromosome pair 18 has a length of about 75 million base pairs and contains around 600 genes. Chromosome pair 18 is also known as the "smart chromosome" because it contains many genes involved in brain development, function, and cognition.
Abnormalities in chromosome pair 18 can lead to genetic disorders such as Edwards syndrome (trisomy 18), in which there is an extra copy of chromosome 18, or deletion of a portion of the chromosome, leading to various developmental and cognitive impairments.
Spermatocytes are a type of cell that is involved in the process of spermatogenesis, which is the formation of sperm in the testes. Specifically, spermatocytes are the cells that undergo meiosis, a special type of cell division that results in the production of four haploid daughter cells, each containing half the number of chromosomes as the parent cell.
There are two types of spermatocytes: primary and secondary. Primary spermatocytes are diploid cells that contain 46 chromosomes (23 pairs). During meiosis I, these cells undergo a process called crossing over, in which genetic material is exchanged between homologous chromosomes. After crossing over, the primary spermatocytes divide into two secondary spermatocytes, each containing 23 chromosomes (but still with 23 pairs).
Secondary spermatocytes then undergo meiosis II, which results in the formation of four haploid spermatids. Each spermatid contains 23 single chromosomes and will eventually develop into a mature sperm cell through a process called spermiogenesis.
It's worth noting that spermatocytes are only found in males, as they are specific to the male reproductive system.
Metaphase is a phase in the cell division process (mitosis or meiosis) where the chromosomes align in the middle of the cell, also known as the metaphase plate or equatorial plane. During this stage, each chromosome consists of two sister chromatids attached to each other by a protein complex called the centromere. The spindle fibers from opposite poles of the cell attach to the centromeres of each chromosome, and through a process called congression, they align the chromosomes in the middle of the cell. This alignment allows for accurate segregation of genetic material during the subsequent anaphase stage.
Mutagens are physical or chemical agents that can cause permanent changes in the structure of genetic material, including DNA and chromosomes, leading to mutations. These mutations can be passed down to future generations and may increase the risk of cancer and other diseases. Examples of mutagens include ultraviolet (UV) radiation, tobacco smoke, and certain chemicals found in industrial settings. It is important to note that not all mutations are harmful, but some can have negative effects on health and development.
Human chromosome pair 13 consists of two rod-shaped structures present in the nucleus of each cell in the human body. Each chromosome is made up of DNA tightly coiled around histone proteins, forming a complex structure called a chromatin.
Chromosomes carry genetic information in the form of genes, which are sequences of DNA that code for specific traits and functions. Human cells typically have 23 pairs of chromosomes, for a total of 46 chromosomes. Chromosome pair 13 is one of the autosomal pairs, meaning it is not a sex chromosome (X or Y).
Chromosome pair 13 contains several important genes that are associated with various genetic disorders, such as cri-du-chat syndrome and Phelan-McDermid syndrome. Cri-du-chat syndrome is caused by a deletion of the short arm of chromosome 13 (13p), resulting in distinctive cat-like crying sounds in infants, developmental delays, and intellectual disabilities. Phelan-McDermid syndrome is caused by a deletion or mutation of the terminal end of the long arm of chromosome 13 (13q), leading to developmental delays, intellectual disability, absent or delayed speech, and autistic behaviors.
It's important to note that while some genetic disorders are associated with specific chromosomal abnormalities, many factors can contribute to the development and expression of these conditions, including environmental influences and interactions between multiple genes.
An oocyte, also known as an egg cell or female gamete, is a large specialized cell found in the ovary of female organisms. It contains half the number of chromosomes as a normal diploid cell, as it is the product of meiotic division. Oocytes are surrounded by follicle cells and are responsible for the production of female offspring upon fertilization with sperm. The term "oocyte" specifically refers to the immature egg cell before it reaches full maturity and is ready for fertilization, at which point it is referred to as an ovum or egg.
Hygromycin B is an antibiotic that is primarily used in research and agriculture. It is produced by the bacterium Streptomyces hygroscopicus and is active against both gram-positive and gram-negative bacteria, as well as some eukaryotic cells. In medicine, it is not commonly used due to its toxicity to mammalian cells.
In a laboratory setting, Hygromycin B is often used as a selection agent in molecular biology to ensure the growth of only those cells that have been genetically modified to express resistance to the antibiotic. This is typically achieved through the introduction of a gene that confers resistance to Hygromycin B.
In agriculture, it is used to control bacterial and fungal infections in plants. However, its use is restricted in some countries due to concerns about the development of antibiotic resistance and potential harm to non-target organisms.
Phosphoribosylglycinamide formyltransferase (PGTF) is an enzyme involved in the biosynthesis of purine nucleotides, which are essential components of DNA and RNA. The systematic medical definition of PGTF is:
"An enzyme that catalyzes the transfer of a formyl group from 10-formyltetrahydrofolate to the amino group of phosphoribosylglycinamide, forming N-formylphosphoribosylglycinamide and tetrahydrofolate as byproducts. This reaction is the fourth step in the de novo synthesis pathway of purine nucleotides."
PGTF's gene name is GART (Glycinamide Ribonucleotide Transformylase), and it is located on human chromosome 10q24.32-q25.1. Mutations in the GART gene can lead to a rare autosomal recessive disorder called Lesch-Nyhan syndrome, which is characterized by hyperuricemia, neurological symptoms, and self-mutilating behavior.
A mutation is a permanent change in the DNA sequence of an organism's genome. Mutations can occur spontaneously or be caused by environmental factors such as exposure to radiation, chemicals, or viruses. They may have various effects on the organism, ranging from benign to harmful, depending on where they occur and whether they alter the function of essential proteins. In some cases, mutations can increase an individual's susceptibility to certain diseases or disorders, while in others, they may confer a survival advantage. Mutations are the driving force behind evolution, as they introduce new genetic variability into populations, which can then be acted upon by natural selection.
Sister chromatid exchange (SCE) is a type of genetic recombination that takes place between two identical sister chromatids during the DNA repair process in meiosis or mitosis. It results in an exchange of genetic material between the two chromatids, creating a new combination of genes on each chromatid. This event is a normal part of cell division and helps to increase genetic variability within a population. However, an increased rate of SCEs can also be indicative of exposure to certain genotoxic agents or conditions that cause DNA damage.
A heterozygote is an individual who has inherited two different alleles (versions) of a particular gene, one from each parent. This means that the individual's genotype for that gene contains both a dominant and a recessive allele. The dominant allele will be expressed phenotypically (outwardly visible), while the recessive allele may or may not have any effect on the individual's observable traits, depending on the specific gene and its function. Heterozygotes are often represented as 'Aa', where 'A' is the dominant allele and 'a' is the recessive allele.
The synaptonemal complex is a protein structure that forms between two homologous chromosomes during meiosis, the type of cell division that leads to the production of gametes (sex cells). The synaptonemal complex consists of two lateral elements, which are associated with each of the homologous chromosomes, and a central element that runs parallel to the length of the complex and connects the two lateral elements.
The synaptonemal complex plays a crucial role in the process of genetic recombination, which occurs during meiosis. Genetic recombination is the exchange of genetic material between two homologous chromosomes that results in new combinations of genes on the chromosomes. This process helps to increase genetic diversity and is essential for the proper segregation of chromosomes during meiosis.
The synaptonemal complex also helps to ensure that the correct number of chromosomes are distributed to each gamete by holding the homologous chromosomes together until they can be properly aligned and separated during meiosis. Mutations in genes involved in the formation and maintenance of the synaptonemal complex can lead to fertility problems, developmental abnormalities, and other genetic disorders.
Chromosome breakage is a medical term that refers to the breaking or fragmentation of chromosomes, which are thread-like structures located in the nucleus of cells that carry genetic information. Normally, chromosomes are tightly coiled and consist of two strands called chromatids, joined together at a central point called the centromere.
Chromosome breakage can occur spontaneously or be caused by environmental factors such as radiation or chemicals, or inherited genetic disorders. When a chromosome breaks, it can result in various genetic abnormalities, depending on the location and severity of the break.
For instance, if the break occurs in a region containing important genes, it can lead to the loss or alteration of those genes, causing genetic diseases or birth defects. In some cases, the broken ends of the chromosome may rejoin incorrectly, leading to chromosomal rearrangements such as translocations, deletions, or inversions. These rearrangements can also result in genetic disorders or cancer.
Chromosome breakage is commonly observed in individuals with certain inherited genetic conditions, such as Bloom syndrome, Fanconi anemia, and ataxia-telangiectasia, which are characterized by an increased susceptibility to chromosome breakage due to defects in DNA repair mechanisms.
Polyploidy is a condition in which a cell or an organism has more than two sets of chromosomes, unlike the typical diploid state where there are only two sets (one from each parent). Polyploidy can occur through various mechanisms such as errors during cell division, fusion of egg and sperm cells that have an abnormal number of chromosomes, or through the reproduction process in plants.
Polyploidy is common in the plant kingdom, where it often leads to larger size, increased biomass, and sometimes hybrid vigor. However, in animals, polyploidy is less common and usually occurs in only certain types of cells or tissues, as most animals require a specific number of chromosomes for normal development and reproduction. In humans, polyploidy is typically not compatible with life and can lead to developmental abnormalities and miscarriage.
Monosomy is a type of chromosomal abnormality in which there is only one copy of a particular chromosome instead of the usual pair in a diploid cell. In monosomy, an individual has one less chromosome than the normal diploid number (46 chromosomes) due to the absence of one member of a chromosome pair. This condition arises from the loss of one chromosome in an egg or sperm during gamete formation or at conception.
Examples of monosomy include Turner syndrome, which is characterized by the presence of only one X chromosome (45,X), and Cri du Chat syndrome, which results from a deletion of a portion of the short arm of chromosome 5 (46,del(5)(p15.2)). Monosomy can lead to developmental abnormalities, physical defects, intellectual disabilities, and various health issues depending on the chromosome involved.
Chromosome banding is a technique used in cytogenetics to identify and describe the physical structure and organization of chromosomes. This method involves staining the chromosomes with specific dyes that bind differently to the DNA and proteins in various regions of the chromosome, resulting in a distinct pattern of light and dark bands when viewed under a microscope.
The most commonly used banding techniques are G-banding (Giemsa banding) and R-banding (reverse banding). In G-banding, the chromosomes are stained with Giemsa dye, which preferentially binds to the AT-rich regions, creating a characteristic banding pattern. The bands are numbered from the centromere (the constriction point where the chromatids join) outwards, with the darker bands (rich in A-T base pairs and histone proteins) labeled as "q" arms and the lighter bands (rich in G-C base pairs and arginine-rich proteins) labeled as "p" arms.
R-banding, on the other hand, uses a different staining procedure that results in a reversed banding pattern compared to G-banding. The darker R-bands correspond to the lighter G-bands, and vice versa. This technique is particularly useful for identifying and analyzing specific regions of chromosomes that may be difficult to visualize with G-banding alone.
Chromosome banding plays a crucial role in diagnosing genetic disorders, identifying chromosomal abnormalities, and studying the structure and function of chromosomes in both clinical and research settings.
Chromosomes in plants are thread-like structures that contain genetic material, DNA, and proteins. They are present in the nucleus of every cell and are inherited from the parent plants during sexual reproduction. Chromosomes come in pairs, with each pair consisting of one chromosome from each parent.
In plants, like in other organisms, chromosomes play a crucial role in inheritance, development, and reproduction. They carry genetic information that determines various traits and characteristics of the plant, such as its physical appearance, growth patterns, and resistance to diseases.
Plant chromosomes are typically much larger than those found in animals, making them easier to study under a microscope. The number of chromosomes varies among different plant species, ranging from as few as 2 in some ferns to over 1000 in certain varieties of wheat.
During cell division, the chromosomes replicate and then separate into two identical sets, ensuring that each new cell receives a complete set of genetic information. This process is critical for the growth and development of the plant, as well as for the production of viable seeds and offspring.
Pollen, in a medical context, refers to the fine powder-like substance produced by the male reproductive organ of seed plants. It contains microscopic grains known as pollen grains, which are transported by various means such as wind, water, or insects to the female reproductive organ of the same or another plant species for fertilization.
Pollen can cause allergic reactions in some individuals, particularly during the spring and summer months when plants release large amounts of pollen into the air. These allergies, also known as hay fever or seasonal allergic rhinitis, can result in symptoms such as sneezing, runny nose, congestion, itchy eyes, and coughing.
It is important to note that while all pollen has the potential to cause allergic reactions, certain types of plants, such as ragweed, grasses, and trees, are more likely to trigger symptoms in sensitive individuals.
In the context of medicine, spores are typically discussed in relation to certain types of infections and diseases caused by microorganisms such as bacteria or fungi. Spores are a dormant, resistant form of these microorganisms that can survive under harsh environmental conditions, such as extreme temperatures, lack of nutrients, and exposure to chemicals.
Spores can be highly resistant to heat, radiation, and disinfectants, making them difficult to eliminate from contaminated surfaces or medical equipment. When the conditions are favorable, spores can germinate and grow into mature microorganisms that can cause infection.
Some examples of medically relevant spores include those produced by Clostridioides difficile (C. diff), a bacterium that can cause severe diarrhea and colitis in hospitalized patients, and Aspergillus fumigatus, a fungus that can cause invasive pulmonary aspergillosis in immunocompromised individuals.
It's worth noting that spores are not unique to medical contexts and have broader relevance in fields such as botany, mycology, and biology.
Spermatozoa are the male reproductive cells, or gametes, that are produced in the testes. They are microscopic, flagellated (tail-equipped) cells that are highly specialized for fertilization. A spermatozoon consists of a head, neck, and tail. The head contains the genetic material within the nucleus, covered by a cap-like structure called the acrosome which contains enzymes to help the sperm penetrate the female's egg (ovum). The long, thin tail propels the sperm forward through fluid, such as semen, enabling its journey towards the egg for fertilization.
Anaphase is a stage in the cell division process called mitosis, where sister chromatids (the two copies of each chromosome formed during DNA replication) separate at the centromeres and move toward opposite poles of the cell. This separation is facilitated by the attachment of microtubules from the spindle apparatus to the kinetochores, protein structures located on the centromeres of each sister chromatid. Anaphase is followed by telophase, during which the nuclear membrane reforms around each set of separated chromosomes, and cytokinesis, the division of the cytoplasm to form two separate daughter cells.
'Zea mays' is the biological name for corn or maize, which is not typically considered a medical term. However, corn or maize can have medical relevance in certain contexts. For example, cornstarch is sometimes used as a diluent for medications and is also a component of some skin products. Corn oil may be found in topical ointments and creams. In addition, some people may have allergic reactions to corn or corn-derived products. But generally speaking, 'Zea mays' itself does not have a specific medical definition.
"Drosophila" is a genus of small flies, also known as fruit flies. The most common species used in scientific research is "Drosophila melanogaster," which has been a valuable model organism for many areas of biological and medical research, including genetics, developmental biology, neurobiology, and aging.
The use of Drosophila as a model organism has led to numerous important discoveries in genetics and molecular biology, such as the identification of genes that are associated with human diseases like cancer, Parkinson's disease, and obesity. The short reproductive cycle, large number of offspring, and ease of genetic manipulation make Drosophila a powerful tool for studying complex biological processes.
"Saccharomyces cerevisiae" is not typically considered a medical term, but it is a scientific name used in the field of microbiology. It refers to a species of yeast that is commonly used in various industrial processes, such as baking and brewing. It's also widely used in scientific research due to its genetic tractability and eukaryotic cellular organization.
However, it does have some relevance to medical fields like medicine and nutrition. For example, certain strains of S. cerevisiae are used as probiotics, which can provide health benefits when consumed. They may help support gut health, enhance the immune system, and even assist in the digestion of certain nutrients.
In summary, "Saccharomyces cerevisiae" is a species of yeast with various industrial and potential medical applications.
Pentasomy X
Trisomy X
Tetrasomy X
Polysomy
Homologous chromosome
Aneuploidy
Sterility (physiology)
XXXY syndrome
Mosaic (genetics)
MTRR (gene)
Blastomere
Chromosomal deletion syndrome
Male infertility
Pseudolinkage
XYY syndrome
Nondisjunction
Caenorhabditis elegans
Turner syndrome
Tetrasomy 18p
Patau syndrome
Klinefelter syndrome
Glossary of genetics (M-Z)
Autosome
Birdwing
Small supernumerary marker chromosome
List of MeSH codes (C23)
Nullisomic
Somatic mutation and recombination tests
Chromosome abnormality
Somatic evolution in cancer
Leukemia in Down syndrome: a review
Pentasomy X - Wikipedia
MeSH Browser
Sterility (physiology) - Wikipedia
Pallister-Killian mosaic syndrome: MedlinePlus Genetics
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Chromosomal Abnormalities: Trisomy 21 (Down Syndrome) | NCBDDD | CDC
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Chromosomes14
- Chromosomes are thread-like structures located inside the nucleus of cells that contain genetic information. (proprofs.com)
- Nondisjunction in meiosis can lead to an abnormal number of chromosomes in the resulting cells, which is the cause of Down syndrome, Turner's syndrome, and Klinefelter's syndrome. (proprofs.com)
- Failure to control the timing and frequency of recombination events results in mis-segregation, or non-disjunction, of chromosomes that results in embryos that are either not viable (resulting in miscarriage) or in offspring with genetic disorders such as trisomy 21, or Down syndrome. (cornell.edu)
- During prophase I, crossing over introduces genetic variation by swapping pieces of homologous chromosomes. (styleslicker.com)
- Genetic Disorders refer to any abnormality in the individual gene(s) or the chromosomes which are caused due to the change in the sequence of the DNA or gain or loss of gene(s) or chromosomes. (solarpoultry.com)
- Chromosomes are tiny units made up of DNA that contain the entire genetic makeup of an individual. (livlong.com)
- Klinefelter syndrome is a genetic condition that affects males by causing them to be born with one or more extra X chromosomes. (ro.co)
- It's during this step that each half of the cell has an exact copy of the genetic information, thereby ensuring that each new cell has a complete set of chromosomes. (biologyideas.com)
- Both in mitosis and meiosis, anaphase ensures each newly formed cell has a complete and accurate set of chromosomes, thus safeguarding the genetic integrity of an organism. (biologyideas.com)
- At its most basic, the karyogram may reveal genetic abnormalities in which an individual has too many or too few chromosomes per cell. (opentextbc.ca)
- They are caused by nondisjunction , which occurs when pairs of homologous chromosomes or sister chromatids fail to separate during meiosis. (opentextbc.ca)
- These chromosomes play a pivotal role in various aspects of human development, including metabolic pathways, cellular homeostasis , and genetic disorders. (biologyonline.com)
- Chromosome trisomy is usually caused by the nondisjunction of homologous chromosomes during gamete formation, especially from the balanced translocation carriers in the parents. (biomedcentral.com)
- Chromosomes are the units of genetic information that exist within every cell of the body. (findmeacure.com)
Chromosomal4
- Genetic variation results from the crossing over and exchange of chromosomal parts that occur during meiosis II. (easynotecards.com)
- Mostly, the causes are autosomal and sex chromosomal nondisjunction . (wikidoc.org)
- The proximal lesion because of nondisjunction (error in chromosomal region 19q9 is a genetic diagnosis is a. (lowerbricktown.com)
- By observing a karyogram, geneticists can actually visualize the chromosomal composition of an individual to confirm or predict genetic abnormalities in offspring even before birth. (opentextbc.ca)
Syndrome14
- Down syndrome, also known as trisomy 21, is a genetic condition characterised by the presence of a partial or full additional copy of chromosome 21 in an individual. (livlong.com)
- The presence of extra genetic material in individuals with Down syndrome leads to the display of symptoms such as an upward eye slant, a small stature, and one deep crease on the palm. (livlong.com)
- Experts understand that, at a genetic level, the syndrome is caused by something known as nondisjunction. (ro.co)
- Trisomy 21 or Down syndrome (DS) is the most common genetic cause of mental retardation. (manipal.edu)
- These aberrations can lead to various genetic disorders, such as Down syndrome. (biologyideas.com)
- Another relatively rare genetic accident which can cause Down syndrome is called translocation. (findmeacure.com)
- Edward Syndrome, clinically known as Trisomy 18, is a relatively uncommon but serious genetic disorder that profoundly impacts human life (Hasegawa, Matsuoka, & Shimizu, 2016). (anthroholic.com)
- The following comprehensive exploration aims to shed light on the intricacies of Edward Syndrome, including its genetic basis, associated physical features, diagnostic procedures, management strategies, and the profound impact it has on the lives of affected individuals and their families. (anthroholic.com)
- Edward Syndrome occurs as a consequence of an error in cell division known as nondisjunction, leading to the formation of an extra chromosome 18 (Jones, Hassold, & Harvey, 2012). (anthroholic.com)
- The diagnosis of Edward Syndrome is generally made prenatally through screening and diagnostic tests, though it may also be diagnosed postnatally based on physical characteristics and confirmed by genetic testing. (anthroholic.com)
- If Edward Syndrome is suspected based on physical characteristics after birth, genetic testing, such as karyotyping or FISH, can confirm the diagnosis (Cereda & Carey, 2012). (anthroholic.com)
- Down syndrome is the best-known example of a prenatal genetic disorder. (medscape.com)
- In 95% of cases, Down syndrome is caused by trisomy 21, in which the extra chromosome 21 in the egg or sperm cell results from the nondisjunction in the meiotic stage. (medscape.com)
- This is important in genetic counseling because when the mother or father has a t(14;21) translocation, the chance of having a child with Down syndrome is 1 in 10 if in the mother or 1 in 20 if in the father. (medscape.com)
Disorders10
- Which of the following disorders does NOT result from nondisjunction in meiosis? (proprofs.com)
- There are a lot of misconceptions about genetic disorders and inheritance. (texas.gov)
- Genetic Disorders. (solarpoultry.com)
- Prenatal genetic counseling is provided for all prospective parents, ideally before conception, to assess risk factors for congenital disorders. (msdmanuals.com)
- Preimplantation Genetic Testing (PGT) All procedures used to diagnose genetic disorders, except ultrasonography, are invasive and involve slight fetal risk. (msdmanuals.com)
- Aberrations in autosomal genes can give rise to a wide range of genetic disorders. (biologyonline.com)
- Studying autosomal genetic disorders provides valuable insights into disease mechanisms and paves the way for targeted therapies and genetic counseling for the human creed. (biologyonline.com)
- This is why autosomes form the backbone of human genetics as they hold the key to our intricate biological processes and susceptibility to genetic disorders. (biologyonline.com)
- Prenatal genetic disorders are characterized by changes in the genetic material, which may or may not have been inherited from the parents. (medscape.com)
- Ovotesticular disorder of sexual development, which was previously termed "intersex," describes disorders in which there is a discrepancy between a person's phenotype, genetic material, and gonads. (medscape.com)
Aneuploidy4
- Nondisjunction or failure in bivalent formation impairs reductional segregation, incessantly inflicting aneuploidy in gametes. (styleslicker.com)
- Mosaic results after preimplantation genetic testing for aneuploidy may be accompanied by changes in global gene expression. (ivi-rmainnovation.com)
- Preimplantation genetic testing for aneuploidy is not related to adverse obstetric and neonatal outcomes in singleton pregnancies. (ivi-rmainnovation.com)
- Update on preimplantation genetic testing for aneuploidy and outcomes of embryos with mosaic results. (ivi-rmainnovation.com)
Meiosis6
- Sickle cell disease is not caused by nondisjunction in meiosis. (proprofs.com)
- The process of meiosis is additional characterised by synapsis formation, the meeting of synaptonemal complicated and chiasma formation, bringing about genetic range during gametogenesis. (styleslicker.com)
- These parental cells must go through a very specific kind of division called meiosis where new cells have exactly half the genetic material. (texas.gov)
- State two ways in which meiosis gives rise to genetic variation. (collepals.com)
- This genetic condition almost always results from nondisjunction during meiosis. (icd.codes)
- Nondisjunction can occur during either meiosis I or II, with different results ( Figure 7.8 ). (opentextbc.ca)
Gamete2
- Pentasomy X is not inherited, but rather occurs via nondisjunction, a random event in gamete development. (wikipedia.org)
- They include slight variations in their genetic information, causing each gamete to have a singular genetic makeup. (styleslicker.com)
Gene4
- The positive result in the in vitro mouse lymphoma assay will not lead to classification with respect to gene mutation as the in vivo equivalent showed no evidence of genetic mutation. (europa.eu)
- It is a genetic disorder that results from a mutation in the hemoglobin gene, causing red blood cells to become sickle-shaped. (proprofs.com)
- Assuming that plant height is controlled by a single gene, use genetic symbols to explain the F1 phenotype, and indicate the relationship between the two alleles (e.g., dominant, or recessive, or Éetc. (collepals.com)
- Thus, the fact that, a gene can function irrespective of its environment formed the basis for genetic engineering. (smartindia.net.in)
Variation3
- This randomness, known as unbiased assortment, is the bodily basis for the technology of the second form of genetic variation in offspring. (styleslicker.com)
- Of the different sources of genetic variability, which one produces the variation in the combinations of alleles on a single chromosome? (easynotecards.com)
- Copy number variations (CNVs) have been linked to dozens of human diseases, but can they also represent the genetic variation that was so essential to our evolution? (nature.com)
Occurs1
- Nondisjunction usually occurs as the result of a weakened mitotic checkpoint , as these checkpoints tend to arrest or delay cell division until all components of the cell are ready to enter the next phase. (wikidoc.org)
Disorder3
- The extra genetic material from the isochromosome disrupts the normal course of development, causing the characteristic features of this disorder. (medlineplus.gov)
- Many genetic conditions are also inherited this way, such as: Cystic Fibrosis, Sickle Cell Anemia and Tay-Sachs Disorder. (texas.gov)
- This form of genetic disorder is called a mosaic. (findmeacure.com)
Mosaicism1
- Together, these data demonstrate that human brain cells (both neurons and non-neuronal cells) can be aneuploid and that the resulting genetic mosaicism is a normal feature of the human CNS. (jneurosci.org)
Mutation1
- Environmentally produced phenotypes that mimic conditions that may be caused by genetic mutation are called phenocopies. (easynotecards.com)
Variability4
- It has been subject of many evolutionary studies within the group, due to its considerable ability to successfully occupy a wide range of environments and also because of its great genetic variability expressed by different markers. (scielo.br)
- Our results indicate that the D. willistoni 17A2 strain is a candidate for hypermutability, which presents considerable cryptic genetic variability. (scielo.br)
- Of the different sources of genetic variability, which one could be defined as permanent, transmissible changes to the DNA coding sequence often caused by outside environmental factors? (easynotecards.com)
- Molecular markers for the analysis of genetic variability and for genetic profiling. (unipv.it)
Humans1
- The similarity of the eyes of humans and cephalopods is an example of A. The transmission of genetic information via bacterial transfection. (grouperfishingsecrets.com)
Prenatal1
- Prenatal Genetic Testing of Parents Genetic testing is part of routine prenatal care and is ideally done before conception. (msdmanuals.com)
Sperm1
- In maize the nondisjunction takes place at the second pollen mitosis, followed by preferential fertilization of the egg by the Bcarrying sperm, and likewise constitutes a selfish drive mechanism that causes the Bs to spread in natural populations. (ristudypost.com)
Makeup2
- Actual genetic makeup. (easynotecards.com)
- Anaphase's influence extends to the organism's genetic makeup, emphasizing its far-reaching impact beyond mere cell division. (biologyideas.com)
Mitotic1
- In addition, there are systems of mitotic drive in some species (especially Gramineae) based on nondisjunction in gametophytes. (ristudypost.com)
Preimplantation3
- Improved clinical utility of preimplantation genetic testing through the integration of ploidy and common pathogenic microdeletions analyses. (ivi-rmainnovation.com)
- Antimüllerian hormone (AMH) and age as predictors of preimplantation genetic testing for aneuploidies (PGT-A) cycle outcomes and blastocyst quality on day 5 in women undergoing in vitro fertilization (IVF). (ivi-rmainnovation.com)
- Preimplantation genetic diagnosis might effectively assist those women with an adverse pregnancy history in their next pregnancy. (biomedcentral.com)
Metabolic pathways1
- The genetic analysis of metabolic pathways. (unipv.it)
Explain1
- 7.Explain briefly Genetic Engineering? (smartindia.net.in)
Karyotype2
- Clinical diagnosis should be confirmed by genetic testing (typically, karyotype from infant's blood or tissue). (cdc.gov)
- Finally, the karyotype can pinpoint translocations, which occur when a segment of genetic material breaks from one chromosome and reattaches to another chromosome or to a different part of the same chromosome. (opentextbc.ca)
Nucleus1
- c) First mitosis of the pollen grain, showing a single B (arrowed) undergoing directed nondisjunction to the generative nucleus. (ristudypost.com)
Abnormality1
- Some risk of genetic abnormality exists in all pregnancies. (msdmanuals.com)
Results2
Pairs1
- Consisting of 22 pairs, autosomes carry a wealth of genetic information that governs numerous biological processes. (biologyonline.com)
Traits1
- A plasmid sometimes can leave from one bacterial cell and enter another, through, conjugation and thereby transfer genetic traits to the recepient cell. (smartindia.net.in)
Material3
- Inversions: A portion of the chromosome has broken off, turned upside down, and reattached, therefore the genetic material is inverted. (solarpoultry.com)
- It's during this stage that copies of genetic material get distributed evenly and precisely. (biologyideas.com)
- The course will also deal with the structural and functional features of genetic material, how genetic information is stored, coded and expressed in prokaryotes and eukaryotes. (unipv.it)
Trait3
- Genetic engineers find ways to modify the DNA of organisms to create a desired trait or protein, such as making a crop resistant to a certain herbicide or making bacteria that create human insulin. (teachengineering.org)
- What is a dominant genetic trait? (fountainessays.com)
- Alleles may code for alternative expressions of a genetic trait. (easynotecards.com)
Embryos1
- PGT) is used to identify genetic defects in embryos created through in vitro fertilization before they are implanted. (msdmanuals.com)
Epigenetic1
- Sex differences at the genetic/epigenetic level in early development. (ubc.ca)
Result2
- As a result, all genetic problems are due exclusively to nuclear genes. (easynotecards.com)
- However, genetic changes in the embryo often result in clinical phenotypic changes. (biomedcentral.com)
Vitro2
Conjugation1
- Genetic mapping in bacteria and phages: conjugation, transduction and transformation. (unipv.it)
Genes1
- Genetic engineering deals with the manipulation of genes according to human will. (smartindia.net.in)
Parents2
- KS is a genetic condition but it is not inherited from your parents. (clinicforhim.com)
- The risk of nondisjunction increases with the age of the parents. (opentextbc.ca)
Diseases1
- Genetic diseases in human beings can be detected by this technique. (smartindia.net.in)
Explanation1
- c) What is the genetic explanation for the absence of plants with red and white in the flowers F1 generation? (atikaschool.org)
Cell Division2
- Anaphase, a fundamental step in the process of cell division, plays a crucial role in ensuring accurate genetic information transfer. (biologyideas.com)
- Residing in this sequential placement of the cell cycle, its role has a significant impact on the accuracy of cell division and genetic expression. (biologyideas.com)
Human1
- They hold a vast repository of genetic information that governs various aspects of human biology. (biologyonline.com)
Cellular1
- Thus, anaphase and its precise execution are crucial for maintaining genetic stability and cellular health. (biologyideas.com)
Vast1
- Anaphase holds vast importance in the division of cells and ensuring genetic continuity. (biologyideas.com)