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Breakage-fusion-bridge Cycle
Breakage-fusion-bridge (BFB) cycle (also breakage-rejoining-bridge cycle) is a mechanism of chromosomal instability, discovered by Barbara McClintock in the late 1930s. Mechanism The BFB cycle begins when the end region of a chromosome, called its telomere, breaks off. When that chromosome subsequently replicates it forms two sister chromatids which both lack a telomere. Since telomeres appear at the end of chromatids, and function to prevent their ends from fusing with other chromatids, the lack of a telomere on these two sister chromatids causes them to fuse with one another. During anaphase the sister chromatids will form a bridge where the centromere in one of the sister chromatids will be pulled in one direction of the dividing cell, while the centromere of the other will be pulled in the opposite direction. Being pulled in opposite directions will cause the two sister chromatids to break apart from each other, but not necessarily at the site that they fused. This results in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Abnormalities In Peripheral Blood Erythrocytes Of Penguins Pygoscelis Papua 3
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Nuclear may refer to: Physics Relating to the nucleus of the atom: *Nuclear engineering *Nuclear physics *Nuclear power *Nuclear reactor *Nuclear weapon *Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics *Nuclear space *Nuclear operator *Nuclear congruence *Nuclear C*-algebra Biology Relating to the nucleus of the cell: * Nuclear DNA Society *Nuclear family, a family consisting of a pair of adults and their children Music * "Nuclear" (band), group music. * "Nuclear" (Ryan Adams song), 2002 *"Nuclear", a song by Mike Oldfield from his ''Man on the Rocks'' album * ''Nu.Clear'' (EP) by South Korean girl group CLC See also *Nucleus (other) *Nucleolus *Nucleation *Nucleic acid *Nucular ''Nucular'' is a common, proscribed pronunciation of the word "nuclear". It is a rough phonetic spelling of . The ''Oxford English Dictionary''s entry dates the word's first published appearance to 1943. Dictionary notes This is one of two con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome Abnormality
A chromosomal abnormality, chromosomal anomaly, chromosomal aberration, chromosomal mutation, or chromosomal disorder, is a missing, extra, or irregular portion of chromosomal DNA. These can occur in the form of numerical abnormalities, where there is an atypical number of chromosomes, or as structural abnormalities, where one or more individual chromosomes are altered. Chromosome mutation was formerly used in a strict sense to mean a change in a chromosomal segment, involving more than one gene. Chromosome anomalies usually occur when there is an error in cell division following meiosis or mitosis. Chromosome abnormalities may be detected or confirmed by comparing an individual's karyotype, or full set of chromosomes, to a typical karyotype for the species via genetic testing. Numerical abnormality An abnormal number of chromosomes is called aneuploidy, and occurs when an individual is either missing a chromosome from a pair (resulting in monosomy) or has more than two chromosome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome Instability Syndrome
Chromosome instability syndromes are a group of inherited conditions associated with chromosomal instability and breakage. They often lead to an increased tendency to develop certain types of malignancies. The following chromosome instability syndromes are known: * Ataxia telangiectasia * Ataxia telangiectasia-like disorder * Bloom syndrome * Fanconi anaemia * Nijmegen breakage syndrome Neurodegenerative diseases Chromosome instability syndromes include several inherited neurodegenerative diseases that are due to mutations in genes that encode enzymes necessary for DNA repair. Epigenetic alterations often occur in association with the DNA repair defect, and such alterations likely have a role in the etiology of the disease. Chromosome instability syndromes due to impaired DNA repair and with features of neurodegeneration and epigenetic alteration were summarized by Bernstein and Bernstein. These syndromes include Aicardi-Goutieres syndrome, amyotrophic lateral sclerosis, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copy Number Analysis
Copy number analysis is the process of analyzing data produced by a test for DNA copy number variation in an organism's sample. One application of such analysis is the detection of chromosomal copy number variation that may cause or may increase risks of various critical disorders. Copy number variation can be detected with various types of tests such as fluorescent in situ hybridization, comparative genomic hybridization and with high-resolution array-based tests based on array comparative genomic hybridization (or aCGH), SNP array technologies and high resolution microarrays that include copy number probes as well an SNPs. Array-based methods have been accepted as the most efficient in terms of their resolution and high-throughput nature and the highest coverage (choose an array with over 2 million probes) and they are also referred to as virtual karyotype. Data analysis for an array-based DNA copy number test can be very challenging though due to very high volume of data that c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Sequencing
DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. The advent of rapid DNA sequencing methods has greatly accelerated biological and medical research and discovery. Knowledge of DNA sequences has become indispensable for basic biological research, DNA Genographic Projects and in numerous applied fields such as medical diagnosis, biotechnology, forensic biology, virology and biological systematics. Comparing healthy and mutated DNA sequences can diagnose different diseases including various cancers, characterize antibody repertoire, and can be used to guide patient treatment. Having a quick way to sequence DNA allows for faster and more individualized medical care to be administered, and for more organisms to be identified and cataloged. The rapid speed of sequencing attained with modern D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Microarray
A DNA microarray (also commonly known as DNA chip or biochip) is a collection of microscopic DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome. Each DNA spot contains picomoles (10−12 moles) of a specific DNA sequence, known as '' probes'' (or ''reporters'' or '' oligos''). These can be a short section of a gene or other DNA element that are used to hybridize a cDNA or cRNA (also called anti-sense RNA) sample (called ''target'') under high-stringency conditions. Probe-target hybridization is usually detected and quantified by detection of fluorophore-, silver-, or chemiluminescence-labeled targets to determine relative abundance of nucleic acid sequences in the target. The original nucleic acid arrays were macro arrays approximately 9 cm × 12 cm and the first computerized image based analysis was published in 1981. It was inv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromothripsis
Chromothripsis is a mutational process by which up to thousands of clustered chromosomal rearrangements occur in a single event in localised and confined genomic regions in one or a few chromosomes, and is known to be involved in both cancer and congenital diseases. It occurs through one massive genomic rearrangement during a single catastrophic event in the cell's history. It is believed that for the cell to be able to withstand such a destructive event, the occurrence of such an event must be the upper limit of what a cell can tolerate and survive. The chromothripsis phenomenon opposes the conventional theory that cancer is the gradual acquisition of genomic rearrangements and somatic mutations over time. The simplest model as to how these rearrangements occur is through the simultaneous fragmentation of distinct chromosomal regions (breakpoints show a non-random distribution) and then subsequent imperfect reassembly by DNA repair, DNA repair pathways or aberrant DNA replication ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlas Of Genetics And Cytogenetics In Oncology And Haematology
The Atlas of Genetics and Cytogenetics in Oncology and Haematology, created in 1997 by Jean-Loup Huret (with bioinformatics by Philippe Dessen) is a collection of resources on genes, chromosomes anomalies, leukemias, solid tumours, and cancer-prone diseases. The project is accessible through Internet and is made of encyclopedic-style files, as well as traditional overviews, links towards websites and databases devoted to cancer and/or genetics, case reports in haematology. It also encompasses teaching items in various languages. Starting first from cytogenetics in the nineteens, the Atlas now combines different types of knowledge in a single web site: genes and their function, cell biology (ex: Apoptosis), pathological data, diseases and their clinical implications, cytogenetics, but also medical genetics, with hereditary disorders associated with an increased risk of cancer. This gives a wider and more global view of cancer genetics, while these data are usually dispersed. It inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosomal Translocation
In genetics, chromosome translocation is a phenomenon that results in unusual rearrangement of chromosomes. This includes balanced and unbalanced translocation, with two main types: reciprocal-, and Robertsonian translocation. Reciprocal translocation is a chromosome abnormality caused by exchange of parts between non-homologous chromosomes. Two detached fragments of two different chromosomes are switched. Robertsonian translocation occurs when two non-homologous chromosomes get attached, meaning that given two healthy pairs of chromosomes, one of each pair "sticks" and blends together homogeneously. A gene fusion may be created when the translocation joins two otherwise-separated genes. It is detected on cytogenetics or a karyotype of affected cells. Translocations can be balanced (in an even exchange of material with no genetic information extra or missing, and ideally full functionality) or unbalanced (where the exchange of chromosome material is unequal resulting in extra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome Instability
Chromosomal instability (CIN) is a type of genomic instability in which chromosomes are unstable, such that either whole chromosomes or parts of chromosomes are duplicated or deleted. More specifically, CIN refers to the increase in rate of addition or loss of entire chromosomes or sections of them. The unequal distribution of DNA to daughter cells upon mitosis results in a failure to maintain euploidy (the correct number of chromosomes) leading to aneuploidy (incorrect number of chromosomes). In other words, the daughter cells do not have the same number of chromosomes as the cell they originated from. Chromosomal instability is the most common form of genetic instability and cause of aneuploidy. These changes have been studied in solid tumors (a tumor that usually doesn't contain liquid, pus, or air, compared to liquid tumor), which may or may not be cancerous. CIN is a common occurrence in solid and haematological cancers, especially colorectal cancer. Although many tumours sho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centromere
The centromere links a pair of sister chromatids together during cell division. This constricted region of chromosome connects the sister chromatids, creating a short arm (p) and a long arm (q) on the chromatids. During mitosis, spindle fibers attach to the centromere via the kinetochore. The physical role of the centromere is to act as the site of assembly of the kinetochores – a highly complex multiprotein structure that is responsible for the actual events of chromosome segregation – i.e. binding microtubules and signaling to the cell cycle machinery when all chromosomes have adopted correct attachments to the spindle, so that it is safe for cell division to proceed to completion and for cells to enter anaphase. There are, broadly speaking, two types of centromeres. "Point centromeres" bind to specific proteins that recognize particular DNA sequences with high efficiency. Any piece of DNA with the point centromere DNA sequence on it will typically form a centromere if pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anaphase
Anaphase () is the stage of mitosis after the process of metaphase, when replicated chromosomes are split and the newly-copied chromosomes (daughter chromatids) are moved to opposite poles of the cell. Chromosomes also reach their overall maximum condensation in late anaphase, to help chromosome segregation and the re-formation of the nucleus. Anaphase starts when the anaphase promoting complex marks an inhibitory chaperone called securin for destruction by ubiquinylating it. Securin is a protein which inhibits a protease known as separase. The destruction of securin unleashes separase which then breaks down cohesin, a protein responsible for holding sister chromatids together. At this point, three subclasses of microtubule unique to mitosis are involved in creating the forces necessary to separate the chromatids: kinetochore microtubules, interpolar microtubules, and astral microtubules. The centromeres are split, and the sister chromatids are pulled toward the poles by ki ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
