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Genomic instability is a common feature of cancer; therefore understanding structural and chromosomal abnormalities can give insight into the progression of disease. The Cancer Chromosome Aberration Project (cCAP) is a CGAP supported initiative used for defining chromosome structure and to characterize rearrangements that are associated with ...
A chromosomal abnormality, chromosomal anomaly, chromosomal aberration, chromosomal mutation, or chromosomal disorder is a missing, extra, or irregular portion of chromosomal DNA. [ 1 ] [ 2 ] These can occur in the form of numerical abnormalities, where there is an atypical number of chromosomes, or as structural abnormalities, where one or ...
The clastogenic or aneugenic effects from the genotoxic damage will cause an increase in frequency of structural or numerical aberrations of the genetic material. [6] This is similar to the micronucleus test and chromosome aberration assay, which detect structural and numerical chromosomal aberrations in mammalian cells. [1]
Chromosomes display a banded pattern when treated with some stains. Bands are alternating light and dark stripes that appear along the lengths of chromosomes. Unique banding patterns are used to identify chromosomes and to diagnose chromosomal aberrations, including chromosome breakage, loss, duplication, translocation or inverted segments.
A chromosomal instability assay should measure not only whole chromosome change rates, but also the partial chromosomal changes such as deletions, insertions, inversion and amplifications to also take into account segmental aneuploidies. [5] This provides a more accurate determination of the presence of chromosome instability.
Comparative genomic hybridization (CGH), derived from FISH, is used to compare variations in copy number between a biological sample and a reference. CGH was originally developed to observe chromosomal aberrations in tumour cells. This method uses two genomes, a sample and a control, which are labeled fluorescently to distinguish them. [5]
Next, the cells are dropped onto a microscope slide so that the nucleus, which holds all of the genetic material together, breaks apart and releases the chromosomes onto the slide. Then, under a microscope, the scientist locates the specific band of interest, and, using a very fine needle, tears that band away from the rest of the chromosome.
It may not always be known how a clastogen causes chromosomal damage. Radiation was the earliest known clastogen that caused direct DNA damage, following the classic breaks theory. [ 6 ] DNA is frequently damaged and there are many DNA repair pathways that combat this, but repair does not always work perfectly resulting in mistakes (called a ...