Chromosome inversion, pericentric: A basic type of chromosome rearrangement in which a segment that includes the centromere (and is therefore pericentric) is snipped out of a chromosome, inverted, and inserted back into the chromosome. The feature that makes it pericentric is that the breaks are on both sides of the centromere.
- Chromosome map
Chromosome map: The chart of the linear array of genes on a chromosome. A chromosome map can also refer to the visual appearance of a chromosome when stained and examined under a microscope. Particularly important are visually distinct regions, called light and dark bands, which give each of the chromosomes a unique appearance. This feature […]
- Chromosome, acentric
Chromosome, acentric: A fragment of a chromosome that lacks a centromere, so that the chromosome is lost when the cell divides.
- Chromosome, acrocentric
Chromosome, acrocentric: A chromosome that has its centromere located near one end of the chromosome. Humans have five pairs of acrocentric chromosomes. Down syndrome is due to an extra acrocentric chromosome (chromosome 21).
- Chromosome, dicentric
Chromosome, dicentric: A chromosome that is abnormal in that it has two centromeres rather than one. Because the centromere is essential for chromosome division, a dicentric chromosome is pulled in opposite directions when the cell divides. This causes the chromosome to form a bridge and then break and be unstable.
- Chromosome, marker
Chromosome, marker: An abnormal chromosome that is distinctive in appearance but not fully identified. A marker chromosome is not necessarily a marker for a specific disease or abnormality, but it can be distinguished under the microscope from all the normal human chromosomes. For example, the fragile X (FRAXA) chromosome was once called the marker X.