| YAC | Yeast Artificial Chromosome |
|---|---|
| HC21 | human chromosome 21 |
| WCP | whole chromosome painting |
| polytene chromosome | <cell biology> Giant chromosomes produced by the successive replication of homologous pairs of chromosomes, joined together (synapsed) without chromosome separation or nuclear division. They thus consist of many up to 1000) identical chromosomes (strictly chromatids) running parallel and in strict register. The chromosomes remain visible during interphase and are found in some ciliates, ovule cells in angiosperms and in larval Dipteran tissue. The best known polytene chromosomes are those of the salivary gland of the larvae of Drosophila melanogaster which appear as a series of dense bands interspersed by light interbands, in a pattern characteristic for each chromosome. The bands, of which there are about 5,000 in Drosophila melanogaster, contain most of the DNA (ca 95%) of the chromosomes and each band roughly represents one gene. The banding pattern of polytene chromosomes provides a visible map to compare with the linkage map determined by genetic studies. Some segments of polytene chromosome show chromosome puffs, areas of high transcription. (18 Nov 1997) |
|---|---|
| harlequin chromosome | <cell biology> A chromosome which, when stained, produces a banded pattern of alternating light and dark segments (also called a harlequin pattern). It is made by treating a cell with 5'-bromodeoxyuridine, the chemical incorporates into the cells DNA and when stained is lighter than the DNA around it. (09 Oct 1997) |
| heterotypical chromosome | <genetics> One or more chromosomes that can be distinguished from autosomes by their morphology and behaviour. Synonym: accessory chromosome, heterochromosome, sex chromosome. (18 Nov 1997) |
| X chromosome | <genetics> A sex chromosome. In mammals paired in females (XX), in amphibia paired in males. (11 May 1997) |
| homologous chromosome | <genetics> A pair of chromosomes containing the same linear gene sequences, each derived from one parent. The chromosomes tend to pair or synapse during mitosis. (14 Oct 1997) |
| sex chromosome | <genetics> Chromosome that determines the sex of an animal. In humans, where the two sex chromosomes (X and Y) are dissimilar, the female has two X chromosomes and the male is heterogametic (XY). <zoology> In birds, the opposite is the case, the male being XX and the female XY, in many organisms, there is only one sex chromosome and one sex is XX, the other X0. A portion of the X and Y chromosomes is similar and is known as the pseudoautosomal region. (14 Oct 1997) |
| sex chromosome imbalance | Any abnormal pattern of sex chromosomes; e.g., XXY in men with seminiferous tubule dysgenesis, XO in women with Turner's syndrome; rarer patterns of imbalance are XXX, XXXY, and XYY. See: isochromosome. (05 Mar 2000) |
| submetacentric chromosome | A chromosome with the centromere so placed that it divides the chromosome into two arms of strikingly unequal length. (05 Mar 2000) |
| nucleolar chromosome | A chromosome regularly associated with a nucleolus. (05 Mar 2000) |
| derivative chromosome | An anomalous chromosome generated by translocation. Synonym: translocation chromosome. (05 Mar 2000) |
| dicentric chromosome | <cell biology> A chromosome with two centromeres instead of the normal one. Such an oddity can form if chromosomes break and then the fragments re-fuse with one another in a different combination than before they broke. (09 Oct 1997) |
| quinacrine chromosome banding stain | q-banding stain |
| odd chromosome | A chromosome existing without its normal homologous chromosome; at the reduction division of gametogenesis an accessory chromosome is likely to be included in one daughter cell and not in the other, but may be lost completely by lagging behind on the equatorial plate. Synonym: monosome, odd chromosome, unpaired allosome, unpaired chromosome. (05 Mar 2000) |
| telocentric chromosome | <genetics> Chromosome with the centromere located at one end. (18 Nov 1997) |
| translocation chromosome | An anomalous chromosome generated by translocation. Synonym: translocation chromosome. (05 Mar 2000) |