Each chromosome consists of a DNA double helix bearing a linear sequence of genes, coiled and recoiled around aggregated proteins (histones). Their number varies from species to species: humans have 22 pairs plus the two sex chromosomes (two X chromosomes in females, one X and one Y in males). During cell division, each DNA strand is duplicated, and the chromosomes condense to become visible as distinct pairs of chromatids joined at the centromere. Bacteria and viruses lack a nucleus and have a single chromosome without histones
- Ring chromosomes, chromatid exchanges and polyploidies were also observed at some treatments.
- The sizes of the two centromeres from the homologous chromosomes are different.
- The sex chromosomes are placed to the right of the smallest autosomal chromosomes.
late 19th century: coined in German from Greek khrōma 'color' + sōma 'body'.
- More example sentences
- The number of ovulated oocytes per female and the chromosomal constitution of these in vivo matured oocytes were analysed.
- The centromere is responsible for two key chromosomal functions in mitosis and meiosis.
- Numerical and structural chromosomal abnormalities within each metaphase were recorded.
Definition of chromosome in:
- The British & World English dictionary