DNA and genomes
Chromosomes and cell division
- The chromosome consists of a single chromatid and is decondensed (long and string-like).
- The DNA is copied. The chromosome now consists of two sister chromatids, which are connected by proteins called cohesins.
- The chromosome condenses. It is still made up of two sister chromatids, but they are now short and compact rather than long and stringy. They are most tightly connected at the centromere region, which is the inward-pinching "waist" of the chromosome.
- The chromatids are pulled apart. Each is now considered its own chromosome.