GENETICS Terms Chromosome

 

- Info:

- Chromosome contains single DNA molecule packaged by various proteins into a compact domain.

Chromosome is like ziped DNA.

- Stretched out DNA would form a very thin thread about 2 m long.

This DNA has to be packaged into the chromosome within a nucleus that is much smaller than a printed dot.

At the point of maximum compaction, human chromosomes range in size from about 2 to 10 micrometers in length.

- Chromosomes come in pairs of two.

Human has 46 chromosomes organized in 23 pairs.

- In idle phase chromosomes are not visible under the light microscope because they are extremely thin.

During cell division, mitosis or meiosis, they become compacted into shorter and thicker structures that can be seen under the microscope.

At this time they appear as paired rods with defined ends, called telomeres, and they remain joined at a constricted region, the centromere.