Question

With the help of a neat labelled diagram, describe the structure of chromosome.

Answer 1

1. Chromosomes are highly condensed and therefore are clearly visible in metaphase stage of cell division.
2. A typical chromosome consists of two chromatids joined together at centromere also known as primary constriction.
3. Primary constriction consists of a disk shape plate called kinetochore. During cell division, spindle fibres get attached to the kinetochore.
4. Apart from primary constriction, some few chromosomes possess additional one or two constrictions called secondary constriction.
5. At secondary constriction I (nucleolar organizer), the nucleolus becomes organized during interphase.
6. A satellite body (SAT body) is attached at secondary constriction II, in very few chromosomes.
7. Each chromatid in turn contains a long, unbranched, slender, highly coiled double-stranded DNA thread, called chromonema, extending through the length of the chromatid.
8. The ends of the chromosome (i.e. chromatids) are known as telomeres.

Structure of Chromosome-