Q.Compare the X-chromosome and the Y-chromosome.

A typical metaphase chromosome (chromosomes are most visible and condensed at this stage) consists of two sister chromatids joined at a primary constriction called the centromere, whose disc-shaped kinetochore is where spindle fibres attach during cell division. Each chromatid contains a long, coiled, unbranched double-stranded DNA thread called the chromonema, studded with chromomeres, running the full length of the chromatid; the free ends are called telomeres. Some chromosomes carry additional secondary constrictions — secondary constriction I is where the nucleolus reorganises during interphase, and a small satellite (SAT) body is occasionally attached beyond secondary constriction II. …