Question

The long and short arms of the chromosomes are designated respectively as
(a) p and q arms
(b) q and p arms
(c) m and p arms
(d) l and s arms

Answer 1

Hint: All human chromosomes have 2 arms like structures, a short arm, and a long arm. The two arms are separated by the centromere (the point at which the chromosome is attached to the spindle during cell division).

Complete answer:
The long and short arms of the chromosomes are known as q and p arms, respectively. The symbol ‘p’ was chosen to represent the short arm because ‘p’ stands for ‘petit’, ‘small’ in French. The letter ‘q’ was selected to represent the long arm because ‘q’ is the next letter to ‘p’ in the English alphabet.
- Chromosomes are made of DNA and histone proteins within the nucleus of almost every cell in our body.
- There are 23 pairs of chromosomes found in human beings. One set of chromosomes comes from the mother and another set comes from the father.
- The 22 pairs of chromosomes are called autosomes found in the somatic cells but the 23^rd pair are sex chromosomes, responsible for the gender of a person.
- These nucleosomes coil up to create chromatin loops and the chromatin loop wraps around each other to form a chromosome.
- Chains of DNA molecules form genes in the chromosome.
- At the end of the chromosomes is known as a telomere.
- The function of chromosomes is to transfer the genetic information from the mother and father to their children.

So, the correct answer is, ‘p and q arms.’

Note: The loss of part of 5p (the short arm of chromosome 5) results in ‘Cri du Chat syndrome’ (the cry of the cat sound) . An extra copy of part of 21q, the long arm of chromosome number 21, causes Down syndrome.