Question

What is the number of pairs of (i) chromosomes (ii) autosomes in humans? How many sex chromosomes are present in males and females respectively?

Answer 1

Hint: Chromosomes are made up of DNA and proteins. These are thread like-structures found within the nucleus of almost all the eukaryotic organisms. The DNA within the chromosome is wrapped around proteins called histones. The centromere is the constriction point of the chromosome that divides it into two arms- the longer arm is called the q arm while the shorter one is called the p arm.

Complete answer:
Each eukaryotic species contains a definite number of chromosomes in its cells. In the species that reproduce sexually, the chromosomes are present in pairs (2n) within the somatic cell. However, in the sex cells, the chromosomes are haploid (n) in number i.e. half the diploid number present in normal body cells or somatic cells. There are two types of chromosomes- autosomes and sex chromosomes. The autosomes are the chromosomes that help in the inheritance of all the characters other than the sex-linked. The sex linked characters are inherited due to the sex chromosomes.

i) There are 46 chromosomes in human cells i.e. 23 pairs of chromosomes are present in humans.
ii) The number of pairs of autosomes 22 i.e. 44 autosomes is present within each human cells.

The number of sex chromosomes is the same in both males and females. Both contain one pair of sex chromosomes. However, in males, two types of sex chromosomes are present- one X and one Y while females contain two X chromosomes.

Note: The chromosomes are visible when the cells undergo division. They play an important role during the life span of an organism. As it carries the DNA, it is involved in the inheritance of genetic characters from one generation to the next. It is also responsible for variations and mutations. Chromosomes play a vital role during the cell division process and the formation of new daughter cells.