Question

Distinguish between X and Y chromosomes.

Answer 1

Humans usually have 23 pairs of chromosomes i.e. a total of 46 chromosomes. The autosomes (1-22 chromosome pairs) are the same in males and females. Females have two X chromosomes, whereas males have an X chromosome and a much smaller Y chromosome.

Complete step-by-step answer:
The molecule of a DNA (deoxyribonucleic acid) which contains a part or all of the genetic material of an organism is called Chromosome and pair 23 is dissimilar for males and females.
Difference between the X chromosome and Y chromosome:

X chromosome	Y chromosome
Appear as X shape as they are metacentric and are longer compared to the Y chromosome.	Appear as Y shape as they are acrocentric and are shorter compared to the X chromosome.
It contains a large amount of euchromatin (a lightly packed form of chromatin).	It contains a small amount of euchromatin.
It contains a small amount of heterochromatin (condensed chromatin structure).	It contains a large amount of heterochromatin.
There is a large amount of DNA or active genes present in the X chromosome.	There is a small amount of DNA or active genes present in the Y chromosome.
The X chromosome contains over 1000 genes	The Y chromosome contains nearly 78 genes.
Genes present in the X chromosome shows criss cross inheritance.	Genes present in the Y chromosome shows linear inheritance.
X chromosomes are found in both genders.	Y chromosomes are found only in males.

Note: Multicellular organisms have special cells called gametes for reproduction which contain only half the number of chromosomes. So when gametes from two different parents combine during reproduction, it results in a new individual, which contains DNA (the genetic material passed from parents) and a re-established number of chromosomes. This process is done by many species to produce their offspring as it is the only means to ensure the continuity of a species.