Question

Define Homologous chromosome.

Answer 1

Chromosomes are small fine structures present in the nucleus of both plant and animal cells and it is made up of proteins and one deoxyribonucleic acid (DNA).

Complete answer:
-Homologous chromosome also known as Homologs is made up of two chromosomes, one maternal (from mother) and the other paternal (from father), Both chromosomes get paired during fertilization.
-The homologous chromosome has certain points on the chromosome where it gets paired so that they are paired and aligned properly and are not separated before meiosis.
-The Homologous chromosomes show the same length, even the centromere position is the same on both chromosomes, hence they are structurally the same so that they can pair up easily and they show identical staining for genes located at the same location on the chromosome.
-The diploid organisms show only one pair of Homologous chromosomes out of which one is inherited from the mother and the other is inherited from the father.
-The alleles on the Homologous chromosomes may not be the same which results in different phenotypes of the offspring.
-During meiosis crossing over takes place between the homologous chromosome which leads to the mixing of traits of both the chromosomes.
-The offspring produced have a new combination of alleles due to recombination of the Homologous chromosome.

Note:
-Thomas morgan concluded from the testcross experiments that the alleles are more closely placed in the Homologous chromosomes.
-Homologous chromosomes are two different chromosomes whereas sister chromatids are two parts of the same chromosome and are identical to each other.
-Humans have a total of 46 chromosomes that are 23 pairs out of which only 22 pairs are autosomal homologous chromosome pairs and the remaining pair is of sex chromosomes.