Question

Why are maternal and paternal copies of chromosomes termed homologs despite genetic differences between parents?

A) Chromosomes undergo processes of recombination ensuring genetic similarity between maternal and paternal copies, leading to the homologous designation.
B) The 99.9% genetic similarity in the sequence of chromosomal pairs warrants them being called homologs despite parent-specific differences and rare mutations.
C) Evolutionary genetics dictates that chromosomes from the father and mother should be virtually identical due to their evolutionary relationship.
D) Each chromosome pair encodes nearly identical genes except for parent-specific differences and rare mutations, accounting for their similarity.

Answer 1

Maternal and paternal copies of chromosomes are termed homologous due to possessing the same set of genes in the same order, structural similarity, and the ability to pair during meiosis. The crossover process during meiosis I recombines genetic material between homologs, preserving gene order but mixing alleles.

Step-by-step explanation:

Maternal and paternal copies of chromosomes are termed homologous chromosomes because they possess the same set of genes in the same linear order, despite originating from different parents. The term 'homologous' reflects on their structural similarity and functional capacity to pair during meiosis, which is essential for sexual reproduction. Each pair of homologous chromosomes consists of one chromosome inherited from the mother and one from the father, both containing the same types of genes but possibly differing in their form or alleles.

The process of recombination, or crossover, further illustrates the homologous nature of these chromosomes. Recombination occurs during prophase I of meiosis, where segments of genetic material are exchanged between the maternal and paternal homologs. This exchange does not alter the gene order but rather shuffles the alleles between the homologs, resulting in genetic variability in the gametes produced.

Consequently, although individual alleles may vary between homologous chromosomes due to mutations or different parental origins, their shared features and genetic recombination processes justify the categorization of maternal and paternal chromosomes as homologs.