Question

The change of chromosomal parts between non homologous pairs of chromosome is

• A. Crossing over
• B. Translocation
• C. Inversion
• D. Transition

Answer 1

The correct option is B Translocation

Crossing over is the process of exchange of genetic material between non-sister chromatids of homologous chromosomes to produce new genetics combinations or variations. Rearrangement of the chromosomal segment between two non-homologous chromosomes is called as translocation; it differs from cross-over as it involves two non-homologous chromosomes while cross over includes a pair of homologous chromosomes which makes option A incorrect and B correct. Inversion is chromosomal mutation where a segment of a chromosome is reversed end to end. It occurs by introduction of break in single chromosome, its rotation by l80${}^o$ followed by its reinsertion in the same location; option C is incorrect. Transition is the substitution of one type of base by other of its own type. Hence, purine is replaced with purine (adenine to guanine and vice versa) and pyrimidine is replaced with pyrimidine (cytosine to thymine/uracil and vice versa) only; option D is incorrect.