Question
Biology Question on Genetics
Aneuploidy is a chromosomal disorder where chromosome number is not the exact copy of its haploid set of chromosomes, due to :
(a) Substitution
(b) Addition
(c) Deletion
(d) Translocation
(e) Inversion
Choose the most appropriate answer from the options given below
(c) and (d) only
(d) and (e) only
(a) and (b) only
(b) and (c) only
(b) and (c) only
Solution
Aneuploidy refers to an abnormal number of chromosomes, which is not a multiple of the haploid set. This arises due to errors during chromosome segregation in meiosis.
Addition (B) and Deletion (C): These directly lead to aneuploidy. Nondisjunction, where chromosomes fail to separate correctly, can result in the addition or deletion of chromosomes in gametes.
Substitution (A): Involves replacing one nucleotide with another and does not change the chromosome number.
Translocation (D): Involves the transfer of a segment of a chromosome to a nonhomologous chromosome. While potentially causing other genetic disorders, balanced translocations do not directly cause aneuploidy because the total number of chromosomes remains the same.
Inversion (E): A segment of the chromosome is reversed end-to-end. This doesn’t change
the chromosome number.