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.
List-I | List-II |
A. Metacentric chromosome | I. Chromosome has a terminal centromere |
B. Sub-metacentric chromosome | II. Middle centromere forming two equal arms of chromosome |
C. Acrocentric chromosome | III. Centromere is slightly away from the middle of chromosome resulting into two unequal arms |
D. Telocentric chromosome | IV. Centromere is situated close to its end forming one extremely short and one very long arm |
List-I | List-II |
A. Histones | III. Positively charged basic proteins |
B. Nucleosome | IV. DNA wrapped around histone octamer |
C. Euchromatin | I. Loosely packed chromatin |
D. Heterochromatin | II. Densely packed Chromatin |
List I | List II | ||
---|---|---|---|
A | Mesozoic Era | I | Lower invertebrates |
B | Proterozoic Era | II | Fish & Amphibia |
C | Cenozoic Era | III | Birds & Reptiles |
D | Paleozoic Era | IV | Mammals |