Question

In the human karyotype, chromosomes are divided into how many groups?

• A. 3 groups
• B. 5 groups
• C. 7 groups
• D. 9 groups

Hint:

Focus on the classification of human chromosomes based on size and centromere position for karyotype analysis.

Answer 1

The Correct Option is C

In the human karyotype, the 23 pairs of chromosomes are classified into 7 groups (A to G) based on their size and the position of the centromere. This classification is as follows:
1. Group A (Chromosomes 1–3): Largest chromosomes with metacentric or nearly metacentric centromeres.
2. Group B (Chromosomes 4–5): Large chromosomes with submetacentric centromeres.
3. Group C (Chromosomes 6–12, X): Medium-sized chromosomes with submetacentric centromeres.
4. Group D (Chromosomes 13–15): Medium-sized chromosomes with acrocentric centromeres and satellite structures.
5. Group E (Chromosomes 16–18): Small chromosomes with either metacentric (16) or submetacentric (17–18) centromeres.
6. Group F (Chromosomes 19–20): Small chromosomes with metacentric centromeres.
7. Group G (Chromosomes 21–22, Y): Smallest chromosomes with acrocentric centromeres; Y is unique due to its small size.
This grouping aids in identifying chromosomal abnormalities during cytogenetic analysis.