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

Human karyotypes categorize 23 chromosome pairs into 7 groups (A-G), primarily by size and centromere location, as follows:
1. Group A (Chromosomes 1–3): Comprises the largest chromosomes, featuring metacentric or near-metacentric centromeres.
2. Group B (Chromosomes 4–5): Consists of large chromosomes with submetacentric centromeres.
3. Group C (Chromosomes 6–12, X): Contains medium-sized chromosomes, all having submetacentric centromeres.
4. Group D (Chromosomes 13–15): Features medium-sized, acrocentric chromosomes, which also possess satellite structures.
5. Group E (Chromosomes 16–18): Includes small chromosomes; chromosome 16 is metacentric, while 17 and 18 are submetacentric.
6. Group F (Chromosomes 19–20): Represents small chromosomes, all with metacentric centromeres.
7. Group G (Chromosomes 21–22, Y): Encompasses the smallest chromosomes, all acrocentric. Chromosome Y is notably distinct due to its diminutive size.
This classification system facilitates the identification of chromosomal abnormalities during cytogenetic analysis.