37. In human karyotype, X chromosome belongs to which group?
- A group
- B group
- C group
- D group
The X chromosome in human karyotype belongs to group C, based on the Denver classification system used in cytogenetics.
Human Karyotype Basics
Human cells have 46 chromosomes in 23 pairs: 22 autosome pairs (A-G groups) and one sex chromosome pair (XX/XY).
The 1956 Denver classification groups them by size, centromere position, and morphology using G-banding.
Group C includes medium-sized submetacentric chromosomes: pairs 6-12 plus X (and sometimes noted with 13 variably).Correct Answer: C Group
X chromosome is submetacentric, medium-length (~155 Mb, ~5% genome), fitting group C morphology alongside chromosomes 6-12.
This classification aids karyotyping for disorders like Turner syndrome (45,X).
Y is acrocentric in group G.Group Breakdown
Option Chromosomes Included Key Features Includes X? A group 1-3 Largest, metacentric (1,3); acrocentric (2) No B group 4-5 Large, submetacentric No C group 6-12 + X Medium submetacentric Yes D group 13-15 Medium-large acrocentric No Classification Criteria
Groups rely on size (long/short arms ratio) and centromere position: metacentric (p≈q), submetacentric (p<q), acrocentric (very short p arm).
X matches C: submetacentric like 6-12, distinct from larger A/B or acrocentric D/E/G.
Modern FISH/CGH refines but retains Denver for standard exams.
