Q.47 How many pairs of autosomal chromosomes are there in normal humans?
Normal humans have 22 pairs of autosomal chromosomes. These non-sex chromosomes carry genetic information unrelated to gender determination.
Question Analysis
The query “How many pairs of autosomal chromosomes are there in normal humans?” appears in CSIR NET Life Sciences exams, testing basic cytogenetics knowledge. Humans possess 46 chromosomes total, arranged as 23 homologous pairs in diploid somatic cells. Of these, 22 pairs (44 chromosomes) qualify as autosomes—numbered 1 through 22 based on decreasing size—while the 23rd pair consists of sex chromosomes (XX in females, XY in males).
Option Explanations
Exams often provide multiple-choice options like 44, 46, 22, or 23. Option 44 refers to total autosome count (incorrect for pairs). Option 46 denotes total chromosomes (ignores pair structure and autosome distinction). Option 23 matches total pairs (includes sex chromosomes). Only 22 correctly identifies autosomal pairs.
Humans maintain 23 pairs of chromosomes in somatic cells, totaling 46, with 22 pairs classified as autosomal chromosomes—non-sex chromosomes identical in males and females. These autosomes, labeled 1-22 by size, house most genes controlling traits like metabolism and development.
Autosomes vs. Sex Chromosomes
Autosomes transmit inherited traits unrelated to sex determination and appear homologous in both genders. Sex chromosomes (pair 23) differ: XX determines female, XY male. Karyotyping visualizes this arrangement, confirming 22 autosomal pairs via staining and microscopy.
Relevance for CSIR NET
CSIR NET Life Sciences candidates encounter this in genetics units, emphasizing diploid karyotype (2n=46). Errors like nondisjunction alter counts, causing disorders such as Down syndrome (trisomy 21). Mastery aids quantitative genetics and molecular biology problem-solving.
