Q.42 For a gene present on human chromosome 4, the maximum number of alleles that may be detected
by sequencing the genome of 5 males and 10 females is ______.Chromosome 4 in humans is an autosome, so both males and females carry two copies of any gene on it. Sequencing genomes from 5 males (each with 2 alleles) and 10 females (each with 2 alleles) provides a total of 30 alleles, allowing detection of up to 30 distinct variants if all differ.
Correct Answer
The maximum number of alleles detectable is 30.
Detailed Explanation
Humans have 22 pairs of autosomes, including chromosome 4, which are identical in males (XY) and females (XX). Each individual contributes two alleles per autosomal gene—one from each homologous chromosome. With 15 people total (5 males + 10 females), the sample yields 15 × 2 = 30 alleles. Sequencing detects all unique variants among these, assuming no identical alleles across individuals.
Why Chromosome 4 Matters
Unlike sex chromosomes (X or Y), chromosome 4 lacks dosage compensation or hemizygosity issues. Males have no single-copy constraint here, matching females’ diploid state. This uniformity maximizes allele diversity detection equally from both sexes.
Option Analysis
Typical multiple-choice options for such questions might include:
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20: Counts only females (10 × 2), ignoring males’ alleles—incorrect, as males contribute equally.
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25: Adds males incorrectly (e.g., 5 males as 5 alleles + females), overlooking diploidy.
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30: Correct total (15 individuals × 2 alleles).
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35: Overcounts, perhaps treating males as having extra copies—impossible for autosomes.
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Genetic Implications
In population genetics, larger samples increase rare allele detection, vital for studies in molecular biology and evolution. For researchers in Kota, Rajasthan, this principle applies to local genomic sequencing projects.
