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Three copies of chromosome 21 in a child...

Three copies of chromosome 21 in a child with Down's syndrome have been analysed using molecular biology technology to detect any possible DNA polymorphism with reference to different alleles located on chromosome 21. Results showed That out of 3 copies 2 of the chromosomes of the child contain the same alleles as one of the mother's alleles. Based on this when did the non-disjunction event most likely occur?

A

Paternal meiosis – I

B

Maternal meiosis - I

C

Paternal meiosis – II

D

Maternal meiosis – II

Text Solution

Verified by Experts

The correct Answer is:
B
Meiosis produces haploid gametes that contain one set of 23 chromosomes.
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Out of the three copies of chromosome 21 in a child, two have come from the mother .Based on this when did the nondisjunction event most likely occurred

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