Consider three linked locis, SNP01, SNP02, and SNP03. The alleles at the respect
ID: 277691 • Letter: C
Question
Consider three linked locis, SNP01, SNP02, and SNP03. The alleles at the respective loci are D,d (SNP01), B and b (SNP02), and C and c (SNP03). Given the following table of haplotype counts:
What SNP is most likely in the middle of the other two SNPs in terms of ordering on a chromsome?
A. SNP02.
B. SNP03 is identical to SNP01.
C. SNP01.
D. SNPs 01 and 02.
E. SNP03.
Haplotype counts for three loci Phenotype Number of Observed haplotypes bcD 224 BcD 1 Bcd 603 BCd 422 bCd 4 BCD 1423 bCD 343 bcd 900Explanation / Answer
Answer: Option E is correct.
Explanation:
It is given that three loci are linked. So, these genes do not completely segregate independently of each other in their progeny. Hence the frequency of the parental genotypes is greater than the recombinants in the progeny.
Generally, the genotypes with the greatest number of progeny are considered as the parental types.
In the given case, highly represented genotypes in the progeny are BCD and bcd. Hence they are the parental types.
The least represented genotypes are considered as the double recombinants (BcD and bCd). These progeny genotypes can be double recombinants only when SNP03 (C or c) is located in between SNP01 and SNP02.