Question

Two couples had a dispute of parentage over a child and had filed a case. The judge had asked both the couples along with the child to go for DNA fingerprinting. The results of electrophoresis are as shown below. Which of the couple is the right parents of the child?

• A. $\left(F_1\right),\left(M_1\right)$
• B. $\left(F_1\right),\left(M_2\right)$
• C. $\left(F_2\right),\left(M_2\right)$
• D. $\left(F_2\right),\left(M_1\right)$

Answer 1

Answer: (A)

DNA profiling is a technique by which individuals are identified on the basis of their respective DNA profiles. Within the non-coding region of an individual's genome, there exists satellite DNA - long stretches of DNA made up of repeating elements called short tandem repeats (STRs). These repeating sequences can be excised to form fragments, by cutting with a variety of restriction endonucleases (which cut DNA at specific sites). As individuals all have a different number of repeats in a given sequence of satellite DNA, they will all generate unique fragment profiles. These different profiles can be compared using gel electrophoresis. Children inherit half of their alleles from each parent and thus should possess a combination of their parents alleles. Hence the child in the question contains 2 alleles - one from F1 and other from M1. Thus the parents of C are F1 and M1.

Therefore, the correct answer is option A.