Question 1.

Given three autosomal micro satellite loci (A, B, and C) with respectively 8, 12, and 10 alleles each in a particular population. How many different genotypes are possible for each of the loci?

_________ A __________ B ___________ C What formula did you use to calculate the number of genotypes/gene?

Answer 1.

Three loci are there. Total number of alleles = 8+12+10=30
Total number of genotypes is always 2^(alleles – genes)
So, 2^30-3= 2^27.

Question 2. 

1 in______________individuals It was found that a particular defendant was found to match the perpetrator’s DNA at all three loci. As consultant for the prosecution, you explain to the jury what the frequency of the overall genotype is in the population. (Assume all alleles are present in equal proportions.) What is it?

Answer 2. 

This has nothing to do with frequency of overall genotype in the entire population. By DNA fingerprinting, only the two DNA are compared to find out whether the two DNA match or not. Various genotypes are distributed in the population by independent assortment.

Question 3.

____________________ Not to be out-done, the lawyer for the defence points out how many people would be expected to have that particular genotype in the New York area, where the crime was committed. The population of the greater New York area is 22,000,000. How many individuals would likely match the perpetrator’ genotype at all three loci?

Answer 3. 

1/8*1/12*1/10 = 1/960 people will match the perpetrator’ genotype in all three loci.
That is equal to 1/960*22,000,000 ~22916