In forensics the science of investigating crimes paternity t

In forensics (the science of investigating crimes), paternity testing and the identification of human remains, biologists assume that populations are in HW equilibrium. This can become a matter of some significance in high-profile legal disputes. Consider this diagram of DNA fingerprint in which each band represents a specific DNA sequence. The different shading of the bands is used to symbolize 3 different genetic loci that were tested. A genetic locus is like a gene - it has a particular location and sequence on a chromosome but it may not code for a protein. Individual A has 2 bands for locus 1 (the solid black bands) while Individual B has only 1 band. Use the terms heterozygous and homozygous to explain this difference. Suppose the frequencies of the alleles are measured in a population and these data are obtained: A sample of blood from a crime scene shows the same banding pattern as Individual B. If the population is in HW equilibrium, what is the probability that the blood from the crime scene came from Individual B?

Solution

a. The DNA runs on the gel based on the size and genes showing only single band might have the same size of DNA. While DNA showing two bands will have DNA of different sizes. Based on this theory, we could say that individual A is heterozygous for the locus 1 as you can visualise two bands while individual B is homozygous for the locus 1 as only one band can be visualised.

b. The same pattern of a different locus in individual differs from person to person and no person would have same gene pattern. The probability of the blood from the crime scene came from the individual would be almost 99%.