Genetics and Genomics – DNA Fingerprinting Lab

Order Instructions/Description
For the assessed lab report

In your report you should include a copy (actual or scanned) of your gel photograph suitably labelled. Based on the data in this gel can you match one of the suspects to the sample left at the crime scene? (20 marks) Note that you do not need to include any details of how the experiment was performed.

In your report you should also answer the six questions below:

The DNA profiles in this experiment were compiled from four separate loci (on autosomal chromosomes) with multiple alleles at each locus. The relationship between the bands you observed and these four loci is shown in the figure below.

Question 1 (10 marks): From the above figure list the full genotype of the four suspects. Use the nomenclature A1 for allele 1 at locus A.

Question 2 (10 marks): The table below gives the number of times that each of the alleles present in our suspects are observed in the general population. From this allele frequency table calculate and list the frequency within the general population of each of these alleles. When the frequencies for each allele (at a given locus) are added together they do not reach 1 (100%), why is this?

Question 3 (20 marks): For each of the four suspects calculate the probability that another member of the general population would have the same DNA profile.

Question 4 (10 marks): If Ralph Tribano and Carrie Hoffman were to have a child together list one possible genotype that that child could have. During the investigation it was revealed that Lisa Dieta is actually the daughter of Ray Carlton. List a possible genotype of the mother.

Question 5 (10 marks): The “prosecutor’s fallacy” commonly crops up when considering DNA fingerprinting evidence. Consider the following scenario: DNA fingerprinting evidence from a crime scene in the UK indicates that 1 in 10,000 people will match the DNA profile found at the crime scene. For the purposes of this exercise assume that the frequencies of the alleles used do not deviate between different subpopulations of the UK, and that the crime was committed by someone from the UK. On DNA fingerprinting evidence alone what is the approximate probability that a suspect with a matching DNA profile is innocent of the crime? Explain your reasoning in 50 words or less.

Question 6 (20 marks): With the help of diagrams explain in 100 words or less how the extensive polymorphism observed in Variable Number Tandem Repeats (originally used for DNA Fingerprinting analysis) arises.