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Biology 230

Polymerase Chain Reaction

(BIOL 230, Lab Experiment 20)

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This page is designed to help you interpret your experimental results.
Try a real application of PCR to diagnose a disease.
Do you need to review Hardy-Weinberg?

BioScience article

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Results

Samples from three different students are in lanes A, B, and C. The size ladder in D is in 100 bp increments (100, 200, 300, etc.)

Which student sample is homozygous for alu 550 bp? For alu 850 bp? Heterozygous for the two alu alleles?
*Primer-dimer artifacts: the primers can sometimes anneal to themselves and create small templates for PCR amplification - these are the so-called primer-dimer artifacts.

 

The following data are for alu alleles: A and B. You can be homozygous for 200, homozygous for 500, or heterozygous. There are two alleles for gene A: 200 bp and 500 bp; and for gene B: 100 bp and 400 bp.

Class Data

Genotype

715/715

715/415

415/415

Number

9

5

5
 

p2

2pq

q2

Actual

13 (0.41)

17 (0.53)

2 (0.06)

Expected

0.56

0..38

0.06

1. Do you think Alu is useful for distinguishing people in this class?

2. Would it matter if the two samples came from people who were closely related?

3. If the two genotypes were the same would that prove that the samples came from the same person?

4. If the PIC for the selected population and the Hardy-Weinberg population are different. What is the significance of this?