The Hardy-Weinberg Principle

General Biology Independent Laboratory Experiences for the College Science Major

Second Semester

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The Hardy-Weinberg Principle

Version 09-1.01

Exercise 1: The Hardy-Weinberg Equilibrium Model

Hitchhiker’s

Thumb Thumbs with end joints that can be bent back at 45 are 100% recessive (ss).

Thumbs that cannot bend back significantly are dominant (either SS or Ss). SS, Ss

ss

Students’ Results: 78 56

Results:

1. Use Example 1 as a guide and the students’ data above to determine the allelic frequencies for the gene using the equations proposed by Hardy-Weinberg to support the equilibrium theorem.

2. Show that the allelic frequencies will not change over time.

3. Suggest conditions that could change these frequencies. What would the effects of the conditions be?

Exercise 2: Evolution and Genetic Drift

Results:

Table 1: Student’s Results for an Ecological Study to Determine Genetic Drift Due to Selective Foraging Pressure by a Kestrel

generation # of brown

grasshoppers

B? # of green

grasshoppers

bb q2 q p P2 2pq

Y0

Y1

Y2

Y3

Y4

Y5

For purposes of calculation: Let p = the frequency of the dominant allele, B.

Let q = the frequency of the recessive allele, b.

? can denote either B or b. Why?