procedure for case study 1 random mati

Procedure for Case Study 1-Random Mating
You will start by placing 75 light-colored beans and 25 dark-colored beans into a bag. The 100 beans represent your initial gene pool. The light beans represent the F alleles, and the dark beans represent the f alleles. This is the gene pool produced by mating between heterozygous (Ff) and homozygous normal (FF) individuals.
Use the following to determine the number of dominant alleles in the population and the same formula to determine the number of recessive alleles in the population. number of offspring with genotype FF (two dark beans) _____ × 2 = _____ F alleles number of offspring with genotype Ff (one dark one light) ______ × 1 = _____ F alleles
Total F alleles = ______ p = Total number of F alleles / Total number of alleles in population (Total number of beans you used)
Practice determining the initial allele frequencies (p and q) for both the F and f alleles. Use the same formula for finding recessive alleles, but change the top number to genotype ff × 2. Check your initial frequencies using the chart below.
Chart 1 (example data chart)
Allele Frequencies

Allele F
Allele f
Generation
Number
Percentage
Frequency
Number
Percentage
Frequency
Start
75
75
0.75
25
25
0.25
1

2

3

4

5

6 (if needed)

1. Before you begin, make a prediction about what you expect to observe regarding this population's allele frequency over several generations. Record your hypothesis in your lab report.
2. Shake up the 100 beans to simulate random mixing of the gametes during the first generation of reproduction.
3. Without looking, reach into the bag and take out two beans. This is the first individual (with two alleles).
4. As you pick the individuals, record your results on a sheet of paper. FF (two light beans), Ff (light and dark), and ff (two dark).
5. Put the selected beans back into the bag and repeat the procedure 49 more times to select all 50 individuals (100 alleles in the gene pool). Remember not to look when you select the two beans.
6. Record your results in the data chart. The 28 FF data row is an example. Please record your own data instead.
7. After you determine the percentages, add in the necessary beans to return the gene pool to 100 alleles, but with the resulting percentages from Trial 1. For example, if your percentage of dominant alleles changed to 80%, then you would add 5 dominant beans (75 original + 5 new = 80) and remove 5 recessive beans. Why? Because the new recessive percentage would be 20%, you originally had 25 beans, so you would remove 5 = 20 beans.
8. Trial 2 will be done in the same manner (repeat steps 2–8). Be sure to select the individuals without looking, record your results, and then replenish the gene pool to 100 alleles with the percentages you calculate at the end of the trial.
9. Continue for five trials. Be sure to record your results each time.
10. Use the data from the five trials to plot the frequency of the "f" allele on your graph paper. (If you do not get a population with H-W equilibrium on the fifth trial, you will need to do a sixth trial.)
11. Now that you have collected data on your own, be sure to share with your partner(s) to compile within the lab report.