Hardy Weinberg Simulation
Case Study - Random Mating
In this simulation, you will simulate 5 generations of offspring beginning with a parental population that are all heterozygous. To represent alleles, you will use colored beads.
Red represents the dominant allele T and green represents the recessive allele t.
Place a bead in each hand and have your lab partner choose at random (without seeing the beads in your hand). You then do the same for your partner. The beads chosen represent the genotype of the next generation.
You will need to do this twice so that you always have 2 children created from a "mating". For the next generation, you will need to replace your beads with your offspring - in effect you play your offspring as the parents of the next generation.
Now that you are playing the offspring from your first mating. Find someone in the class at RANDOM to mate with again. To produce the second generation. Again you do this twice, so that you and your mate can both play the offspring for the next generation.
Now playing the offspring of the second generation, repeat the mating process again at random with anyone in the class. You will perform a total of 6 matings. At this point the class will need to report what their final genotypes are. When everyone is done, the teacher will tally the results on the board.
Initial Parental Population
p2 + 2pq + q2 = 1.0
25 + .50 + .25 = 1.0
Frequencies: TT ________ Tt _________ tt _________
Determine the number of T alleles present in the last generation:
Number of offspring with genotype TT _______________ x 2 = ______________ of A alleles
Number of offspring with the genotype Tt _____________x 1 = ______________ of A alleles
Total = _____________of T alleles
Determine the number of t alleles present in the last generation:
Number of offspring with genotype tt _______________ x 2 = ______________ of a alleles
Number of offspring with the genotype Tt _____________x 1 = ______________ of a alleles
Total = _____________of t alleles
Determine p and q
p = total number of T alleles divided by total number of alleles in population:
(Total number of alleles in population is the number of people in the class
x 2) p = _______________
q = total number of t alleles divided by total number of alleles in population:
(Total number of alleles in population is the number of people in the class
x 2) q = _______________
How does the final generation compare to the initial population in reference to the Hardy-Weinberg equation?
Case 2 - Selection
Initial Parental Population
p2 + 2pq + q2 = 1.0
25 + .50 + .25 = 1.0
In this case, you will modify the simulation to make it more realistic. In the natural environment, not all genotypes have the same rate of survival. In this simulation, you will assume that offspring who are homozygous recessive (tt) never survive. You will run this simulation similar to the last one, except that if your offspring is aa, it does not reproduce and contribute to the next generation. In order to keep the population size constant, parents must mate until they get two surviving offsring, either TT or Tt
Frequencies: TT ________ Tt _________ tt _________
Determine the number of T alleles present in the last generation:
Number of offspring with genotype TT _______________ x 2 = ______________ of A alleles
Number of offspring with the genotype Tt _____________x 1 = ______________ of A alleles
Total = _____________of T alleles
Determine the number of t alleles present in the last generation:
Number of offspring with genotype tt_______________ x 2 = ______________ of a alleles
Number of offspring with the genotype Tt _____________x 1 = ______________ of a alleles
Total = _____________of t alleles
Determine p and q
p = total number of T alleles divided by total number of alleles in population:
(Total number of alleles in population is the number of people in the class
x 2) p = _______________
q = total number of t alleles divided by total number of alleles in population:
(Total number of alleles in population is the number of people in the class
x 2) q = _______________
How do the new frequencies of p and q comapre to the initial frequencies in case 1?
In a large population would it be possible to completely eliminate a lethal recessive allele? Explain.