Question
HUMAN GENETICS QUESTION! PLEASE HELP!!
For each part of the question, you will need to use Excel to calculate what is asked. Plot the results as a graph. Do this in a single Excel file, with multiple worksheets. Incorporate the graph from Excel into your Word document. In this Word file you will explain in one or two or three sentences the results in your graph.
1. Imagine a locus with two alleles, A and a. Some population is fixed for the A allele. That is, the frequency of A is 1.0 and the frequency of a is 0.0. The mutation rate from A to a is 1/1,000,000. How will the frequency of A change over 1,000 generations? How do you feel about the results? 2. Same as question 1, but make the mutation rate 1/1,000 3. Imagine a locus with two alleles, A and a. Population X is fixed for the A allele, and Population Y is fixed for the a allele. Every generation, some individuals from Population Y migrate to Population X, so that every generation the new migrants make up 1% of the population. How does the frequency of the A allele in Population X change over 1,000 generations? 4. Imagine a locus with two alleles, A and a. The initial frequencies of these alleles are 0.6 and 0.4, respectively. If aa homozygotes all die without reproducing, how many generations will it take to decrease the frequency of the a allele to less than 1%? Assume that the Aa heterozygotes have the same fitness as the AA homozygotes. Include a graph of the change in frequency over time. Describe the rate of change over time Same data as question 4, but plot the change in mean fitness of the population over 100 generations. How do you feel about the results? 5. 6. Imagine a locus with two alleles, A and a. The initial frequencies of these alleles are 0.6 and 0.4, respectively. Heterozygotes are the most fit genotype. Homozygous AA individuals have a fitness of 0.9, while aa has a fitness of 0.4. After 100 generations, what will the frequency of a be? 7. Imagine a locus with two alleles, A and a. The initial frequencies of these alleles are 0.6 and 0.4, respectively. In this population there is underdominance at this locus, where the heterozygotes have a fitness of 0.9, and both homozygotes have fitness of 1. After 100 generations, what will the frequency of a be? 8. Same as question 7, but let the initial frequencies of A and a be 0.5 and 0.5, respectively 9. Same as question 7, but let the initial frequencies of A and a be 0.4 and 0.6, respectively 10. Comparing your results from questions 7-9, try different intermediate allele frequencies What general conclusions can you make regarding the behavior of alleles with underdominance? 11. Thinking about your results form 7-10, imagine a population with initial allele frequencies of 0.5 and 0.5. What if you also allow random genetic drift to operate in this population? What can you predict will happen to the allele frequencies over time?
Explanation / Answer
1) A) The basic formula is p2 + 2pq+q2 =1 and p+q = 1
p= frquency of dominante alleles in the population
q = frquency of recessive alleles population
p2 = percentage of homozygous dominant individuals
q2 = percentage of homozygous recessive individuals
2pq = percentage of heterozygous individuals
frequency of A =1.0
frequency of a =0.0
the mutationrate from A and a = 1/1,000,000 = 0.00001
if population is completely homozygous at locus a mutaton occures once in every 100 gametes to change A into a then in one generation
(mr)*(v+) mr = mutation rate, v+ = Frequency
0.00001*1.0 = 0.00001
After one generation 0.999 of the alleles will be A and 0.00001 will be a in generations increases
frequency of a will be 0.00001*0.999= 0.00000999
frequency of A will be 0.999-0.00000999 = 0.99899001
for 1000 generation frequecy of A = 0.99899001*1000 = 998.99001
2) A) mutation rate 1/1000 = 0.001
(mr)*(v+) = 0.001*1.0 = 0.001
