B. Incorrect! 64% is all non-mm types, including both MN and NN. C. Incorrect! 84% is all non-nn types, including MN and MM types.

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1 Genetics Problem Drill 23: Population Genetics No. 1 of For Polynesians of Easter Island, the population has MN blood group; Type M and type N are homozygotes and type MN is the heterozygous allele. Allele frequency for M is 0.6. Assuming the conditions of the Hardy-Weinberg Law are met, what proportion of the population has NN type? (A) 36% (B) 64% (C) 84% (D) 16% (E) 50% For blood type MM, it is 0.6*0.6 = 36%. 64% is all non-mm types, including both MN and NN. C. Incorrect! 84% is all non-nn types, including MN and MM types. D. Correct! f(m) = 0.6 f(n) = 0.4; therefore f(nn) = q 2 = = 0.16 =16%. There is no way to arrive at that percentage. Keep in mind that the frequency of the homozygous genotype equals the square of the frequency of that allele. (D)16%

2 No. 2 of A group of 1000 people splits away from a larger population and establishes a separate society. With respect to the MN blood types, the emigrants number: type M = 360, type MN = 390, type N = 250. Assuming this population meets the Hardy-Weinberg s Law, what is the allele frequency of M after 10 generations? (A) 36% (B) 40% (C) 60% (D) 50% (E) 64% 36% is the genotype frequency of M type, i.e., f(mm) = 36% 40% is the allele frequency for N. C. Correct! This is the allele frequency for M. 50% is the allele frequency for N. 64% is the genotype frequency for total MN and N. According to Hardy-Weinberg s Law, the allele frequency will not change if in equilibrium as a function of generations; therefore, the original allele frequency is the same after 10 generations. The original genotype frequency is: f(mm) = 360/1000 = 0.36; therefore, the original allele frequency is 0.6, i.e., 60%. (C)60%

3 No. 3 of The M and N allele can mutate back and forth; from M to N, the rate is 3X10-5, and from N to M is After many generations, the allele frequency will be fixed again. What will be the allele frequency for N then? (A) 0.25 (B) 0.30 (C) 0.50 (D) 0.75 (E) is the final frequency for M allele. No calculation can lead to this number. C. Incorrect! The M and N allele cannot be equal because there will always be more N allele (more mutation from M to N than from N to M). D. Correct! This is calculated by the formula: 3*10-5 /(3+1)*10-5 = is a wild-guess. This actually has nothing to do with the original allele frequency; it is only related to the mutation rates: p^ = μ μ + ν Which is 3*10-5 /(3+1)*10-5 = (D)0.75

4 No. 4 of Color blindness is a recessive trait linked to the X chromosome. In an isolated island, about 12% of men are color-blind. The percentage of color-blind women and carriers respectively are? (A) 1.4% and 2.8% (B) 1.4% and 6% (C) 6% and 21% (D) 2.8% and 21% (E) 1.4% and 21% 1.4% is the right answer for color-blind women, but the carrier rate is too low; carriers are 2pq, not 2p. Carrier rate is not calculated by ½*q, which is 6%. It is 2pq. C. incorrect! Color blindness in women is q 2, not 1/2p. Color blind women are q 2, not 2q 2. E. Correct! Color blindness is q 2 = = 1.4%; carrier = 2pq = 2*0.88*0.12 = 21% For X-linked trait in males, p+q = 1, in this case, p = = 0.88, q = This is also the allele frequency in women; therefore, women who are color blind will be q2 = 0.12*0.12 = 0.014, and the women carriers would be 2pq = 2*0.88*0.12 = 21%. (E)1.4% and 21%

5 No. 5 of In a population, there are about 5000 adult males and an equal number of adult females. Due to a viral infection, about ¼ of the adult males lost their reproduction ability. What is the effective population size for this group? (A) 8,750 (B) 10,000 (C) 8,571 (D) 6,250 (E) 5,000 The mistake in this one is that the effective population size is not simply a function of adding up the breeding male and female numbers. This is a similar mistake as in A, but there is a second mistake: the breeding males are reduced by ¼. C. Correct! Ne = (4 x Nf x Nm)/ (Nf + Nm) = 4*5000*3750/( ) = There is no way to arrive at this number. This is the effective female number. The effective population size is Ne = (4 x Nf x Nm)/ (Nf + Nm). Here, Nf = 5000 and Nm = 4/3 *5000 = Therefore, Ne = 4*5000*3750/( ) = (C)8,571

6 No. 6 of What are the assumptions necessary for the Hardy-Weinburg law to be true? (A) A population under study is infinitely large. (B) Mating is strictly regulated and organized. (C) Natural selection is slow and does not influence the population under study. (D) The mutations occur at a normal frequency. (E) The mutation rates are at a low, fairly constant level. A. Correct! A population under study is infinitely large. The mating is random. C. Incorrect! The assumption is that there is no natural selection taking place. The law is based on the assumption that there are no mutations occurring. The law is based on the assumption that there are no mutations occurring. The genotype frequencies of a large, randomly mating population remains constant, provided immigration, mutation, and selection do not take place. (A)A population under study is infinitely large.

7 No. 7 of Which of the following is not a method used to measure genetic variation? (A) Isozymes by protein electrophoresis. (B) RFLP. (C) Small non-protein molecules (SNPs). (D) Minisatellites. (E) Microsatellites. This is a method used to measure genetic variation. Restriction length polymorphisms (RFLP) are also a method used. C. Correct! SNPs stands for Single Nucleotide Polymorphisms. Minisatellites are used. Microsatellites are also used for genetic variation calculations. Measuring genetic variation is done using a variety of molecular biological techniques. Measuring Methods include: - Isozymes by protein electrophoresis - Restriction Fragment Length Polymorphisms (RFLPs) - Minisatellites - Microsatellites (STRs) - DNA sequence - Single-stranded Conformation Polymorphism (SSCP) - Random Amplified Polymorphic DNAs (RAPDs) - Amplified Fragment Length Polymorphisms (AFLPs) - Single Nucleotide Polymorphisms (SNPs) (C)Small non-protein molecules (SNPs).

8 No. 8 of What is a polymorphism with respect to genetic variation? (A) It is the percent of loci or nucleotide positions showing more than one allele or base pair. (B) It is the percent of loci or nucleotide position that is identical. (C) A polymorphism is the base pair difference between two homologous sequences. (D) It is a measure of the percent of individuals that are heterozygous. (E) A polymorphism is the diversity of different alleles within a population. A. Correct! In terms of genetic variation, a polymorphism is the percent of loci or nucleotide positions showing more than one allele or base pair. In terms of genetic variation, a polymorphism is the percent of loci or nucleotide positions showing more than one allele or base pair. C. Incorrect! This is the definition of genetic distance. Heterozygosity (H) is a measure of the percent of individuals that are heterozygous. Allele diversity is defined as the diversity of different alleles within a population. In terms of genetic variation, a polymorphism is the percent of loci or nucleotide positions showing more than one allele or base pair. (A)It is the percent of loci or nucleotide positions showing more than one allele or base pair.

9 No. 9 of What processes are responsible for evolutionary change? (A) There is no evolutionary change due to the Hardy-Weinberg equilibrium. (B) Migration and a lack of mutations. (C) Migration and change in the genetic make-up. (D) A lack of migration is required for evolutionary change. (E) Mutation, migration and stable genetics contribute to evolutionary change. Most populations do not meet the Hardy-Weinberg equilibrium because the gene pool evolves. Mutations do contribute to evolution. C. Correct! Genetic drift is a process of evolutionary change. Migration is a part of the process of evolutionary change. Mutation, migration, natural selection and genetic drift contribute to evolutionary change. Most populations do not meet Hardy-Weinberg equilibrium conditions; allele frequencies change and the population s gene pool evolves. Four processes are responsible for evolutionary change: - Mutation - Genetic drift - Migration - Natural selection (C)Migration and change in the genetic make-up.

10 No. 10 of Which statement about genetic drift is correct? (A) Genetic drift is a change in allelic frequency due to the overlying genetics. (B) Genetic drift is a random change in allelic frequency due to chance. (C) Genetic drift is also called the Hardy-Weinberg principle. (D) The changes in genetic makeup are caused by an infinite size in the population. (E) In comparing two populations, one bigger than the other, genetic drift will impact both equally. Genetic drift is a random change in allelic frequency due to chance. B. Correct! Genetic drift is a random change in allelic frequency due to chance. C. Incorrect! Genetic drift is also known as the Sewall Wright Effect and its contribution. In fact, no population is infinite in size. In general, the smaller the population, the bigger the effect of genetic drift. Genetic Drift is a random change in allelic frequency due to chance; it is also called Sewall Wright Effect because of his contribution to this theory. Remember that no population is infinitely large and the smaller the population, the bigger the effect of genetic drift, e.g. the bigger the effect from random factors. (B)Genetic drift is a random change in allelic frequency due to chance.