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1 Population Genetics (allele frequencies and Hardy-Weinberg equilibrium) January 2009

2 Not enough information
In a plant population, Frequency of allele A = 0.8 Frequency of allele a = 0.2 What might be the probability that any given pollen produced by these trees has the ‘A’ allele? 0.8 0.4 0.2 0.1 Not enough information Spring ’08 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Tin Tin Su and Dr. Michelle Smith 88% correct

3 R = ability to roll tongue r = cannot roll tongue
Tongue rolling R = ability to roll tongue r = cannot roll tongue In a population of 100RR, 100Rr and 100rr What is the frequency of allele R? A. 1.0 B. 0.66 C. 0.5 D. 0.33 Spring ’08 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Tin Tin Su and Dr. Michelle Smith 79% correct

4 Here is a population of chuzzels: 16 48 36
homozygous red chuzzels heterozygous red chuzzels homozygous green chuzzles aa AA Aa What is the frequency of allele A? A. 0.33 B. 0.4 C. 0.6 D. 0.64 E. 0.84 Fall ’08 Clicker Question used in MCDB 2150, Principles of Genetics, written by Drs. Michelle Smith and Ken Krauter 81% correct in Ken Krauter’s course

5 Early onset or infantile Tay-Sachs disease causes nerve cells deteriorate and then eventually die. The disease is inherited in an autosomal recessive manner. In a French Canadian community 9% (0.09) of the population has infantile Tay-Sachs. What is the chance that a man with no family information on the disease is a carrier (Aa) ? A. 4.5% B. 10.5% C. 15.5% D. 34% E. 42% Spring ’08 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Tin Tin Su and Dr. Michelle Smith 12% correct

6 Cohen Syndrome has several characteristics such as obesity, mental retardation, and facial abnormalities. The disease is inherited in an autosomal recessive manner. In an Old Order Amish community 4% (0.04) of the population has Cohen Syndrome. If there is no information about whether this disease runs in the family, what is the chance that a disease free man is NOT a carrier (AA)? 64% 32% 10% 4% 2% Spring ’08 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Tin Tin Su and Dr. Michelle Smith 50% correct

7 Chuzzle Population A chuzzle populations contains 640 red chuzzels and 320 green chuzzles. Chuzzles are not choosy about their mates. Either color will mate with the other at equal frequencies. When red chuzzles mate all the pups are red. When red and green chuzzles mate some pups are red and some are green. There is no advantage (for mating or survival) based on color. Spring ’08 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Christy Fillman. Which trait is dominant? A) red B) green

8 Chuzzle Population You want to make some predictions about the chuzzle population. Will there be the same percent of red and green chuzzles in the next generation? A) yes B) no Spring ’08 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Christy Fillman.

9 Consider a punnett square looking at the population of chuzzles.
Now, let’s consider the gametes: Which gametes produced which offspring? a A homozygous red chuzzels heterozygous red chuzzels Aa AA homozygous green chuzzles heterozygous red chuzzels 36% Aa aa Spring ’08 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Christy Fillman. What is the probability of creating an aa gamete? 36% or .36 What is the probability of getting an ‘a’ in a gamete? A) C) .36 B) D) .6

10 Consider a punnett square looking at the population of chuzzles.
.6 homozygous red chuzzels heterozygous red chuzzels A Aa AA homozygous green chuzzles heterozygous red chuzzels .6 a 36% Aa aa q Spring ’08 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Christy Fillman. q = .6 = ‘a’ frequency What is the frequency of the ‘A’ allele? A) C) .6 B) D) .4

11 p + q = 1 (a frequency) + (A frequency) = 1
Consider a punnett square looking at the population of chuzzles. p A .4 q a .6 homozygous red chuzzels heterozygous red chuzzels .4 A p Aa AA homozygous green chuzzles heterozygous red chuzzels .6 a 36% Aa aa q Spring ’08 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Christy Fillman. p + q = (a frequency) + (A frequency) = 1 What is the frequency of the AA genotype? (probability of being AA)? A) C) .25 B) D) .64

12 p + q = 1 (a allele frequency) + (A allele frequency) = 1
Consider a punnett square looking at the population of chuzzles. p A .4 q a .6 homozygous red chuzzels heterozygous red chuzzels .4 A p Aa AA 16% p^2 homozygous green chuzzles heterozygous red chuzzels .6 a 36% Aa aa q q^2 Spring ’08 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Christy Fillman. p + q = (a allele frequency) + (A allele frequency) = 1 p^2 = AA genotype frequency = .4 X .4 = .16 q^2 = aa genotype frequency = .6 X .6 = .36 What is the frequency of the Aa genotype? A) pq C)p^2 X q^2 B) 2 pq D)p^2 + q^2

13 Some Questions: A man comes from a family with cystic fibrosis (CF). He has a brother with the disease, but he and his parents are not affected. The man’s wife comes from a family with no history of CF. Her probability of being a carrier of this recessive trait is the same as the rest of the population wherein 1 in 2500 births are infants with CF. What is his probability of being a carrier (solved using Mendelian genetics)? B C. 0.5 D E. 0.75 Spring ’07 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Mark Winey

14 Some Questions: A man comes from a family with cystic fibrosis (CF). He has a brother with the disease, but he and his parents are not affected. The man’s wife comes from a family with no history of CF. Her probability of being a carrier of this recessive trait is the same as the rest of the population wherein 1 in 2500 births are infants with CF. 2. What is her probability of being a carrier (solved using Hardy-Weinberg law)? A B C D E Spring ’07 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Mark Winey

15 Some Questions: A man comes from a family with cystic fibrosis (CF). He has a brother with the disease, but he and his parents are not affected. The man’s wife comes from a family with no history of CF. Her probability of being a carrier of this recessive trait is the same as the rest of the population wherein 1 in 2500 births are infants with CF. 3.What is the probability that they will have a child with CF? B C D Spring ’07 Clicker Question used in MCDB 2150, Principles of Genetics, written by Dr. Mark Winey


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