BIOL 3301 Genetics Exam 2 study guide
questions and answers (with prof Meisel &
Dauwalder) University of Houston
,what are the effects of "gene flow"?
1. Change allele frequencies by
migration into a population
2 Equalize allele frequencies between
two populations
How do we quantify the amount of invbreeding?
Calculate the probability for A1 allele IBD
Calculate the probability for A2 allele IBD
IBD=Identical by descent
F=inbreeding coefficient
half sibling mating=2*(1/2)^4
first cousins=4*(1/2)^6
HWE for more than two alleles
AA=p^2
Ai=2pr
BB=q^2
Bi=2qr
AB=2pq
ii=r^2HAT BRINGS BACK A POPULATION TO HWE?
University of Houston Fall 2018 Exam 2 (3301)
Chapters 7, 10, 19-20
Quantitative Traits
1. Have continuous variation
2.integration of incomplete dominance and GenexEnvironment intxns
3.when you cannot assign an individual to a discrete category
How do you characterize phenotypic variation?
1. Average: (mean,median,mode)
2.Variation: variance (s^2) variation around mean.
look at pp ch.19 slide 5 for the graphs
What causes the variation in
height across individuals?
, A. Differences in genotypes
B. Environmental differences
C. Genetic and environmental differences
additive traits
1. identify number of loci
2. possible true breeding genotypes
3.Add up the number of A1 & B1
alleles to get the trait
4.The number of phenotypes increases
rapidly (Pascal's rule = 2n + 1)
how to calculate number of phenotypes for additive traits?
Pascal's rule 2n+1
what happens when you increase the number of genes controlling a trait?
As you increase the number of genes
controlling a trait, the phenotypic
distribution looks more continuous
what is the outcome of inheritance of continuous traits?
F1:intermediate between parental traits but the mean is dependent on ENVIRONMENTAL
variation ONLY.
F2: same mean as F1 but more variance and the variation is dependent on GENETIC and
ENVIRONMENTAL variation.
F3: can recover parental genes depending on what you cross your F2 with.
Why don't all true breeding "short" plants have the same length corolla?
A. Environment also affects corolla length.
B. Still some genetic variation remaining for corolla length.
C. There are some non-additive effects on corolla length.
D. All of the above are possible explanations.
Phenotypic Variance formula (Vp)
Vp=Vg+Ve
Environmental effects on continuous genetic variation
questions and answers (with prof Meisel &
Dauwalder) University of Houston
,what are the effects of "gene flow"?
1. Change allele frequencies by
migration into a population
2 Equalize allele frequencies between
two populations
How do we quantify the amount of invbreeding?
Calculate the probability for A1 allele IBD
Calculate the probability for A2 allele IBD
IBD=Identical by descent
F=inbreeding coefficient
half sibling mating=2*(1/2)^4
first cousins=4*(1/2)^6
HWE for more than two alleles
AA=p^2
Ai=2pr
BB=q^2
Bi=2qr
AB=2pq
ii=r^2HAT BRINGS BACK A POPULATION TO HWE?
University of Houston Fall 2018 Exam 2 (3301)
Chapters 7, 10, 19-20
Quantitative Traits
1. Have continuous variation
2.integration of incomplete dominance and GenexEnvironment intxns
3.when you cannot assign an individual to a discrete category
How do you characterize phenotypic variation?
1. Average: (mean,median,mode)
2.Variation: variance (s^2) variation around mean.
look at pp ch.19 slide 5 for the graphs
What causes the variation in
height across individuals?
, A. Differences in genotypes
B. Environmental differences
C. Genetic and environmental differences
additive traits
1. identify number of loci
2. possible true breeding genotypes
3.Add up the number of A1 & B1
alleles to get the trait
4.The number of phenotypes increases
rapidly (Pascal's rule = 2n + 1)
how to calculate number of phenotypes for additive traits?
Pascal's rule 2n+1
what happens when you increase the number of genes controlling a trait?
As you increase the number of genes
controlling a trait, the phenotypic
distribution looks more continuous
what is the outcome of inheritance of continuous traits?
F1:intermediate between parental traits but the mean is dependent on ENVIRONMENTAL
variation ONLY.
F2: same mean as F1 but more variance and the variation is dependent on GENETIC and
ENVIRONMENTAL variation.
F3: can recover parental genes depending on what you cross your F2 with.
Why don't all true breeding "short" plants have the same length corolla?
A. Environment also affects corolla length.
B. Still some genetic variation remaining for corolla length.
C. There are some non-additive effects on corolla length.
D. All of the above are possible explanations.
Phenotypic Variance formula (Vp)
Vp=Vg+Ve
Environmental effects on continuous genetic variation
