quantitative genetics - lecture 16

Question 1

What are the components of phenotypic variation?

Answer 1

Vp = Vg + Ve + Vge

Question 2

What are the components of genetic variation?

Answer 2

Additive genetic variance ( heritable) + Dominance ( non - inheritable) +gene interaction ( non - inheritable)

Question 3

what are the two types of heritability?

Answer 3

Broad sense and Narrow sense

Question 4

definition of broad sense heritability

Answer 4

The proportion of phenotypic variation attributable to genetic differences between individuals

Question 5

broad sense formula

Answer 5

H^2 = Genetic variance/ Phenotypic variance

Question 6

Narrow sense formula

Answer 6

h^2= Additive genetic variance/phenotypic variance

Question 7

Phenotypic correlation

Answer 7

When points represent different individuals

Question 8

Genotypic correlation

Answer 8

When points represent different genotypes

Question 9

Pleiotropy

Answer 9

When a single gene affects multiple characteristics/ traits

Question 10

What is Linkage disequilibirum?

Answer 10

Linkage disequilibirm occurs when there is an association between alleles at different loci ( e.g allele A tends to be found with B)

Question 11

coupling gamates vs replusion gametes

Answer 11

coupling - similiar traits together

repulsion - dissimilar traits together

Question 12

What happens if there is an overrepresentation of coupling and repulsion gametes?

Answer 12

Then there is a linkage disequilibrium

Question 13

what dos coupling do?

Answer 13

A and B are more likely to be inherited, therefore there is correlation between height and foot size

Question 14

Why is linkage disequilibirum an unlikely explanation for most genetic correlations?

Answer 14

recombination removes linkage disequilibirum

Question 15

What happens when recobination occurs ni an individual that is heterozygous at only one locus( single heterozygote)?

Answer 15

No new haplotypes are produced

Question 16

What happens when recombination occurs in a double heterozygote?

Answer 16

New haplotypes are produced

Question 17

How do you find the genetic basis to variation?

Answer 17

• Mapping quantitative trait loci

- Genome - wide studies

Question 18

Whatt is a QTL?

Answer 18

A Quantitative Trait Locus (QTL) is a location in the genome that causes different values of the trait in question

Does not have to be a gene

Question 19

What are QTL’s associated in the genome?

Answer 19

Not Associated with differences in proteins , but rather , differences in gene expression

Question 20

How to do QTL anaylsis?

Answer 20

• Test whether different genotypes have different trait values
• done using gnetic markers
• Identify casual variation linked to thse markers

Question 21

What is the prupose of QTL?

Answer 21

Quantitative trait locus (QTL) analysis is a statistical method that links two types of information—phenotypic data (trait measurements) and genotypic data (usually molecular markers)—in an attempt to explain the genetic basis of variation in complex traits

Question 22

What is Genome Wide Association study ?

Answer 22

Identifies casula loci by testing whether groups with different phenotypes have different frequencies of alleles at a locus

Question 23

what does vG stand for?

Answer 23

Genetic variation

Question 24

What does Ve stand for?

Answer 24

Environmental variation

Question 25

What does Veg stand for?

Answer 25

Genotype - environmental variation

Question 26

What is the formula for genetic variation

?

Answer 26

Va + Vd + Vi

Question 27

What does Va stand for?

Answer 27

Additive genetic variance

Question 28

What does Vd stand for?

Answer 28

Dominance genetic variance

Question 29

What does Vi stand for?

Answer 29

Gene interaction variance

Question 30

Definition of narrow sense heritability

Answer 30

theproportionof phenotypic variation that contributes to the resemblance between parents and offspring