Lecture 28 - Quantitative Genetics and Complex Disease

Question 1

Differentiate between qualitative and quantitative traits.

L28 S4

Answer 1

Qualitative (discontinuous):

• traits that possess only a few phenotypes
• i.e. flower color

Quantitative (continuous):

• traits that possess many phenotypes on a scale that can have overlapping
• complex relationship between phenotype and genotype, typically polygenic and/or has environmental factors
• i.e. height

Question 2

What is a regression coefficient?

L28 S28

Answer 2

Slope of a regression line.

Indicates how much one value changes on average per increase in another variable.

Question 3

What is narrow senses heritability?

L28 S33

Answer 3

Ratio of additive genetic variance to the total phenotypic variance.

Question 4

Heritability is tied to populations not individuals or traits. That heritability changes between populations.

L28 S36

Answer 4

Important detail

Question 5

What are quantitative trait loci (QTL)?

L28 S38-39

Answer 5

Selective breeding both for and against a trait and then comparing the two after several generations to see where the differences are.

This can be used to identify the genes that are responsible for the trait that was being selected for/against.