21 | QUANTITATIVE GENETICS AND MULTIFACTORAL TRAITS

Question 1

It should be emphasized that HERITABILITY indicates…..

Answer 1

-neither HOW MUCH of a trait is genetically determined

neither the extent to which an individual’s phenotype is due to genotype

• an estimate of contribution genetic vs environmental factors
• variation with in a certain population and an enviroment

Question 2

H^2 = VG/ VP….

-A high heritability means that most of the variation among individuals is caused by genetic variation among those individuals and not environmental variation.

Answer 2

broad sense HERITABILITY

H^2 = VG/ VP….Genetics over population

-zero broad sense indicates environment has the greatest influence on genetic factors

Question 3

h^2 = VA/ VP…

-A high heritability means that most of the variation among individuals is caused by genetic variation among those individuals and not environmental variation.

Answer 3

Narrow sense HERITABILITY

h^2 = VA/ VP… allele frequency over population

• due to additive genotypic variance alone
• zero narrow sense indicates environment has the greatest influence on genetic factors

Question 4

Narrow-sense heritability is due to what type of genetic variance?

Answer 4

• additive

- h^2 = VA/ VP… allele frequency over population

Question 5

multiple genes affecting a single trait that can be quantified like a pigment amount or level of intelligence ….can be termed

Answer 5

Polygenic (quantitative inheritance)

Question 6

multifactorial inheritance can be defined as…

Answer 6

polygenetic + enviromental factor (complex traits)

Question 7

the basis of continuous variation, additive alleles and multi gene hypothesis…

name 4…

Answer 7

1. continuous variation (quantified, counted)
2. polygenic (2 or more gene loci scattered through the genome
3. non additive alleles don’t contribute to the phenotype (contribution is small)
4. large number offspring needed to study polygenic traits
   - Narrow-sense heritability is due to additive alleles in poulation

Question 8

tumor suppressor genes or photo-oncogenes (promote cell division)…….

loss of function in both alleles, inactive/ active genes

Answer 8

tumor suppressor genes

-photo-oncogenes (promote cell division) - gain fx in one allele “always on” Ie: RAS regulation cell growth

Question 9

tumor suppressor genes; name three

Answer 9

1. RB1 - passes through G1/ S in presense to pRB protein

Question 10

DNA damage —–> _____________ —–> phoshorylation pRB protein and BCRA1

Answer 10

DNA damage —–> ACTIVATES KINASES—–> phoshorylation pRB protein and BCRA1

Question 11

what is the chromosomal theory of inheritance…

Answer 11

chromosomes contain genes in a linear order, homologous chromosomes seperate during meiosis , assorts independently

Question 12

List all 5 assumptions for Hardy-Weinberg

Answer 12

1. Random mating
2. Large populations
3. No natural selection
4. No migration
5. No change in mutation rate

Question 13

Consider following sample: AA(60), Aa (30), aa(10). What is the frequency of A? p=?
75

Answer 13

p=75

Question 14

The term to describe a pair of monozygotic twins where one is afflicted with osteoporosis and the other is not

Answer 14

Discordant