Module 3

Question 1

What are intra allelic effects?

Answer 1

The effect of an allele on a protein

Question 2

What are inter allelic effects?

Answer 2

The affect of other genes influencing it

Question 3

What is gene action?

Answer 3

From genotype to phenotype

Question 4

What is the agouti gene?

Answer 4

Encodes to signal peptide for colour and lipid metabolism

Question 5

Lethal gene example

Answer 5

The agouti gene

Question 6

Are mutations of haplosufficient genes recessive or dominant?

Answer 6

Recessive

Question 7

What is an allelic series?

Answer 7

Most common allele for a locus in nature arbitrarily referred to as wild-type, often dominant

Question 8

If an allele is not wild-type, what is it considered?

Answer 8

Considered a mutant

Question 9

What does an allelic series describe?

Answer 9

Dominance hierarchy of multiple alleles

Question 10

What is the function of a null allele?

Answer 10

It does not have a function

Question 11

What is hypomorphic allele function?

Answer 11

It has a partial function

Question 12

What is incomplete dominance?

Answer 12

Appearance of third phenotype that blends two parental ones, no clear dominance in heterozygote, blending

Question 13

What is codominance?

Answer 13

More than one allele is dominant, heterozygote displays both parental phenotypes, shows both

Question 14

What kind of relationships are codominance and incomplete dominance?

Answer 14

Non- Mendelian relationships

Question 15

Incomplete dominance example in humans

Answer 15

Skin pigmentation

Question 16

Codominance example in humans

Answer 16

ABO blood type

Question 17

What kind of gene causes blood type in humans?

Answer 17

I gene

Question 18

What is variable/incomplete penetrance?

Answer 18

The proportion of individuals of the same genotype that will either express determined phenotype or not express it at all, only some percentage of people show the trait

Question 19

Example of variable penetrance in humans

Answer 19

Retinoblastoma and polydactylyl

Question 20

What is variable expressivity?

Answer 20

Degree or intensity with which a genotype is expressed, all show the consequences but not to full extent just to a degree of severity

Question 21

Examples of variable expressivity in humans

Answer 21

Marfan syndrome

Question 22

Is it possible to have both variable penetrance and variable expressivity?

Answer 22

Yes

Question 23

What is an example of variable penetrance and variable expressivity in humans?

Answer 23

Neurofibromatosis

Question 24

What is pleiotropy?

Answer 24

One allele, affecting two or more phenotypes

Question 25

What is polygenic inheritance?

Answer 25

Many genes and alleles, affecting the same phenotype

Question 26

What are some qualitative phenotypes?

Answer 26

Height, skin colour, weight, intelligence, behavioural phenotypes

Question 27

What are complementation tests?

Answer 27

Based on that wild-type alleles will make up for mutated ones of a given gene

Question 28

What is allelism?

Answer 28

When mutations are alleles of same gene

Question 29

What does complementation indicate?

Answer 29

Non-allelic mutants - when more than one gene is responsible to same phenotype

Question 30

Are allelic mutations complementing or non-complementing?

Answer 30

Non-complementing

Question 31

Are non-allelic mutations complementing or non-complementing?

Answer 31

Complementing

Question 32

What are allelic mutations?

Answer 32

Where no functional gene 1 is synthesized in trans heterozygote; thus it will have mutant phenotype

Question 33

What is a trans-heterozygote for allelic mutations?

Answer 33

Mutations in one gene

Question 34

What is a trans-heterozygote for non-allelic mutations?

Answer 34

Mutations in two genes

Question 35

What is a non-allelic mutation?

Answer 35

functional products of both genes are synthesized in the trans heterozygote, wild-type phenotype

Question 36

What is molecular basis of genetic complementation?

Answer 36

Colour carried on different genes and can reappear, not dominant or recessive

Question 37

What are auxotrophs?

Answer 37

Mutants that need supplementation

Question 38

Are genes functionally isolated units?

Answer 38

No

Question 39

How are genes organized?

Answer 39

Genes are hierarchically organized to perform function (influence phenotype) and most phenotype are polygenic

Question 40

What are suppressor mutations?

Answer 40

A mutations that reverts the phenotypic effects of an original mutation

Question 41

What is an enhancer mutation?

Answer 41

A mutation in a gene that enhances the phenotype caused by a mutation in another gene

Question 42

What are the 3 levels of expressivity?

Answer 42

1) Allelic interaction (intra-genic) 2) Allele interaction with environment 3) Gene interaction

Question 43

What is allelic interactions?

Answer 43

Dominance, recessiveness, codominance, incomplete dominance

Question 44

What is gene interaction?

Answer 44

How alleles in different loci interact with one another to impact phenotype, reflects genetic organization in pathways controlling specific phenotypes

Question 45

What are gene interaction processes/examples?

Answer 45

- additive gene action - complementary gene action - duplicate gene action - dominant epistasis - recessive epistasis

Question 46

What is the most obvious evidence of gene interaction?

Answer 46

The skewing of Mendelian ratios

Question 47

Additive gene action ratios

Answer 47

1 trait, 2 loci, 4 phenotypes

Question 48

Complementary gene action ratios

Answer 48

2 loci, 1 trait, 2 phenotypes

Question 49

Redundancy is also known as

Answer 49

Duplicate gene action

Question 50

Redundancy ratios

Answer 50

2 loci, 1 trait, 2 phenotypes

Question 51

Recessive epistasis ratios

Answer 51

2 loci, 1 trait, 3 phenotypes

Question 52

Dominant epistasis ratios

Answer 52

2 loci, 1 trait, 3 phenotypes

Question 53

What is additive gene action?

Answer 53

Alleles of both genes influence the same phenotype , F1 has different phenotype than parentals

Question 54

Additive gene action expected ratio?

Answer 54

9:3:3:1

Question 55

What is complementary gene action?

Answer 55

Genes acting in the same pathway, homozygous for either mutation, identical mutant phenotype

Question 56

Complementary gene action phenotypic ratio

Answer 56

9:7

Question 57

What explains complementary gene action?

Answer 57

Genes have the same linear pathway - downstream gene function fully depend on function of upstream gene

Question 58

What is redundancy?

Answer 58

Dominant alleles of both genes overpowers each other's recessive alleles

Question 59

Redundancy modified phenotypic ratio

Answer 59

15:1

Question 60

What explains redundancy?

Answer 60

Parallel function of genes on pathway - overlapping roles for two genes which independently make up for absence of function of other

Question 61

What is a pseudoallele?

Answer 61

Duplicate genes, interact with each other's alleles

Question 62

What is epistasis?

Answer 62

Alleles of one locus are suppresses by alleles of a different locus in a given phenotype

Question 63

What are the types of epistasis?

Answer 63

Recessive epistasis and dominant epistasis

Question 64

What is recessive epistasis?

Answer 64

When recessive allele of one gene masks effect of either allele of second gene

Question 65

What is dominant epistasis?

Answer 65

When dominant allele of one gene masks effect of either allele of second gene

Question 66

Recessive epistasis modified phenotypic ratio

Answer 66

9:3:4

Question 67

What is a model for recessive epistasis?

Answer 67

Genes in pathway where accumulation of intermediate products are associated with alternative phenotypes

Question 68

Dominant epistasis modified phenotypic ratio

Answer 68

12:3:1

Question 69

What is a model for dominant epistasis?

Answer 69

Negative regulators of enzymatic activity, gene is chemical determiner

Question 70

What is pseudodominance?

Answer 70

The sudden appearance of a recessive phenotype in a pedigree, due to the deletion of a masking dominant gene