Module 3 Flashcards

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1
Q

What are intra allelic effects?

A

The effect of an allele on a protein

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2
Q

What are inter allelic effects?

A

The affect of other genes influencing it

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3
Q

What is gene action?

A

From genotype to phenotype

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4
Q

What is the agouti gene?

A

Encodes to signal peptide for colour and lipid metabolism

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5
Q

Lethal gene example

A

The agouti gene

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6
Q

Are mutations of haplosufficient genes recessive or dominant?

A

Recessive

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7
Q

What is an allelic series?

A

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

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8
Q

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

A

Considered a mutant

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9
Q

What does an allelic series describe?

A

Dominance hierarchy of multiple alleles

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10
Q

What is the function of a null allele?

A

It does not have a function

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11
Q

What is hypomorphic allele function?

A

It has a partial function

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12
Q

What is incomplete dominance?

A

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

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13
Q

What is codominance?

A

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

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14
Q

What kind of relationships are codominance and incomplete dominance?

A

Non- Mendelian relationships

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15
Q

Incomplete dominance example in humans

A

Skin pigmentation

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16
Q

Codominance example in humans

A

ABO blood type

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17
Q

What kind of gene causes blood type in humans?

A

I gene

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18
Q

What is variable/incomplete penetrance?

A

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

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19
Q

Example of variable penetrance in humans

A

Retinoblastoma and polydactylyl

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20
Q

What is variable expressivity?

A

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

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21
Q

Examples of variable expressivity in humans

A

Marfan syndrome

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22
Q

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

A

Yes

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23
Q

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

A

Neurofibromatosis

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24
Q

What is pleiotropy?

A

One allele, affecting two or more phenotypes

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25
Q

What is polygenic inheritance?

A

Many genes and alleles, affecting the same phenotype

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26
Q

What are some qualitative phenotypes?

A

Height, skin colour, weight, intelligence, behavioural phenotypes

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27
Q

What are complementation tests?

A

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

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28
Q

What is allelism?

A

When mutations are alleles of same gene

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29
Q

What does complementation indicate?

A

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

30
Q

Are allelic mutations complementing or non-complementing?

A

Non-complementing

31
Q

Are non-allelic mutations complementing or non-complementing?

A

Complementing

32
Q

What are allelic mutations?

A

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

33
Q

What is a trans-heterozygote for allelic mutations?

A

Mutations in one gene

34
Q

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

A

Mutations in two genes

35
Q

What is a non-allelic mutation?

A

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

36
Q

What is molecular basis of genetic complementation?

A

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

37
Q

What are auxotrophs?

A

Mutants that need supplementation

38
Q

Are genes functionally isolated units?

A

No

39
Q

How are genes organized?

A

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

40
Q

What are suppressor mutations?

A

A mutations that reverts the phenotypic effects of an original mutation

41
Q

What is an enhancer mutation?

A

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

42
Q

What are the 3 levels of expressivity?

A

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

43
Q

What is allelic interactions?

A

Dominance, recessiveness, codominance, incomplete dominance

44
Q

What is gene interaction?

A

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

45
Q

What are gene interaction processes/examples?

A
  • additive gene action
  • complementary gene action
  • duplicate gene action
  • dominant epistasis
  • recessive epistasis
46
Q

What is the most obvious evidence of gene interaction?

A

The skewing of Mendelian ratios

47
Q

Additive gene action ratios

A

1 trait, 2 loci, 4 phenotypes

48
Q

Complementary gene action ratios

A

2 loci, 1 trait, 2 phenotypes

49
Q

Redundancy is also known as

A

Duplicate gene action

50
Q

Redundancy ratios

A

2 loci, 1 trait, 2 phenotypes

51
Q

Recessive epistasis ratios

A

2 loci, 1 trait, 3 phenotypes

52
Q

Dominant epistasis ratios

A

2 loci, 1 trait, 3 phenotypes

53
Q

What is additive gene action?

A

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

54
Q

Additive gene action expected ratio?

A

9:3:3:1

55
Q

What is complementary gene action?

A

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

56
Q

Complementary gene action phenotypic ratio

A

9:7

57
Q

What explains complementary gene action?

A

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

58
Q

What is redundancy?

A

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

59
Q

Redundancy modified phenotypic ratio

A

15:1

60
Q

What explains redundancy?

A

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

61
Q

What is a pseudoallele?

A

Duplicate genes, interact with each other’s alleles

62
Q

What is epistasis?

A

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

63
Q

What are the types of epistasis?

A

Recessive epistasis and dominant epistasis

64
Q

What is recessive epistasis?

A

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

65
Q

What is dominant epistasis?

A

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

66
Q

Recessive epistasis modified phenotypic ratio

A

9:3:4

67
Q

What is a model for recessive epistasis?

A

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

68
Q

Dominant epistasis modified phenotypic ratio

A

12:3:1

69
Q

What is a model for dominant epistasis?

A

Negative regulators of enzymatic activity, gene is chemical determiner

70
Q

What is pseudodominance?

A

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