Muller's morphs Flashcards

1
Q

How are mutations classified in Muller’s morphs?

A

Based on the effect on gene product function or activity

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2
Q

What is a compound heterozygote?

A

A individual who has two different mutant alleles of a gene

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3
Q

What is the Df allele?

A

Deficient. The gene is deleted

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4
Q

What are the 5 Muller’s morphs?

A

Amorph, hypomorph, hypermorph, antimorph, and neomorph

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5
Q

How much gene product activity is seen in an amorph (compared to WT) when:

a) WT/m
b) m/m
c) m/Df

A

a) Same as the WT if the null allele is recessive. No function if it is dominant
b) No function
c) No function

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6
Q

How much gene product activity is seen in a hypomorph (compared to WT) when:

a) WT/m
b) m/m
c) m/Df

A

a) Same as WT if recessive, less than WT if dominant
b) Less than WT
c) Way less than WT, but still has a bit of function

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7
Q

How much gene product activity is seen in a hypermorph (compared to WT) when:

a) WT/m
b) m/m
c) m/Df

A

a) More than WT
b) A lot more than WT
c) less than with 2 copies of the mutant allele, might be close to the WT phenotype

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8
Q

What is a amorphic allele?

A

An allele that encodes a gene product with no function

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9
Q

Are amorphic mutations a gain of function or a loss of function?

A

Loss of function

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10
Q

Are amorphic mutations dominant or recessive?

A

Usually recessive, but sometimes dominant

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11
Q

What is a hypomorphic allele?

A

An allele whose gene product still has some function, but less function than the WT gene product

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12
Q

Are hypomorphic mutations a gain of function or a loss of function?

A

Loss of function

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13
Q

Are hypomorphic mutations dominant or recessive?

A

Usually recessive, but sometimes dominant

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14
Q

How can we tell an amorph and a hypomorph apart?

A

Homozygous mutant and deficient will have the same phenotype if it is an amorph. They will be different if it’s a hypomorph, which the deficient being more severe

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15
Q

What happens to the phenotype if more copies of an amophic allele are added?

A

Nothing. The alleles have no function

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16
Q

What happens to the phenotype if more copies of a hypomorphic allele are added?

A

The severity of the phenotype is reduced. Can get back to WT with enough copies

17
Q

What is an allelic sequence?

A

Null alleles and hypomorphic alleles of a gene are arranged from the most to least severe phenotypes

18
Q

What types of mutations could result in a hypomorphic allele?

A

Mutations in the 5’ UTR that reduce ribosome binding, missense mutations

19
Q

What is a hypermorphic allele?

A

The mutation either enhances gene product function or makes more copies be produced

20
Q

Are hypermorphs a gain of function or a loss of function?

A

Gain of function

21
Q

Are hypermorphs dominant or recessive?

A

Dominant

22
Q

Why can a hypermorphic mutation be lethal in the homozygous state?

A

The excess of the gene product will poison the cell and it results in the death of the embryo

23
Q

What is the defining feature of a hypermorphic allele?

A

The deficient mutant has a less severe phenotype than homozygous mutant

24
Q

What are some mutations could result in a hypermorphic allele?

A

Promotor or enhancer mutations that result in better RNA polymerase binding, which results in more transcription

25
Q

What is an antimorph?

A

The mutant gene product antagonizes the function of the WT gene product

26
Q

What types of genes could possibly have an antimorphic allele?

A

Gene products that form a complex and are only functionally active in the complex

27
Q

Are antimorphs a gain of function or a loss of function?

A

Loss of function

28
Q

Are antimorphs dominant or recessive?

A

Dominant

29
Q

What is pseudo-reversion?

A

The introduction of a null mutation into an antimorphic allele, which knocks it out so it stops antagonizing the WT product. Either restores the WT phenotype or it becomes a hypomorph

30
Q

What happens to the phenotype caused by an antimorph if we add more WT alleles?

A

The severity of the phenotype is reduced, because the gene products of the WT alleles swamp out the mutant ones

31
Q

What is a neomorph?

A

The gene product has a novel function or activity

32
Q

What sort of events often result in a neomorphic phenotype?

A

Ectopic expression - the gene product is doing its correct function at the wrong place or time

33
Q

Are neomorphic mutations gain of function or loss of function

A

Gain of function

34
Q

Are neomorphic mutations dominant or recessive?

A

Dominant

35
Q

What happens to the phenotype of a neomorphic allele if we add more copies of the WT allele?

A

No change. We can’t swamp out a neomorph