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?

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
What is an antimorph?
The mutant gene product antagonizes the function of the WT gene product
26
What types of genes could possibly have an antimorphic allele?
Gene products that form a complex and are only functionally active in the complex
27
Are antimorphs a gain of function or a loss of function?
Loss of function
28
Are antimorphs dominant or recessive?
Dominant
29
What is pseudo-reversion?
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
What happens to the phenotype caused by an antimorph if we add more WT alleles?
The severity of the phenotype is reduced, because the gene products of the WT alleles swamp out the mutant ones
31
What is a neomorph?
The gene product has a novel function or activity
32
What sort of events often result in a neomorphic phenotype?
Ectopic expression - the gene product is doing its correct function at the wrong place or time
33
Are neomorphic mutations gain of function or loss of function
Gain of function
34
Are neomorphic mutations dominant or recessive?
Dominant
35
What happens to the phenotype of a neomorphic allele if we add more copies of the WT allele?
No change. We can't swamp out a neomorph