Gene Mutations Flashcards

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1
Q

How do mutations drive evolution?

A

They give rise to genetic diversity.

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2
Q

What are polymorphisms?

A

Multiple Wt alleles for one gene.

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3
Q

What is a forward mutation?

A

Change from Wt to mutant.

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4
Q

What is a reverse mutation or reversion?

A

Change from mutant to Wt

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5
Q

Are mutations random or adaptive?

A

Random

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6
Q

In the experiment conducted by Luria and Delbruck, what results would suggest that mutations are adaptive?

A

In generations exposed to the toxin, the number of colonies resistant is constant between cultures.

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7
Q

In the experiment conducted by Luria and Delbruck, what results would suggest that mutations are random?

A

In generations exposed to the toxin, the number of colonies resistant varies greatly between cultures.

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8
Q

What are prototrophs?

A

Wt bacterial strains that can grow on minimal media

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9
Q

What are auxotrophs?

A

Mutants that cannot synthesise own amino acids.

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10
Q

What is the effect of mutations in promotor or regulatory elements?

A

Increase or decrease in transcription.

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11
Q

What is the effect of mutations in the 5’ or 3’ end?

A

Altered ability of mRNA translation and/or stability

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12
Q

What is the effect of mutations in the splice site?

A

pre-mRNA may not be spliced correctly, resulting in a frame-shift mutation.

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13
Q

Which mutations can be passed on to offspring- somatic or germ line?

A

Germ line.

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14
Q

What are conditional mutations?

A

Mutations that affect a phenotype only under specific condition. E.g. fly mutants- temperature.

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15
Q

In which two cases are loss-of-function alleles dominant?

A

Haploinsufficiency and dominant-negative.

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16
Q

What is haploinsufficiency?

A

One allele is mutated while the other is not and 50% is not sufficient. Heterozygote will have an altered phenotype.

17
Q

What is the dominant-negative occurrence?

A

The mutant protein is not functional and interferes with the function of the normal protein in heterozygotes.

18
Q

Which proteins are usually affected by the negative-dominant occurrence?

A

Structural proteins which form dimers or multimers.

19
Q

List three effects of gain-of function mutations.

A

New function, always active (constitutive), mutant gene expressed and increased levels or in different areas.