Mutations Flashcards

1
Q

What is a mutation?

A

A heritable change to the DNA sequence of an organism

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2
Q

What is a wild-type allele?

A

The most prevalent allele in a population

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3
Q

What are 4 ways to classify mutations?

A

Where it came from, effects at a molecular level, effects on the phenotype, effects on gene product activity

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4
Q

Can mutations be spontaneous?

A

Yes, but they are rare because of proofreading mechanisms and repair find and fix most of them

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5
Q

What is a mutagen?

A

A substance that induces a mutation

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6
Q

What are the 3 classes of mutagens?

A

Chemical, physical, biological

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7
Q

What type of mutations are generated by chemical mutagens?

A

Point mutations

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8
Q

What are the 3 major mechanisms used by chemical mutagens to generate mutations?

A

Base modification, intercalating into the DNA backbone, base analogs

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9
Q

How does base modification create mutations?

A

Adding modifications to bases changes their H bonding properties, so they base pair with something else

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10
Q

What mechanism does EMS cause mutations through?

A

Base modification. Changes guanine to O-6-ethylguanine which base pairs with a T instead of C. Causes base pair substitutions

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11
Q

How does backbone intercalation create mutations?

A

Alters the physical structure of DNA and stalls replication, leading to the incorporation of incorrect bases

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12
Q

What mechanism do acridine and ethidium bromide cause mutations through?

A

Backbone intercalation. They are large, planar, multi-ringed molecules that in between the bases and disrupt the structure of DNA. Cause indels

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13
Q

How do base analogs create mutations?

A

They mimic normal bases and get incorporated during replication, but they base pair with the wrong thing

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14
Q

What mechanism does 5-bromouracil cause mutations through?

A

It mimics a thymine, so gets incorporated during DNA replication. The enol form will base pair with a G instead of an A

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15
Q

What types of mutations are generated by physical mutagens?

A

Large scale double strand breaks that result in deletions, inversions, or translocations. Pyrimidine dimers

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16
Q

What is ionizing radiation? What type of DNA damage and mutations does it cause?

A

Fast, high energy forms of radiation. Includes gamma rays, x-rays, fast neutrons. They create double strand breaks. Can result in deletions, inversions, or translocations

17
Q

What is non-ionizing radiation? What type of DNA damage and mutations does it cause?

A

Lower energy radiation that doesn’t cause strand breaks, aka UV light. Causes pyrimidine dimers

18
Q

What are the two types of deletions that could be caused by ionizing radiation? Which one is more common?

A

Terminal (end of the chromosome) and interstitial (inside a chromosome). Terminal is more common because it only requires one strand break

19
Q

What type of mutations are caused by biological mutagens?

A

Insertions and deletions

20
Q

What are transposons?

A

Moveable pieces of DNA that are endogenous to every eukaryotic genome

21
Q

What is an advantage to using transposons?

A

Cloning the affected gene is very easy, since we know the sequences of the transposon and use restriction enzymes to figure out where in the genome the mutation occurred

22
Q

How can transposons generate deletions?

A

If it is removed, it will take a bit of the surrounding DNA when it leaves and cause a small deletion

23
Q

What are the two mechanisms by which transposons generate mutations?

A

Replicative transposition and non-replicative transposition

24
Q

What is replicative transposition?

A

The original transposon gets copied, and the copy moves to a new location, but the original stays put and does not generate a deletion. Proceeds through an RNA intermediate (copy and paste)

25
Q

What is non-replicative transposition?

A

The original transposon gets cut out from where it was and gets moved to another location. Creates a deletion where it originally was