Lecture 16 - Causes of DNA mutation Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

What is a mutation?

A

An alteration in the nucleotide sequence of a DNA molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the two ways mutations can occru?

A

Errors in DNA replication, spontaneous mutation
Mutagens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a mutagen?

A

Chemical or environmental agents that cause changes in DNA molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does an error in replication result in a mutation?

A

If one base is replicated incorrectly, when the next replication occurs the complementary base to this incorrect base will be different also
This increases the scale of the mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the cause of errors in DNA replication or spontaneous mutations?

A

Mistakes being made by DNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a tautomer?

A

An isomer with a slightly different chemical structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is base tautomerism?

A

DNA polymerase is tricked due to tautomers
It can’t tell the difference between two isomers and instead may place the incorrect one in
This causes tautomeric shift and the wrong amino acid is used

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the two ways that mutagens can cause mutations?

A

Base analogs
Direct structural change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is meant by base analogs?

A

Chemicals that look like bases are incorporated instead of bases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is an example of a base analog causing a mutation?

A

5bU is an analog of thymine and may be placed into sequence
Usually this is no problem
However there is an enol tautomer of 5bU that pairs with G which can cause tautomeric shift

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is direct structural change?

A

Deaminating agents change the structure of some nucleotides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are some effects of deaminating agents?

A

Deamination of adenine gives hypoxanthine which pairs with C not T
Deamination of cytosine gives uracil, which pairs with A not G
Deamination of guanine gives xanthine which blocks DNA replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are some other agents that cause structural changes to nucleotides?

A

Alkylating agents which add alkyl groups
Intercalating agents which insert between base pairs
Ultraviolet radiation which causes base dimerisation
Heat which causes detachment of bases and gives rise to an AP site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q
A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly