Mutation

Question 1

What is a mutation?

Answer 1

A heritable alteration in a gene or chromosome

Question 2

What are the three types of mutants?
Name a few

Answer 2

Exogenous
- ionising radiation
- mutagenic chemicals

Endogenous
- DNA replication defects
- transposable elements

Spontaneous events

Question 3

Not all mutations are damaging
Name two other types of effect

Answer 3

• Neutral
• Adaptive

Question 4

What does deamination mean?

Answer 4

Loss of an amino acid

Question 5

What does dimerisation mean?

Answer 5

Formation of a bond between two similar base pairs

Question 6

What are the two ends of mRNA?

Answer 6

5’ cap

PolyAtail

Question 7

What is an insertion mutation?

Answer 7

One or more nucleotides are added to a nucleic acid sequence (can be anywhere)

Question 8

What direction is DNA read in transcription?
Hence, what direction is mRNA synthesised?

Answer 8

3’ to 5’

5’ to 3’

Question 9

What direction is mRNA read in translation?

Answer 9

5’ to 3’

Question 10

What is a missense mutation?

Answer 10

A codon replaces one amino acid with another

Question 11

What is a nonsense mutation?

Answer 11

Changes a codon for an amino acid with a stop codon

Question 12

What is a frameshift mutation?

Answer 12

Nucleotides other than in multiples of three are added or removed from a nucleic acid sequence

Question 13

What is chromosomal inversion?

Answer 13

A stretch of chrome is inverted on the same chromosome

Question 14

What is chromosomal insertion?

Answer 14

A stretch of chromosome from one chromosome is inserted into another chromosome

Question 15

What is non invasive prenatal testing?

Answer 15

Method used to determine risk of the being born with certain chromosomal abnormalities

Tests analyse small DNA fragments in the blood of a pregnant woman

Question 16

What are synonymous mutations?

Answer 16

They are neutral - have no effect

Question 17

What type of mutation is sickle cell anaemia?
Name some symptoms

Answer 17

Autosomal recessive

Infections, weakness, sickle shaped RBC

Question 18

What is single nucleotide polymorphism?
What are they called when:
- have no effect
- outside gene
- inside gene

Answer 18

A change in a single base pair

Anonymous
Non-coding
Coding

Question 19

What are the four affects of SNP?

Answer 19

• the sequence of a gene
• the amount of a gene
• the polypeptide length
• no affect

Question 20

What are non-synonymous mutations?

Answer 20

They change the protein sequences

Question 21

What are the two types of DNA substitution?

Answer 21

Transition
Transversion

Question 22

Describe transition substitution

Answer 22

Change to the same type of base
(E.g. purine to purine)

Question 23

Describe transversion substitution

Answer 23

Change to different base type

Question 24

Which type of substitution is most likely to cause amino acid substitution?

Answer 24

Transversion

Question 25

For sickle cell anaemia:
Which codon is mutated?
What gene?
What type of mutation?

Answer 25

7

HBB

Missense base substitution (SNP)

Question 26

What causes Cri du Chat syndrome?

Answer 26

Deletion of short arm
Chromosome 5

Question 27

Name some symptoms of Cri du Chat

Answer 27

Low birth weight
Cardiac defects
Microcephaly - smallness of head
Epicanthal fold - skin fold of upper eyelid

Question 28

What chromosomes are affected in robertsonian translocation?

Answer 28

Acrocentric
13, 14, 15, 21 and 22