Unit 1 - Mutations Key Area 4

Question 1

What is a mutation

Answer 1

A mutation is a change in the DNA that can result in no protein or an altered protein being synthesised.

Question 2

What increases mutations

Answer 2

Mutations can be increased by mutagenic agents (e.g. mustard gas) and various types of radiation (X-Rays, UV light, Gamma Rays)

Question 3

What does a single gene mutation involve and whats the result

Answer 3

Single gene mutations involve the
alteration of a DNA nucleotide sequence as a
result of the substitution, insertion or deletion
of nucleotides.

Question 4

What is missense
What can it result in
Give an example

Answer 4

Missense mutations result in one amino acid
being changed for another.
This may result in a non-functional protein or have little effect on the protein.
Example: Sickle-cell disease, PKU

Question 5

What is nonsense
What can it result in
Give an example

Answer 5

Nonsense is replacing an amino acid codon with a premature stop codon
This results in the protein being shorter than normal
Example: Duchenne muscular dystrophy (DMD)

Question 6

What is Splice- Site
What can it result in
Give an example

Answer 6

Splice-site mutations result in some introns being retained and/or some exons not being included in the mature transcript.
Example: Beta Thalassemia

Question 7

What type of single gene mutations results in a frame shift mutation

Answer 7

Nucleotide insertions or deletions result in frame shift mutation.

Question 8

What is a frame shift mutation and how does it affect the protein produced

Answer 8

Frame-shift mutations cause all of the codons and all of the amino acids after the mutation to be changed.
This has a major effect on the structure of the protein produced.

Question 9

What does chromosome mutation involve

Answer 9

Chromosome mutations involve such a substantial change to the chromosomes structure that the mutation is often lethal

Question 10

Name the different types of chromosome mutation

Answer 10

1) Duplication
2) Deletion
3) Inversion
4) Translocation

Question 11

Describe the chromosome mutation Duplication

Answer 11

Duplication is where a section of a
chromosome is added from its homologous
partner.

Question 12

Describe the chromosome mutation Deletion

Answer 12

Section of chromosome is deleted/ removed. This results in a shorter chromosome.

Question 13

Describe the chromosome mutation Translocation

Answer 13

Translocation is where a section of a
chromosome is added to a chromosome, not
its homologous partner.

Question 14

Describe the chromosome mutation Inversion

Answer 14

Section of chromosome is reversed.

Question 15

What are nucleotide substitutions

Answer 15

Nucleotide substitutions — missense,

nonsense and splice-site mutations.