Unit 1 (K4) - Mutations

Question 1

What is a mutation?

Answer 1

Mutations are random abnormal changes in the DNA

Question 2

What factors increase the rate of mutations?

Answer 2

1. Radiation (UV light, X-rays)
2. Mutagenic agents (mustard gas, smoking etc)

Question 3

What are single gene mutations?

Answer 3

This involves the alteration of a DNA nucleotide sequence as a result of the substitution, insertion, or deletion of nucleotides.

Question 4

What do substitution mutations include?

Answer 4

1. Missense
2. Nonsense
3. Splice-site mutations

Question 5

What is a missense mutation?

Answer 5

A missense mutation is where one amino acid has been changed for another, this may result in a non-functional protein or have little effect. An example of a missense mutation is sickle cell disease.

Question 6

What is a nonsense mutation?

Answer 6

A nonsense mutation is where a premature stop codon has been introduced, resulting in a shorter protein. An example of a nonsense mutation is DMD.

Question 7

What is a splice-site mutation?

Answer 7

A splice site mutation is where some introns have been retained and some exons removed in the mature mRNA transcript.

Question 8

What are frame-shift mutations?

Answer 8

Frame-shift mutations are more harmful than substitutions as they result in all the amino acids/codons to be changed after the mutation. This is likely to result in a non-functional protein. Frame-shift mutations include deletion and insertion.

Question 9

What is a deletion mutation?

Answer 9

A deletion mutation is where a nucleotide has been removed.

Question 10

What is an insertion mutation?

Answer 10

An insertion is where a nucleotide has been added.

Question 11

What is an example of a frame-shift mutation?

Answer 11

Cystic Fibrosis.

Question 12

What are chromosome structure mutations?

Answer 12

Chromosome structure mutations involve the substantial change to chromosomes structure. This allows the alteration of several functional genes. The substantial change means they are more harmful than single gene mutations and can be lethal.

Question 13

What are the types of chromosome structure mutations?

Answer 13

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

Question 14

What is a deletion structure mutation?

Answer 14

A deletion structure mutation includes a section of a chromosome to be REMOVED.

Question 15

What is a translocation structure mutation?

Answer 15

A translocation mutation is where a section of a chromosome has been added, NOT from its homologous partner

Question 16

What is a duplication structure mutation?

Answer 16

A duplication mutation is where a section of a chromosome has been ADDED, FROM its homologous partner.

Question 17

What is an inversion structure mutation?

Answer 17

An inversion mutation is where a section of a chromosome has been REVERSED.