Genetics: Genetic Diversity - Mutations

Question 1

What is a gene mutation?

Answer 1

• Gene mutations involve a change in the DNA base sequence of chromosomes

Question 2

What type of errors can occur due to gene mutations?

Answer 2

• Substitution

- Deletion

Question 3

What is substitution?

Answer 3

• When one base is substituted with another

Question 4

What is deletion?

Answer 4

• When one base is deleted

Question 5

What effects do changes in DNA bases result in?

Answer 5

• Order of DNA bases determines the type and order of amino acids produced
• Mutations can change sequence of amino acids it codes and could affect protein formed

Question 6

What are the effects of substitution mutations?

Answer 6

• Degenerate nature of genetic code means some amino acids are coded for by more than one DNA triplet
• Substitution mutations don’t always result in a change to amino acid sequence of the protein

Question 7

What are the effects of deletion mutations?

Answer 7

• Deletions always result in a change in amino acid sequence of protein
• Changes number of bases present, causing a frame shift
• Means every amino acid after deletion will be affected

Question 8

How do mutations occur?

Answer 8

• Mutations can occur spontaneously and are random

- Can occur when DNA is misread during replication

Question 9

What can increase the rate of mutation?

Answer 9

• Mutagenic agents

- Increase probability of a mutation occurring

Question 10

Give examples of mutagenic agents

Answer 10

• UV radiation
• Ionising radiation
• Gamma rays
• X-rays

• Chemicals
- Tar in cigarette smoke

• Some viruses