Key Area 6: Gene Mutations

Question 1

What is a mutation?

Answer 1

A mutation is a random change to an organism’s genetic material

Question 2

What is a gene mutation?

Answer 2

A gene mutation involves a random change in the sequence of bases within a single gene

Question 3

What are the three point mutations?

Answer 3

1) Substitution
2) Insertion
3) Deletion

Question 4

Describe substitution

Answer 4

Substitution involves one amino acid being swapped for another; this has a minor change to the overall protein

Question 5

Describe insertion

Answer 5

Insertion involves on amino acid being added to a protein; this has a major effect on the protein as everything after the change has been altered

Question 6

Describe deletion

Answer 6

Deletion involves one amino acid being removed from a protein; this has a major effect on the protein as everything after the change has been altered

Question 7

What is frameshift mutation?

Answer 7

Insertion and deletion are known as frameshift mutations as the entire protein after the change has been altered

Question 8

Describe types of mutation

Answer 8

• missense: after a substitution a new amino acid if coded for, code produced still makes sense but is not correct
• nonsense: after a substitution a stop codon is coded for, causes the protein to stop
• neutral: after a substitution a new amino acid is coded for with similar chemical properties, protein still functions and makes sense
• splice site: introns are usually removed but end up being left, makes a non-functional protein
• regulatory sequence: genes are incorrectly switched on or off resulting in proteins when not required or vice versa