Mutations

Question 1

What is a mutation?

Answer 1

• A change in the DNA base sequence
• Happens spontaneuosly in cells

Question 2

What can increase the risk of a mutation?

Answer 2

• Carcinogens (released in cigarette smoke)
• Ionising radiiation

Question 3

How can a mutation effect an organism?

Answer 3

• A mutation would alter the base sequence meaning the sequence of amino acids that it codes for would be altered
• E.G: the active site of an ennzyme would change

Question 4

Do mutations always effect an organism?

Answer 4

• No, most of the time, a mutation doesn’t have a significant effect on the protein it codes for (it may look different but will still work the same)
• Most mustation occur in non-coding DNA (responsible for whether a gene is expressed or not)

Question 5

Explain substitution mutation

Answer 5

• One of the bases is changed for another
• 1 base changes : 1 codon changes : 1 amino acid changes : no significant effect on organism

Question 6

Explain insertion mutation

Answer 6

• An extra base is inserted inside the base sequence
• All subsequent codons change : all subsequent amino acids change
• Worse effect on organism then substitution

Question 7

Explain deletion mutation

Answer 7

• A random base is taken out (deleted) of the base sequence
• All subsequent codons change : all subsequent amino acids change
• Worse effect on organism then substitution