4: GENETICS - MUTATIONS

Question 1

What is a gene mutation?

Answer 1

a mutation that involves a change in the DNA base sequence of chromosomes

Question 2

What are 2 types of gene mutations that can occur?

Answer 2

• deletion
• substitution

Question 3

What effect does deletion of a base have on the sequence of amino acids and the polypeptide formed?

Answer 3

• base is deleted so no. of bases changes causing a shift in the base triplets after the point where the base was deleted
• this means there is a change in the sequence of amino acids
• H bonds, ionic bonds and disulfide bridges
• therefore the tertiary structure of the protein is altered
• this means that the protein produced will be non-functional

Question 4

What are the 2 possible effects that the substitution of a base could have on the sequence of amino acids and the polypeptide formed?

Answer 4

• could result in a different sequence of amino acids, which would produce a non-functional protein
• however the substitution could have no effect on the sequence of amino acids as the genetic code is degenerate meaning more than 1 codon can code for a specific amino acid