Mutations

Question 1

What is a mutation?

Answer 1

a change in the sequence of bases in DNA

Question 2

What is disrupted by mutations?

Answer 2

protein synthis

Question 3

What are the types of mutation?

Answer 3

substituion

deletion

or insertion

(of one or more nucleotide or base pairs within a gene)

Question 4

WHat is a point mutation

Answer 4

if only one nucleotide is affected

Question 5

What is substitution? What occurs because of it?

Answer 5

• substitution of a single nucleotide changes the codon in which it occurs
• if the new codon coes for a different amino acid this will lead to a change in the primary structure of the protein

Question 6

What effect does the degenerate nature of genetic code have on mutation?

Answer 6

the new codon still codes for the same amino acid leading to no change in the protein synthesised

Question 7

What will determine the impact of the new amino acid on the protein?

Answer 7

postion and involvemnt of the amino acid in R group interactions

Question 8

What does insertion or deletion of a nucleotide, or nucleotides lead to?

Answer 8

• frameshift mutation
• the triplet code means that sequences of bases are transcribed consecutively in non-overlapping groups of three
• this is the reading frame of bases
• each group of three bases corresponds to one amino acid
• the addition or deletion of a nucleotide moves, or shifts, the reading frame of the sequence of bases
• this will change every successive codon from the point of the mutation

Question 9

When does insertion or deletion not have a profound effect?

Answer 9

• the number of nucleotides changed is a multiple of three
• multiples of three correspond to full codons and therefore the reading frame will not be changed
• but the protein formed will still be affected as a new amino acid is added