3.8.1 DNA and the Structure of Proteins

Question 1

What is a mutation

Answer 1

An alteration to the DNA base sequence
Often arise spontaneously during DNA replication

Question 2

What are addition and deletion mutations

Answer 2

Where one or more nucleotides (bases) are either inserted or deleted from the DNA sequence

Question 3

What is a substitution mutation

Answer 3

Where one nucleotide (base) in the DNA sequence is replaced by another

Question 4

What is a duplication mutation

Answer 4

Where one or more nucleotides (bases) duplicate and repeat

Question 5

What is an inversion mutation

Answer 5

Where a group of nucleotides (bases) become separated from the DNA sequence, then rejoin in the reverse order

Question 6

What is a translocation mutation

Answer 6

Where a group of nucleotides (bases) become separated from the DNA sequence, and are then inserted into the DNA of a different chromosome

Question 7

Which mutations are most likely to have a significant impact and why

Answer 7

Insertion, deletion, duplication, translocation
Because they produce a frameshift, the entire amino acid sequence produced will be different

Question 8

Which mutations are less likely to have a significant impact and why

Answer 8

Substitution, inversion
Because they only alter one or very few triplets, the amino acid sequence might not be affected due to the degenerate nature of the genetic code

Question 9

Is a mutation resulting in a chance to the amino acid sequence always harmfu;

Answer 9

No; may be neutral if the resulting change in protein has no effect on the organism
Also may be beneficial, which is the basis for evolution and natural selection

Question 10

What is a mutagenic agent
Give examples

Answer 10

Factors that increase the rate of gene mutation
Chemical mutagens such as alcohol and benzene
Ionising radiation such as UV and x-ray