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 re-join in the reverse order i.e. they have flipped

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, meaning the entire amino acid sequence produced will be different

Question 8

Which mutations are most likely to have a smaller 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 change to the amino acid sequence always harmful?

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?

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