1.1. Mutations

Question 1

Mutations

Answer 1

Changes to the DNA sequence. They are almost always harmful because they interrupt the normal functioning of a protein.

Question 2

Addition mutations

Answer 2

Where one or more bases are added to the DNA sequence: e.g. ATCGTT -> ATCCGTT (a C is added)

Question 3

Deletion mutations

Answer 3

Where one or more bases are removed from the DNA sequence (e.g. ATCGTT -> ATCTT)

Question 4

Substitution mutations

Answer 4

Where one or more bases are changed from the middle of the DNA sequence (e.g. ATCGTT -> ACCGTT)

Question 5

Causes of mutation: DNA replication

Answer 5

• When DNA is replicated, the bases in the DNA sequence are read and copied.
• There can be errors in the replication process, which can cause mutations.
• Mutations are spontaneous.

Question 6

Causes of mutation: Mutagenic Agents

Answer 6

• These can increase the rate at which mutations occur.

- They include chemicals such as bromine and benzene and exposure to ionizing radiation and ultraviolet radiation.

Question 7

Causes of mutation: Chromosome mutations

Answer 7

• These can arise spontaneously during meiosis, and affect the number of chromosomes in a developing zygote.
• It is the production of haploid gametes.
• During meiosis, pairs of chromosomes are separated.
• Non-disjunction is when chromosome pairs do not separate properly.