Gene Mutations

Question 1

State the three types of gene mutations from section 4.

Answer 1

1. Deletion
2. Addition
3. Substitution

Question 2

Describe how duplication affects the DNA base sequence.

Answer 2

One or more bases are repeated (added) which cause the DNA base sequence to change causing the formation of a new protein

Question 3

How does inversion affect the DNA base sequence.

Answer 3

A sequence of bases is reversed which does not cause a frame shift so does not result in the formation of a new protein.

Question 4

How does translocation affect the DNA base sequence?

Answer 4

A sequence of bases is removed and relocated to a different place either on the same chromosome or on a different chromosome which causes a change in the DNA base sequence which leads to the formation of a new protein.

Question 5

What do mutations affect?

Answer 5

• DNA, mRNA and tRNA sequences
• amino acid sequence and protein structure
• function if proteins

Question 6

Describe the negative and positive effects of mutation.

Answer 6

Negative:
- mutations can have devastating effects which can result in genetic disorders

Positive:
- mutations can cause variation in populations which can sometimes cause an increased survival chance ( natural selection and evolution)

Question 7

Describe how hereditary mutations are passed down to offspring.

Answer 7

1. Mutation is present in the DNA of gametes
2. Offspring will inherit the mutations when gametes fuse during fertilisation
3. When a fertilised egg is divided by mitosis, all cells will all be genetically identical and therefore contain all the mutant DNA