Mutations
Biology: AQA A Level, topic 8.1.1
Types of Mutation
Mutations are changes in the base sequence of DNA. Mutations can be caused by errors in DNA replication. The different types of mutation are:
Addition
- Addition mutations are where one or more bases are added to the DNA sequence.
- E.g. ATCGTT → ATCCGTT
- In this example, a C is added in the middle of the DNA sequence.
Deletion
- Deletion mutations are where one or more bases are removed from the DNA sequence.
- E.g. ATCGTT → ATCTT
- In this example, the G is deleted from the middle of the DNA sequence.
Substitution
- Substitution mutations are where one or more bases are changed in the DNA sequence.
- E.g. ATCGTT → ACCGTT
- In this example, the first T is substituted for a C.
Inversion
- Inversion mutations are where the order of bases in the DNA sequence are inverted (reversed).
- E.g. ATCGTT → TTGCTA
- In this example, the order is reversed (i.e. the A moves from position 1 to position 6).
Duplication
- Duplication mutations are where one or more bases are duplicated (repeated) in the DNA sequence.
- E.g. ATCGTT → ATATCGTT
- In this example, the A and T found in positions 1 and 2 are duplicated.
Translocation
- Translocation mutations are where a section of the DNA sequence is moved to another section of the DNA sequence.
- Translocation can be within and across chromosomes.
Test yourself on Mutations
Which of the following mutations is a substitution mutation?
Which of these is a duplication mutation?
Which of the of the following statements about mutations are true?