8.1.1

Mutations

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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:

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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.
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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.
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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.
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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).
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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.
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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.

Jump to other topics

1Biological Molecules

2Cells

3Substance Exchange

4Genetic Information & Variation

5Energy Transfers (A2 only)

6Responding to Change (A2 only)

7Genetics & Ecosystems (A2 only)

8The Control of Gene Expression (A2 only)

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