StemUp: AQA A level Biology 3.8.1 Alteration of the sequence of bases in DNA can alter the structure of proteins

What are gene mutations? (1)

Changes in the sequence of nucleotide bases in DNA

What are the 6 types of gene mutations? (6)

- Substitution

- Deletion

- Addition

- Duplication

- Translocation

- Inversion

What is a substitution gene mutation? (1)

The replacement of one or more bases by one or more different bases

What is a deletion gene mutation? (1)

The removal of one or more bases

What is an addition gene mutation? (1)

The adding of one or more bases

What is a duplication gene mutation? (1)

Where one or more bases is repeated

What is a translocation gene mutation? (2)

- Where a sequence of bases is moved from one location in the DNA molecule

- To another part of the genome

What is an inversion gene mutation? (1)

Where a sequence of bases is reversed

Why do some mutations cause a non-functional protein to be produced? (2)

- Results in frame shift - alteration in base triplets in point of mutation e.g. addition

- The sequence of amino acids is altered from the point of mutation and the protein formed is non-functional

Why do some base substitutions result in the same encoded amino acid? (2)

- Due to the degeneracy of the genetic code

- Which means the new base triplet will code ‎‏‏‎for the same amino acid

What are mutagenic agents used for? (2)

- To increase the rate of mutation

- E.g. benzene, X-rays etc