Mutations
Biology: AQA GCSE Higher, topic 6.1.14
Mutations
A mutation is a permanent change in the nucleotide sequence of DNA. Mutations happen continuously and normally only slightly affect proteins or don't affect them at all. Occasionally, a mutation may change the structure or shape of a protein. All genetic variants arise from mutations.
Undesirable change
- The outcome of a mutation is almost always detrimental to protein function.
- For example, in enzymes, the substrate may no longer be able to bind to the active site. In structural proteins, their strength may be reduced.
- Some regions of DNA do not encode protein sequences.
- The term given to these sections is non-coding DNA.
Survival advantage
- More rarely, a mutation may give a survival advantage, such as resistance to an antibiotic in bacteria.
- These mutations can be beneficial and represent the foundation of evolution by natural selection.
Test yourself on Mutations
How can a mutation affect the way an enzyme works?
Which of the following are correct about mutations?
What would most likely happen if a mutation occurred in a region of non-coding DNA?
A mutation changes the shape of a structural protein. What is the most likely effect on the protein?
What is the most likely effect of a new mutation on the protein it affects?