Examples and classes of mutations
Mutation = RANDOM CHANGE to genetic material.
Chromosome mutation = Change to number or STRUCTURE of chromosomes.
Substances causing mutations:
- Gamma rays,
- UV light,
Classes of mutations:
POINT mutation/SUBSTITUTION - One base pair replaces another.
INSERTION/DELETION - Causes frameshift.
Effects of substitutions, insertions and deletions
3 types of point mutations:
Nonsense and misense: Causes different amino acid to be produced.
Therefore chain is affected. Nonsense codes for STOP.
Silent: Same amino acid is produced.
Therefore chain is unaffected.
Insertion/deletion: Causes frameshift.
All affected from mutation onwards.
Causes different 3D structure.
Beneficial, neutral and harmful mutations
If the insertion/deletion was closer to the start of the chain, it would have a larger effect as it would cause more amino acids to be changed.
- Neither beneficial or harmful effect.
- Produces no change if mutation is in non-coding region of DNA.
- It is a silent mutation.
- E.g. ability to roll tongue,free/attached ears.
- Paler skin = Burned, skin cancer.
- Sunlight not intense enough to produce sufficient vitamin D in darker skinned.
- Melanin in darker skinned protects from harmful UV light.
- Paler skin = Produces more vitamin D.