Mutations

Mutation = RANDOM CHANGE to genetic material.

Chromosome mutation = Change to number or STRUCTURE of chromosomes. 

Substances causing mutations:

• Tar,
• Gamma rays,
• UV light,
• X-rays.

Classes of mutations:

POINT mutation/SUBSTITUTION - One base pair replaces another.

INSERTION/DELETION - Causes frameshift.

3 types of point mutations: 

• Nonsense,
• Misense,
• Silent.

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.

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. 

Neutral mutations:

• 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. 

Harmful mutations:

• Paler skin = Burned, skin cancer.
• Sunlight not intense enough to produce sufficient vitamin D in darker skinned.

Beneficial mutations:

• Melanin in darker skinned protects from harmful UV light.
• Paler skin = Produces more vitamin D.