(3.33-3.39) Variation + Mutations

What is variation?

differences between individuals within the same species

How can variations occur?

• random fertilisation

• environmental factors

• a combination

What is a mutation?

A rare, random change in genetic material

that can be inherited.

Why could a change in DNA impact the phenotype?

Often, mutations don’t impact the phenotype at all.

A mutation changes the structure of the sequence

rarely, this could change the sequence of amino acids enough that

it would change the protein formed

which could be impact the phenotype.

What factors could increase risk of mutation?

ionising radiation- gamma, x-ray, UV

chemical mutagens- like tar in tobacco

Explain Darwin’s theory of evolution by natural selection.

There is variation in a species.

Individuals with advantageous characteristics have a higher chance of survival.

They are therefore more likely to reproduce and pass on their advantageous alleles.

Over generations, the advantageous allele is more common in the population.

How can antibiotic resistance in bacteria grow?

random mutation = resistant allele

those with resistant allele survive + proliferate

passing on their resistant gene through plasmids

after some time = resistant strain that need different antibiotics

Why are resistant bacteria such a threat?

People don’t finish their treatment- increasing chance of resistant strains

Effective antibiotics are running out

Superbugs require special, limited antibiotics