evolution

Question 1

what is the only new way alleles can be created?

Answer 1

mutations: permanent changes to a dna sequence

Question 2

how does dna mutations occur

define mutagens

Answer 2

• can be spontaneous: due to naturally occuring changes to dna
• can be induced: due to mutagens

mutagens: chemical/physical/bio agents that can induce changes in dna

Question 3

what are point mutations

name the substitution mutations

Answer 3

change to a single nucleotide
- silent
- missense
- nonsense

sub of a single nucleotide

Question 4

what is a silent mutation and the effect on the protein made?

Answer 4

• has no effect on protein sequence
  = still produces same amino acid

Question 5

what is a missense mutation and the effect on the protein made?

Answer 5

• productin of a codon that codes for a different amino acid
• affects primary structure (amino acid sequence)= changes 2nd and 3rd structure
  = affects function (non functional)

Question 6

what is a nonsense mutation and the effect on the protein made?

Answer 6

sub amino acid for a stop codon
- premature termination
= shorter polypeptide
- affects 2nd and 3rd structure
= non functional protein

Question 7

what is a framshift mutation and the effect on proteins produced?

Answer 7

addition or removal of a nucleotide
- changes every amino acid sequence downstream of point of mutation
= new protein (non functional)

Question 8

types of evidence to classify a species as extinct

2 marks

Answer 8

• no sightings or fossil remains
• no other evidence eg dna, feathers, nests, common food source present