mutations - PAPER TWO

Question 1

mutations occur…

Answer 1

• RANDOMLY
  a chromosome may not copy itself properly
  but some factors increase the risk eg
• exposure to ionising radiation
• chemicals called mutagens eg chemicals in tobacco/ carcinogens

Question 2

mutations increase the g……. v……..

Answer 2

genetic variation

Question 3

how do mutations change the genetic variation of a person?

Answer 3

• the sequence of the DNA bases code for a gene, so the gene is changed if the bases are changed

Question 4

what are the impacts of mutations? list the differences between low impact and high impact.

Answer 4

no effect on the phenotype: e.g. in an unimportant part of DNA
—-> most mutations have no impact on the phenotype
small impact: very slight variation for the organism - the change in amino acid only slightly impacts the protein formed
high impact - can be good or bad (e.g. bacteria resistance vs higher risk of cancer) because the protein coded for no longer carries out the same function

Question 5

enzymes can be impacted. why?

Answer 5

• enzymes are a type of protein
• proteins are coded for by the DNA bases in genes
• so a mutation could change its formation
• enzymes have very specific active site shapes to be able to bind to the substrate
• so any changes could mean the function changes or the enzyme stops being produced altogether

Question 6

an example of a mutation is…

Answer 6

antibiotic resistance