DNA - Mutations

Question 0

What is a point mutation?

Answer 0

• it is when one base pair replaces another

Question 1

What is a mutation?

Answer 1

• it is a change in the amount of, or arrangement of genetic material in a cell
• they cause changes to the sequence of nucleotides in a DNA molecule

Question 2

What does a nonsense point mutation do?

Answer 2

It changes the bases to that a stop codon is introduced, the polypeptide is truncated

Question 3

What does a missence point mutation do?

Answer 3

It changes a base so that it codes for a different amino acid, primary structure is altered

Question 4

What does a silent point mutation do?

Answer 4

It changes a base but still codes for the same amino acid

Question 5

What is an insertion/deletion mutation?

Answer 5

It is when one or more nucleotide pairs are inserted or deleted from s length of DNA, these cause a frameshift

Question 6

What does a frameshift do?

Answer 6

It alters the reading frame of the gene downstream of the mutation, so after the mutation it will cause a different sequence of amino acids to be coded for

Question 7

Why can a mutation effect the way that a protein functions?

Answer 7

• a mutation can change the amino acid that is coded for or truncate the polypeptide
• this could change the R group on the amino acid
• this could then affect/change the bonding in the secondary or tertiary structure
• this could then change/alter the the 3D shape and so change the function of the protein

Question 8

What effect could an insertion/deletion have on the structure of a protein?

Answer 8

• more of an effect than a point mutation as all the amino acids after the mutation will change
• this means that bonding between R groups will change which could change the 3D shape of the protein as the tertiary and secondary structure will be different

Question 9

Explain how a mutation can have neutral effects

Answer 9

• a mutation can have neutral effects if it changes a base in a triplet but the amino acid that the triplet codes for doesn’t change
• if the mutated triplet changes the amino acid but has no effect on the function of the protein
• if the mutation occurs in non-coding parts of the DNA

Question 10

Explain how a mutation could have a beneficial effect

Answer 10

• could have an advantageous effect on an organism e.g. Increase its chances of survival

Question 11

Explain how a mutation could have harmful effects

Answer 11

• could have a disadvantageous effect on an organism e.g. decrease its chances of survival