1.6 mutations

Question 1

what is a mutation?

Answer 1

• changes in the structure and amount of an organisms DNA
• that can result in no protein or an altered protein being synthesised.
• They are spontaneous and random. .

Question 2

Name the four types of single-gene mutation

Answer 2

• deletion
• insertion
• substitution

Question 3

what is the impact of a deletion mutation on the amino acid sequence?

Answer 3

• one base is deleted resulting in a shift in “reading frame”
• all of the codons and all of the amino acids after the mutation to be changed.
• This has a major effect on the structure of the protein produced

Question 4

What is the impact of an insertion mutation on the amino acid sequence

Answer 4

• one base is inserted resulting in a shift in “reading frame”
• all codons amino acids after the mutation are changed.
• major effect on the structure of the protein produced - frame-shift

Question 5

what are the possible results of nucleotide substitutions?

Answer 5

• missense
• nonsense
• spice-site mutations

Question 6

What do missense mutations result in and what are their effect on the protein?

Answer 6

• one amino acid being changed for another

- may result in a non-functional protein or have little effect on the protein

Question 7

what do nonsense mutations result in and what is it’s effect on the protein structure?

Answer 7

• premature stop codon being produced

- results in a shorter protein

Question 8

what do frame-shift mutations result in?

Answer 8

• due to nucleotide insertions or deletions
• all of the codons and all of the amino acids after the mutation are changed
• has a major effect on the structure of the protein produced

Question 9

what do splice-site mutations result in?

Answer 9

• an intron being retained and/or an exon not being included in the mature transcript
• results in an altered protein which would not function normally

Question 10

name the 4 chromosome structure mutations

Answer 10

• duplication
• deletion
• inversion
• translocation

Question 11

What is a duplication mutation?

Answer 11

a section of chromosome is added from its homologous partner, leading to repeated genes

Question 12

what is a deletion (chromosome structure) mutation?

Answer 12

a section of a chromosome is removed

Question 13

what is an inversion mutation?

Answer 13

a section of chromosome is reversed

Question 14

what is a translocation mutation?

Answer 14

a section of chromosome is added to a chromosome that is not its homologous partner

Question 15

What is the effect of chromosome mutations?

Answer 15

the substantial changes in chromosome mutations often make them lethal

Question 16

what is the role of duplication mutations in evolution?

Answer 16

• Duplication allows potential beneficial mutations to occur
• in a duplicated gene whilst the original gene can still be expressed
• to produce its protein.

Question 17

What do single gene mutations involve?

Answer 17

the alteration of a DNA nucleotide sequence as a result of the substitution, insertion or deletion of nucleotides

Question 18

what is the impact of a substitution mutation on the amino acid sequence?

Answer 18

• missense-one amino acid changed
• nonsense-major impact on protein structure
• splice site mutation-introns retained and/or exons not being included in the mature transcript

Question 19

what is the significance of gene mutation in evolution?

Answer 19

-mutation provides the only source of new variation for living organisms and so has a vital importance in evolution