1.6 mutations Flashcards

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1
Q

what is a mutation?

A
  • 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. .
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2
Q

Name the four types of single-gene mutation

A
  • deletion
  • insertion
  • substitution
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3
Q

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

A
  • 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
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4
Q

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

A
  • 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
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5
Q

what are the possible results of nucleotide substitutions?

A
  • missense
  • nonsense
  • spice-site mutations
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6
Q

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

A
  • one amino acid being changed for another

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

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7
Q

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

A
  • premature stop codon being produced

- results in a shorter protein

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8
Q

what do frame-shift mutations result in?

A
  • 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
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9
Q

what do splice-site mutations result in?

A
  • 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
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10
Q

name the 4 chromosome structure mutations

A
  • duplication
  • deletion
  • inversion
  • translocation
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11
Q

What is a duplication mutation?

A

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

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12
Q

what is a deletion (chromosome structure) mutation?

A

a section of a chromosome is removed

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13
Q

what is an inversion mutation?

A

a section of chromosome is reversed

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14
Q

what is a translocation mutation?

A

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

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15
Q

What is the effect of chromosome mutations?

A

the substantial changes in chromosome mutations often make them lethal

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16
Q

what is the role of duplication mutations in evolution?

A
  • Duplication allows potential beneficial mutations to occur
  • in a duplicated gene whilst the original gene can still be expressed
  • to produce its protein.
17
Q

What do single gene mutations involve?

A

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

18
Q

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

A
  • 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
19
Q

what is the significance of gene mutation in evolution?

A

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