19.1 mutations and variation Flashcards

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1
Q

what is a mutation?

A

change in the sequence of bases in DNA

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2
Q

how is protein synthesis affected by a mutation?

A

the wrong bases and transcribed which means that translation would lead to the wrong amino acids being produced and thus a different primary structure of a protein

so the final 3D structure may change

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3
Q

what are the three types of mutation?

A

substitution
deletion
insertion

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4
Q

what is a substitution mutation?

A

when a nucleotide is substituted for another which leads to a different codon

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5
Q

when can a substitution mutation lead to no change?

A

when the codon replacing the original codon codes for the same amino acid and so the same protein is produced

DEGENERATE NATURE OF GC

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6
Q

what is a deletion mutation?

A

when one or more nucleotides are removed

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7
Q

what is an insertion mutation?

A

when one or more nucleotides are added

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8
Q

what does insertion and deletion lead to?

A

a frameshift mutation

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9
Q

what is a frameshift mutation?

A

by adding or removing a nucleotide, you displace the following codons which, due to the non-overlapping nature of the GC, changes every successive codon

so changes the base sequence

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10
Q

what are the 3 effects of a mutation?

A

no effect
damaging
beneficial

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11
Q

no effect

A

mutation causes no effect on the phenotype of an organism

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12
Q

damaging

A

mutation causes major change to an organism’s phenotype which prevents essential processes

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13
Q

beneficial

A

mutation causes a change to an organism’s phenotype which provides an advantageous characteristic

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14
Q

when can a mutation have no effect?

A

mutation changes a base in a codon but the codon stays the same so the same amino acid is translated

mutation changes a base in a codon and a different amino acid is translated BUT the new amino acid is chemically similar to the original so functions very similarly

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15
Q

how do mutations occur?

A

spontaneously during DNA replication

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16
Q

what is a mutagen?

A

an agent which causes mutations

increases the rate of mutations

17
Q

what is depurination?

A

the loss of a purine base

18
Q

what is depyrimidination?

A

the loss of a pyramidine bae

19
Q

what do depurination and depyrimidination cause?

A

leads to the incorrect base being used through complimentary base pairings

20
Q

what are the effects of free radicals on nucleotide structure?

A

they disrupt base pairing in DNA replication

21
Q

what is a silent mutation?

A

mutation which has no effect on the phenotype

22
Q

what is a nonsense mutation?

A

mutation which causes a stop codon to be synthesised which shortens the protein structure

23
Q

what is a missense mutation?

A

mutation which causes the wrong amino acid to be synthesised

24
Q

how is lactose-tolerance a beneficial mutation?

A

allows a mammal to digest lactose

25
Q

what are the mutations a chromosome can undergo?

A

deletion
duplication
translocation
inversion

26
Q

deletion in a chromosome

A

section of a chromosome breaks off and is lost in the cell

27
Q

duplication in a chromosome

A

sections of a chromosome get duplicated

28
Q

translocation in a chromosome

A

section of a chromosome breaks off an joins a non-homologous chromosome

29
Q

inversion in a chromosome

A

section of a chromosome is removed, reversed and then reinstated