Mutations Flashcards

1
Q

Mutations

A

Changes in the base sequence of A GENE’S DNA that lead to formation of a new allele

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2
Q

How does a mutation lead to change in polypeptide?

A

Change in base sequence of gene’s DNA
Change in primary structure of polypeptide
Alters position of hydrogen bonds/ ionic bonds/ disulfide bridges
Change in tertiary structure of polypeptide

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3
Q

All types of mutation

A

Addition
deletion
substitution
inversion
duplication
translocation

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4
Q

Addition mutation

A

Addition of new base(s) to a gene’s DNA base sequence

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5
Q

Deletion mutation

A

Deletion of bases from a gene’s DNA base sequence

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6
Q

Substitution mutation

A

Switching one base for another in a gene’s DNA base sequence

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7
Q

Inversion mutation

A

Reversing base sequence of a gene’s DNA

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8
Q

Duplication mutation

A

Repeating of a base sequence in a gene’s DNA base sequence

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9
Q

Translocation mutation

A

A base sequence is moved from one locus on a DNA molecule to another DNA locus, on the same chromosome or on a different chromosome

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10
Q

When does translocation mutation usually occur?

A

During mistakes in crossing over in meiosis: mutated gametes more likely than body cells

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11
Q

Do mutations occur randomly?

A

Yes

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12
Q

Can you predict where mutations usually occur?

A

No

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13
Q

Effect of mutations on the organism can be….

A

Good
Bad
Neutral
Completely random which one

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14
Q

Spontaneous mutations

A

Happen most in naturally occurring processes eg DNA replication, meiosis
Randomly occur with no known cause

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15
Q

Mutagenic agents

A

Factors that increase the rate that random mutations can occur at

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16
Q

Where do gene mutations originate in?

A

DNA’s triplets of bases
Affects codons of bases on mRNA thus polypeptide’s amino acid sequence

17
Q

Why do mutations in DNA matter more than in transcribed mRNA

A

Because this mutated DNA will transcribe mRNA and effect ALL polypeptides translated from this gene
And this mutated gene will be passed onto offspring

18
Q

Degenerate

A

Most amino acids can be encoded for by more than one base triplet

19
Q

Are substitution mutations likely to affect sequence of AA on polypeptide?

A

No because genetic code is degenerate so likely the substituted base that results in a new triplet will still encode for same amino acid: no change in primary structure: no change in H/ionic/disulfide bonds: no change in tertiary structure

20
Q

Frameshift

A

Describes mutations that change the nature of base triplets downstream of the mutation
So change amino acid sequence in the polypeptide from the mutation

21
Q

Examples of frameshift mutation

A

Addition
Deletion

22
Q

How can a mutation have no effect on an individual?

A

Mutation occurred in intron/non coding sequence of DNA base sequence so will not affect translation (spliced out of mRNA)
Occurred in a recessive allele of this gene so not expressed in phenotype
Occurs at point in polypeptide that does not change tertiary structure
Substitution base = diff triplet that encodes for same AA

23
Q

How can a mutation have a positive effect on an individual?

A

Changes polypeptide due to change in AA sequence that positively changes properties of protein
Which leads to increased survival chance and increased reproductive success

24
Q

How can a mutation have a negative effect on an individual?

A

Changes polypeptide sequence due to change in AA sequence that negatively changes properties of protein
Leads to decreased survival chance and decreased reproductive success

25
Chromosome mutation
Changes in number or structure of chromosomesH
26
How do chromosome mutations differ from gene mutations/
Gene mutations occur within specific base sequence in a gene in a chromosome Chromosome mutations occur during meiosis in the number of chromosomes in each cell
27
Example of chromosome mutation
Chromosome non disjunction
28
Chromosome non disjunction
Failure of homologous chromosomes/sister chromatids to separate properly during meiosis So one gamete ends up with too many copies of the same chromosome
29
Non disjunction in meiosis 1 results
Homologous chromosomes don't separate So when sister chromatids separate in meiosis 2: 2 gametes produced that lack this chromosome 2 gametes produced that have double this chromosome as non sister chromatids both enter gamete (homologous) but sister chromatids have separated so we have 2
30
Non disjunction in meiosis 2 results
Homologous chromosomes separate as normal meiosis 2 means no separation of sister chromatids in one of the daughter cells of meiosis 1 so 1 gamete has 2 copies of same chromosome and 1 gamete does not have this chromosome
31
What causes chromosome non disjunction?
Spindle fibre failure to separate sister chromatids or homologous chromosomes