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Biology: Genetics T1 > Mutations > Flashcards

Mutations Flashcards

1
Q

define mutation

A

the changing of a gene that results ina variant form that is permenant

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2
Q

define mutagen

A

any environmental agent that causes a mutation

eg. chemical, biological, physical

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3
Q

What causes a mutation?

A
  • can occur spontaneously
  • can be caused by a mutagens
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4
Q

Examples of chemical mutagen agents

A

exposure to:
* tar
* benzene
* asbestos

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5
Q

Examples of biological mutagen agents

A
  • viruses
  • bacteria
  • fungi
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6
Q

Examples of physical mutagen agents

A

high-energy ionising radiation:
* UV light
* x-rays
* gamma rays

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7
Q

What are the 2 different types of mutations?

A
  1. point mutations
  2. chromosomal mutations
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8
Q

What does a point mutation occur with?

A

a single base pair

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9
Q

What are the 3 types of point mutations?

A
  1. point substitution
  2. point insertion
  3. point deletion
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10
Q

What happens in a point substitution?

A

one base is subsituted to another base

the nucleotide is subsituted

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11
Q

What happens in a point insertion?

A

One base is inserted into the sequence
* FRAMESHIFT occurs: all following bases shift over/are affected

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12
Q

What happens in a point deletion?

A

One base is deleted from the sequence
* FRAMESHIFT occurs: all following bases shift over/are affected

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13
Q

What is an example of a chromosomal disorder?

A

trisomy 21

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14
Q

What are the 4 types of chromosomal mutations?

A
  1. chromosome deletion
  2. chromosome duplication
  3. chromosome inversion
  4. chromosome translocation
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15
Q

What happens in a chromosome deletion?

A

a section of the chromosome breaks off and disappears

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16
Q

What happens in chromosome duplication?

A

a section of the chromosome is copied and added on

17
Q

What happens in a chromosome inversion?

A

a section of the chromosome is detached, rotated 180° and reattached

18
Q

What happens in a chromosome translocation?

A

a section detaches from one chromosome and reattaches to a different chromosome

19
Q

What are the 4 consequences of point mutations?

A
  1. nonsense mutation
  2. missense mutation
  3. silent mutation
  4. frameshift
20
Q

What happens in a nonsense mutation?

what happens, effects on resultant polypeptide, effects on phenotype

A

a triplet codon is changed to a stop codon
* resultant polypeptide is cut short
* MAJOR change to phenotype

21
Q

What happens in a missense mutation?

what happens, effects on resultant polypeptide, effects on phenotype

A

a triplet codon is change to code for a different amino acid
* resultant polypeptide is LESS functional
* MINOR change to phenotype

22
Q

What happens in a silent mutation?

what happens, effects on resultant polypeptide, effects on phenotype

A

a triplet codon is changed but codes for the same amino acid
* resultant polypeptide is unchanged
* NO change to phenotype

23
Q

What happens in a Frameshift mutation?

what happens, effects on resultant polypeptide, effects on phenotype

A

everything shifts over
* resultant polypeptide’s amino acid sequence completely changes
* MAJOR change to phenotype

can only occur in insertion or deletion

24
Q

What are the consequences of chemical mutations?

(2 possible effects)

A
  1. could affect phenotype
  2. likely to lead to amino acid sequence change in resultant polypeptide
25
Q

Where does a somatic mutation occur?

A

in a NON-SEX CELL

26
Q

What are the effects of a somatic mutation

A
  • can’t be passed on to offspring
  • can be passed on in mitotic cell division
  • affects a localised part of the organism
27
Q

Where does a germline mutation occcur?

A

in a cell that will BECOME a SEX CELL

28
Q

What are the effects of a germline mutation?

A
  • will be passed down to offspring (and will be in all cells of the offspring) - can potentially affect the whole organism of the offspring
  • is a new allele in the population

Biology: Genetics T1 (9 decks)

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