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A Level Biology > 6.1 Gene Mutation > Flashcards

6.1 Gene Mutation Flashcards

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1
Q

What is a mutation?

A

Change to the quantity or structure of DNA

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2
Q

What are the 2 types of mutation?

A

Gene/point

Chromosome

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3
Q

When can a mutation be inherited?

A

If it occurs in a gamete

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4
Q

How can the rate of mutation be increased?

A

Mutagens - certain chemicals or ionising radiation

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5
Q

What does the natural rate of mutation depend on?

A

The species and locus of gene

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6
Q

What is the usual rate in plants and animals?

A

1 in 100000 per locus per generation

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7
Q

(Point) where do point mutations occur?

A

Single locus of a chromosome

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8
Q

(Point) what can a change result in?

A 
Change in DNA bases
Change in MRNA bases
Change in MRNA codon
Change in amino acids 
Change in protein structure 
Change in protein function
Change in cell function
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9
Q

(Point) what are 3 types of mutation?

A

Substitution
Deletion
Insertion

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10
Q

(Point) what occurs in substitution and what is its effect?

A

One base changed for another
Only affects one amino acid
Rest of the protein is unaffected

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11
Q

(Point) what occurs in deletion and what is its effect?

A

Base is removed
Frame shift occurs
The rest of the protein is wrong

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12
Q

(Point) what occurs in insertion and what is its effect?

A

A base is added
Frame shift occurs
Rest of the protein is wrong

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13
Q

What is a genotype?

A

Set of genes in DNA responsible for a particular characteristic

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14
Q

What is a phenotype?

A

Physical expression of a characteristic

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15
Q

(Effects) why do some mutations have no effect on the phenotype of an organism?

A

Normally functioning proteins are still synthesised

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16
Q

(Effects) what happens when a mutation has a damaging effect?

A

Negative effect
Proteins are no longer synthesised or are not functional
Interfering with essential processes

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17
Q

(Effects) what happens when a mutation is beneficial?

A

Produces a new useful characteristic

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18
Q

(Effects) give an example of a beneficial mutation:

A

Mutation in protein present in cell membranes prevents HIV binding so the person is immune

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19
Q

What is loss of a purine base?

A

Depurination

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20
Q

What is loss of a pyramidine base?

A

Depyrimidination

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21
Q

(Mutagen) give an example of a physical mutagen:

A

Ionising radiation

22
Q

(Mutagen) what does ionising radiation do/ how does it result in mutation?

A

Breaks DNA strands - some breaks can be repaired but mutations occur in the process

23
Q

(Mutagen) give an example of a chemical agent:

A

Deaminating agents

24
Q

(Mutagen) what effects do deaminating agents have/ how do they cause mutation?

A

Chemically alter DNA bases e.g. Converting cytosine to uracil

25
Q

(Mutagen) give examples of biological agents:

A

Alkylating agents
Base analogs
Viruses

26
Q

(Mutagen) what effect do alkylating agents have?

A

Methyl or ethyl groups attached to bases resulting in incorrect base pairing

27
Q

(Mutagen) what effect do base analogs have?

A

Incorporated into DNA replacing a base thus changing the sequence

28
Q

(Mutagen) what effect do viruses have?

A

Viral DNA insets itself into the genome changing the base sequence

29
Q

(Effects) what effect do silent mutations have?

A

No effect on phenotype they don’t change the proteins or activity

30
Q

(Effects) why don’t silent mutations have an effect?

A

Found in introns
Code for same amino acid (degenerate)
Change primary structure but not whole protein

31
Q

(Effects) what do nonsense mutations result in a codon becoming? What is its effect?

A

A stop codon

Results in shortened protein

32
Q

(Effects) what does a missense mutation result in?

A

Incorporation of incorrect amino acid into primary structure where protein is synthesised

33
Q

(Effects) what does the effect of the missense mutation depend on?

A

The structure and function of the protein made

34
Q

(Effects) what is a conservative mutation?

A

Amino acid change leads to another amino acid coding for having similar properties

35
Q

(Effects) what is a non conservative mutation?

A

New amino acid has different properties to the original

More likely to affect the structure and cause disease

36
Q

(Effects) what is a amorph?

A

Mutation resulting in loss of function of a protein

37
Q

(Effects) what is a hypomorph?

A

Mutation resulting in reduction in function of protein

38
Q

(Effects) what is a hypermorph?

A

Mutation resulting in gain in function

39
Q

(Effects) what do amorphic mutations result in?

A

Recessive alleles

40
Q

(Sickle cell anaemia) what happens to the erythrocytes and why?

A

Develop abnormally due to mutation in gene coding for haemoglobin

41
Q

(Sickle cell anaemia) thymine replaces adenine making the sixth amino acid what instead of what?

A

Valine instead of glutamic acid

42
Q

(Sickle cell anaemia) in homozygous individuals what is there?

A

Two copies of the gene for sickle cell anaemia

43
Q

(Sickle cell anaemia) in heterozygous individuals what is there? What is special about these individuals?

A

One copy - carriers

They can get mild symptoms, however they are resistant to malaria

44
Q

(Chromosome) what do chromosome mutations affect?

A

Whole chromosome or a no of chromosomes

45
Q

(Chromosome) what is deletion?

A

Section of chromosome breaks off and is lost in cell

46
Q

(Chromosome) what happens in duplication?

A

Sections/genes get duplicated on chromosome

47
Q

(Chromosome) what is translocation?

A

Section of one chromosome breaks off and joins to another chromosome

48
Q

(Chromosome) what is inversion?

A

Section of a chromosome breaks off, is reversed, then joins back to the chromosome

49
Q

(Chromosome) what so polysomy?

A

Gain extra copy of a whole chromosome

50
Q

(Chromosome) what is polyploidy?

A

Gain extra set of all chromosomes

A Level Biology (102 decks)

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