Gene Mutation Flashcards

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1
Q

Germ-line mutations

A

mutations passed through the gametes

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2
Q

Somatic Cell Mutations

A

Show patches of affected areas, no gametes will carry the mutations.

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3
Q

Spontaneous Mutations

A

Occur naturally. A baby will have an average of 60 new mutations, 90% will be in non-coding regions

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4
Q

What percentage of DNA actually codes for proteins?

A

1.5%

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5
Q

What are induced mutations caused by?

A

Mutagens

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6
Q

Chromosomal mutation effects can result in:

A

Duplications
Inversions
Deletions
Insertions
Translocation

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7
Q

Mutations in nucleotide sequences include:

A

point mutations
base substitutions
insertions
deletions

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8
Q

A point mutation is:

A

A substitution of a single base nucleotide with another nucleotide (doesn’t effect the number of nucleotides)

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9
Q

Silent Mutation

A

Does not change the amino acid encoded by the codon and includes mutations occuring in introns.

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10
Q

Missense mutations

A

Changes the amino acid encoded by the codon.

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11
Q

Why would a missense mutation be harmless?

A

If the amino acid that the changed codon produces is chemically similar to the one the non-mutated gene codes for, or if it is in an unimportant area.

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12
Q

Why would a missense mutation be harmful?

A

A chemically different amino acid can cause changes in structure and function, such as in sickle cell anaemia in which the change from Glu to Valine results in a structural change in the RBS that effects its function.

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13
Q

Nonsense Mutation

A

Changes an amino acid codon to a termination (stop codon). the resulting amino acid is shortened.

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14
Q

Sense Mutations

A

Converts a stop codon to a sense codon.

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15
Q

What causes a Frameshift Mutation?

A

Insertions or deletions of a single base pair.

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16
Q

Loss of Function mutation.

A

A mutational effect that impedes function.
Mostly recessive, but can be dominant.

17
Q

Null Mutations

A

a mutational effect that abrogates/blocks function.

18
Q

Trinucleotide Repeat Diseases

A

Genetic diseases characterised by the presence of unstable and abnormal expansions of DNA-triplets.

19
Q

abnormally repeated DNA-triplets may cause:

A

gene inactivation or production of a toxic protein may be caused by:

20
Q

Genetic Anticipation

A

Severity of mutation increases with each successive generation.

21
Q

Cystic Fibrosis is what type of disease?

A

A Trinucleotide Repeat Disease

22
Q

Lethal mutations can be carried on to successive generations by…

A

slow onset.

23
Q

Mutations such as trinucleotide repeat diseases can increase in severity with each successive generation due to:

A

genetic anticipation.

24
Q

Cystic Fibrosis is cause by what a mutation of which gene?

A

The CFTR gene.

25
Q

What is the function of the protein coded for on the CFTR gene?

A

It is an ion channel for fluid homeostasis and when mutated, causes a build up of fluid in the lungs.

26
Q

The position of the mutation in the CFTR gene effects what?

A

Gene phenotype and severity of protein function. Can be partially active or completely inactive - which affects drug function.

27
Q

Mutagens

A

A physical or chemical agent that changes the DNA of an organism and increases the frequency of mutations.

28
Q

What mutagens can cause chemical modifications to DNA in the intracellular environment?

A

Free radicals and Reactive Oxygen Species

29
Q

How do free radicals and reactive oxygen species chemically modify DNA?

A

Can cause loss of bases and single strand breaks by oxidising the nucleotides and thus affecting their chemical structure. (steals their electrons)

30
Q

What are some examples of mutagens from the external environment?

A

Radiation
Chemicals
Base Analogues
Base Modifiers

31
Q

How does ionising radiation cause DNA mutations?

A

Ionising radiation causes the formation of free radicals and reactive oxygen species that oxidises nucleotides.

32
Q

How does non-ionising radiation (such as UVB) cause DNA mutations?

A

The biological effects observed for non-ionising radiation includes production of free radicals, double stranded DNA breaks and induced thymine dimers.

33
Q

How do chemical mutagens cause DNA mutations?

A

They intercalate between base pairs of DNA and causes separation of base pairs and unwinding. They make good nucleic acid stains.

34
Q

Base analogues have a similar structure to…

A

nucleotide bases and are incorporated into the DNA.

35
Q

How do Base Analogue mutagens cause mutations?

A

They can cause mispairing during DNA replication.

36
Q

Two types of Base Modifiers are:

A

Alkylating Agents
Mustard gas

37
Q

Alkylating agents act as mutagens by:

A

transferring alkyl groups (methyl/ethyl) to nucleotide bases.

38
Q

What does Mustard Gas do to Guanine?

A

It akylates guanine leading to cellular death and cancer.