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16 Cards in this Set
- Front
- Back
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Mutation
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Mutations are the changes in the genome of an organism. They occur spontaneously and are inevitable. Few mutation are advantageous, most are neutral or deleterious.
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Mutations may result from:
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- Mistakes in DNA replication;
- Damage: radiation, chemical mutagens. - Insertion or transposon (mobile genetic element). |
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Do mutations outside coding regions lead to any changes?
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Yes, they lead to phenotypic changes if they alter gene expression, e.g. reduce the level of transcription.
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Point mutations.
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Single nucleotide changes.
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Name two substitutions.
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Transition and transversion.
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Transition.
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Mutation causing changes from pyrimidine to pyrimidine (CT) or
Purine to purine (AG). |
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Transversion
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Mutation causing changes from pyrimidine to purine or purine to pyrimidine.
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What mutation results in frameshift?
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Deletion or insertion (if not in groups of 3).
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Inversion
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Mutation in which order of block is reversed (break and rejoin).
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Translocation.
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Mutation in which part of a chromosome is moved into a new location (break and rejoin). e.g. Down syndrome - trisomy 21.
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Synonymous mutation.
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New codon codes for the same amino acid - no change in protein, e.g. ACT mutated to ACA - no change in amino acid, still thr.
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Non-synonymous mutation.
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New codon codes for a different amino acid - change in protein, for example, ACT change to GCT - amino acid change from thr to ala.
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What do mutation in the somatic cell lead to?
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Cancer.
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Ames test.
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Ames test is in vitro test to detect environmental mutagens.
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How does radiation affect the body?
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Radiation may cause single and double strand breaks in DNA. UV radiation - creates thymine dimers in DNA.
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Name several mutation repair mechanisms.
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- Proof-reading function of DNA polymerase corrects errors in DNA replication;
- Repair mechanisms to eliminate thymine dimers caused by UV radiation; - Repair mechanisms can correct mispairing, but must be able to recognise which strand is wrong. |
