gene mutation

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  • Created by: emma
  • Created on: 22-04-13 14:13
what is a mutation?
any change in the quantity or structure of an organisms DNA
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what is a non-sense mutation?
when a base substitution results in a stop codon being coded for
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what is a mis-sense mutation?
when a base substitution results in a different amino acid being coded for
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what is a silent mutation?
when a base substitution results in the same amino acid being coded for (the genetic code is degenerate)
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what is a deletion mutation?
when one nucleotide is lost from the normal DNA sequence. it results in a frame shift where the gene is read in the wrong three base triplets. if it occurs at the start of a sequence, every triplet will be altered.
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what are mutagenic agents? give examples.
outside factors that increase the basic mutation rate. examploes: high-energy radiation (dissrupts DNA molecule) and Chemicals which alter DNA structure/ interfere with transcription
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what is the role of proto-oncogenes?
they stimulate cell division
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what is the role of tumor supressor genes?
they slow cell division
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how do proto-oncogenes switch on the genes necessary for DNA replication?
1)growth factors attach to receptor protein on cell surface membrane. relay proteis in cytoplasm 'switch-on' necessary
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what causes proto-oncogenes to become oncogenes?
a gene mutation
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how do oncogenes affect cell division?
1) permenantley activates the CSM receptor protein so that cell division is switched on in the absence of growth factors 2) it may code for a growth factor that is produced in excessive amounts, stimulating excessive cell division
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what happens if a tumour supressor gene becomes mutated?
it is inactivated. it stops inhibiting cell division. cell division increases. some mutant cells survive, reproduce themselves and form tumors.
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Card 2

Front

what is a non-sense mutation?

Back

when a base substitution results in a stop codon being coded for

Card 3

Front

what is a mis-sense mutation?

Back

Preview of the front of card 3

Card 4

Front

what is a silent mutation?

Back

Preview of the front of card 4

Card 5

Front

what is a deletion mutation?

Back

Preview of the front of card 5
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