T2L9 Mutations and CF Flashcards

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1
Q

Explain the genetic cause of cystic fibrosis (10)

A
  • A mutation is a change in the sequences in a gene
  • This occurs in DNA during DNA replication
  • This means that during protein synthesis, the mRNA transcribed from the DNA will have the mutation
  • The ribosome will then match the wrong tRNA anticodon to the mRNA codon
  • Therefore the wrong amino acid will be added to the polypeptide chain
  • The protein’s primary structure will be wrong
  • This means that the wrong bonds will form and the protein will not fold correctly in its tertiary structure
    -This means the shape of the protein will be wrong and so it cannot carry out its function (of transporting chloride ions across the membrane)
  • The gene codes for the CFTR protein
  • In CF patients the CFTR protein is missing/ in smaller number/ non-functional
  • The protein’s job is to allow Cl- ions put of epithelial cells
  • In CF patients the ions don’t leave the cells
  • This means water isn’t drawn out of epithelial cells
  • So mucus remains thick ad sticky
  • Thick mucus causes symptoms
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2
Q

Name 5 types of mutation

A
  • Translocation
  • Deletion
  • Duplication
  • Inversion
  • Insertion
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3
Q

Describe a deletion mutation

A

When a section of the chromosome/gene is missing

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4
Q

Describe a duplication mutation

A

When a section of genetic code is repeated within the chromosome

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5
Q

Describe an inversion mutation

A

The genetic information in part of a chromosome is in reverse order

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6
Q

Describe an insertion mutation

A

Part of one chromosome is inserted into another chromosome
e.g
111122223333
44445555
goes to

1111223333
4444225555

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7
Q

Describe a translocation mutation

A

When two different chromosomes have exhanged pieces

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8
Q

Demonstrate the affect of missing bases

A

AAC CAA TGC CAT
AAC CAA CAT
this would mean a whole amino acid would be missing from the polypeptide chain

or

AAC CAA TGC CAT
AAC CAT GCC AT-

in this case the second A of CAA is missing. This means that not only would one amino acid change - but so would all of the following ,utations TGC has become GCC and this may or may not code for a different polypeptide chain

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