Module 1 - Unit 2

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  • Created by: S.L.S_10
  • Created on: 12-04-15 16:19

Mutations - DNA mutations - Insertion and Deletion

One or more nucleotide pairs is inserted into or deleted from the a length of DNA. Insertion and deletion cause dramatic changes in the triplet sequenceThese mutations affect the way in which the triplets of bases is "read" during DNA replication. This causes a frameshift. 

Frameshift = The addition or deletion of nucleotides causes a shift in the reading frame of the codons in mRNA --> alterations to the amino acid sequence at translation of DNA replication. Every triplet of bases after the change in the sequence is altered. 


  • Adding a new amino acid, which changes the sequence. 
  • Example: Huntington's Chorea = insertion of a triplet nucleotide repeat changes the protein. Damages to the nerve cells in the brain, inherited and progressive disease, which causes loss of motor control and dementia. 


  • Removing an amino acid, which changes the sequence. 
  • Example: Cystic Fibrosis = deletion of a triplet pair causes the loss of an amino acid. Stickier mucus, which leads to lung congestion and reduced gaseous exchange. 
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