What is a point mutation
-changing of a single nucleotide in mRNA sequence
Effects of point mutation and describe
1 silent mutation - changed codon may still code same aas
2 missense mutation - changed codon codes a diff aas
3 nonsense mutation - changed codon becomes termination sequence and produces truncated protein
Other mutations ( non-point mutation ) List
1 tri nucleotide repeat expansion
2 splice site mutation
3 frame shift mutation
Describe tri nucleotide repeat expansion
- codon repeated in tandem will be amplified
- too many copies of codon exist and too many aas inserted in protein
Describe Huntington disease
- codon CAG repeats will add too many glutamine in huntingtin protein
- 2• protein structure changes leading to accumulation of protein aggregates
Fragile X syndrome describe
- intellectual disease
- codon repeat expansion in UTR and decrease in protein made
- also leads to myotonic dystrophy
Describe splice site mutations
- affects ways in which Introns are removed and they can be added to Exons or Exons removed
- change sequence and diff protein coded
Describe frame shift mutations
- when 1/2 nucleotides are removed or Added from mRNA sequence
- alters reading frame ( sequence now mutated and read differently )
How does frame shift mutation lead to truncated proteins
-leads to truncated protein is termination sequence added
Effect of adding or removing a codon
- aas added
- aas lost
Effect of reading frame by removing codon
-reading frame is maintained but aas lost
Describe what type of disease cystic fibrosis is ,what it affects and ,how it’s comes about
- hereditary disease affecting pulmonary and digestive system
- loss of codon in gene
- loss of phenylalanine at 508th position ( DF508 ) of protein
- prevents normal folding of Protein CF transmembrane regulator ( CFTR )
- protein ubiquitinated
- production of thick sticky secretions in lungs and pancreas
- lung damage and digestive deficiencies
Function of CFTR
-chloride channel in epithelium cells
