In: Biology
Explain how a single point mutation in the DNA sequence can have a damaging effect on the final protein. Provide a detailed explanation and include reasoning in regard to the transcription and translation processes.
Poiint mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a sequence of DNA or RNA.
Single point mutation in DNA sequence can have damaging effect on the final protein.
For example, sickle-cell disease is caused by a single point mutation (a missense mutation) in the beta-hemoglobin gene that converts a GAG codon into GUG.
It encodes the hydrophobic amino acid valine rather than hydrophilic amino acid glutamic acid at sixth position.
Under low-oxygen conditions (being at high altitude, for example), the absence of a polar amino acid at position six of the β-globin chain promotes the non-covalent polymerisation (aggregation) of hemoglobin, which distorts red blood cells into a sickle shape and decreases their elasticity.
Sickle-Cell Anemia is an autosomal recessive disorder in which sickle-shaped cells cannot carry nearly as much oxygen as normal red blood cells and they get caught more easily in the capillaries, cutting off blood supply to vital organs.
The protein may also exhibit a "gain of function" or become activated, such is the case with the mutation changing a valine to glutamic acid in the BRAF gene. This leads to an activation of the RAF protein which causes unlimited proliferative signalling in cancer cells.
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