Answer to Question #165741 in Genetics for Sam

Question

Assess the possibility of errors occurring during the stages of protein synthesis, particularly during transcription and translation. Analyse the cause and effect of genetic mutations in DNA, including:

• Missense 

• Nonsense

• Silent

• Insertion

• Deletion

• Duplication

• frameshift

Provide examples of the impact that these errors may have on the end products of protein synthesis.

Answer 1

Protein synthesis errors may also produce polypeptides displaying a gain of toxic function. The error may confer an alternate or pathological function on an otherwise common folded protein. Oftenly errors disrupt folding, and the misfolded molecule may be toxic. The most common type of transcription error is a C to U base substitution and transitions occur more frequently than transversion epimutation events, as has been found for spontaneous mutation, therefore RNA polymerase base misincorporations appear to resemble DNA polymerase base misincorporations.

Missense

Mistake in the DNA code, one of the DNA base pairs is changed

Nonsense

Single change in DNA code produces stop codon, prematurely terminates protein synthesis

Insertion

Addition of one (or more) nucleotide base pairs into the DNA sequence

Deletion

A piece of DNA is removed from the sequence

Frameshift

Addition or deletion mutation results in a change to a gene's reading frame

Duplication

DNA is abnormally copied