1. Briefly explain why silent mutations in the DNA sequence of a gene do not alt
ID: 49501 • Letter: 1
Question
1. Briefly explain why silent mutations in the DNA sequence of a gene do not alter the function of the protein product of that gene.
2.Briefly explain how a point mutation in the DNA sequence of a gene can alter the function of the protein product of that gene.
3.Cancer is a genetic disease. Given this fact briefly explain why the following 2 seemingly contradictory statements are true: 1) cancer is rarely directly passed on to offspring AND 2) some offspring are predisposed to develop cancer (in other words cancer runs in the family).
Explanation / Answer
THE most important feature of silent mutation is -----------
Silent Mutations is that they do not change protein function. Some people consider a silent mutation the same as a synonymous mutation, which by definition changes the DNA sequence of the gene but not the amino acid sequence of the protein. A silent mutation occurs only outside the coding region of a gene (in an intron or promoter, for example). But I think the true definition is simply a mutation which does not alter the protein function (and thus is silent because it has no phenotype). Many of these names for mutations overlap with each other.
2.
A point mutation can cause alteration in the function of the protein ----------
This can happen in many ways. A point mutation can change a normal codon into a stop codon, truncating the gene (in which case it's considered a nonsense mutation). Another way is that it can change the codon from coding for one amino acid into a codon coding for a different amino acid. If this change is major (hydrophobic changed to hydrophilic, for example) and/or occurrs in part of the gene coding for the active site of the protein, it is very likely to alter the function of the resulting protein.
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