1. Determine which of the following mutations is more likely to produce a severe rather than mild phenotypic consequence(s)?
Synonymous mutations
Nonsense mutations
Missense mutations
None of the above
All of the above
2. Why do mutations in non-coding regions of a gene still have major effects on phenotypic expression?
3. Loss-of-function mutations are significantly more frequent than gain-of-function mutations. True or false?
4. Missense mutations can be classified as either "conservative substitutions" or "nonconservative substitutions." These two subclasses differ in that in a conservative mutation: (select all that apply)
a) a purine is replaced by a different purine base.
b) a pyrimidine is replaced by a purine base.
c) the same amino acid is encoded by the mutated codon.
d) a functionally similar amino acid is encoded by the mutated codon.
e) there is less effect on the protein structure and function.
5. (i) What is a nonsense mutation?
(ii) What effect do nonsense mutations have on the length of mRNA?
(iii) What effect do nonsense mutations have on the length and function of a protein?
(iv) The following DNA sequence is from the non-template strand of a gene. List all possible single point mutation events that would create nonsense mutations.
5' ATG CTG AGA TGC GAA CAG GAC 3'
(v) Which of the point mutations from part (iv) will most likely occur at the highest frequency?