Point mutations are those that alter a single base pair or base location, and include substitutions and frameshift mutations. They can range in severity from no phenotypic change to complete loss of function. Rank the following point mutations in order of least damaging to most damaging if they occur in the middle of the coding sequence of a polypeptide.

a. Missense
b. Silent
c. Nonsense
d. Frameshift

order of least damaging is b, a, c and d

Explanation:

The 4 kinds of point mutations here present different consequences after a change of a single base pair. The silent point mutation is the least damaging because the alteration of the nucleotide does not implies on a different codon. Missense and nonsense point mutations will imply on a change of a entire different codon and a change of a entire codon to a stop codon, respectively. The missense could be a less aggressive mutation than a nonsense because the codon change may affect only in a small proportion of the entire protein, but the nonsense can be very aggressive by making the protein smaller than it is. The frameshift can cause severe modifications on the whole final protein because almost every codon might code for a different aminoacid leading to a whole new protein.