Question

mutations can be classified by their effect on the dna sequence or the resulting protein. the triplet nature of the genetic code means that base changes within coding sequences can have several different outcomes.
which of these correctly describes the effects of the different types of mutations.
choose three that apply.
a a silont mutation involves a substitution of one base, but does not change the amino acid, resulting in the same protein. the results of this mutation is most likely neutral.
b a frameshift mutation results from the deletion or insertion of a base or bases, resulting in a change to the amino acid sequence following the mutation. the results of this type of mutation often depend on the location in the sequence where it occurs.
c a nonsense mutation changes an amino acid to a stop codon, resulting in a change to the sequence the amino acid chain.
d a frameshift mutation results from the deletion or insertion of a base or bases, resulting in a change to the amino acid sequence following the mutation. these mutations are always lethal.
e a missense mutation results from the substitution of one base, changing an amino acid to another amino acid, possibly affecting protein function. the effects of this mutation can be positive, negative, or neutral.

Explanation:

• Option A: A silent mutation is indeed a base - substitution that doesn't change the amino acid (due to the degeneracy of the genetic code), and its effect is usually neutral.
• Option B: Frameshift mutations (insertion or deletion of non - multiple - of - three bases) shift the reading frame, changing the amino acid sequence downstream. The impact depends on where it occurs (e.g., near the start or end of a coding sequence).
• Option C: A nonsense mutation changes an amino - acid - coding codon to a stop codon, prematurely terminating protein synthesis and altering the amino - acid chain.
• Option D: Frameshift mutations are not always lethal. For example, if they occur near the end of a coding sequence, the resulting protein may still have some function.
• Option E: A missense mutation is a base - substitution that changes one amino acid to another. The effect can be positive (e.g., in some cases of antibiotic resistance), negative (e.g., in sickle - cell anemia), or neutral (if the new amino acid has similar properties to the original one).

Answer:

A. A silent mutation involves a substitution of one base, but does not change the amino acid, resulting in the same protein. The results of this mutation is most likely neutral.
B. A frameshift mutation results from the deletion or insertion of a base or bases, resulting in a change to the amino acid sequence following the mutation. The results of this type of mutation often depend on the location in the sequence where it occurs.
C. A nonsense mutation changes an amino acid to a STOP codon, resulting in a change to the sequence the amino acid chain.
E. A missense mutation results from the substitution of one base, changing an amino acid to another amino acid, possibly affecting protein function. The effects of this mutation can be positive, negative, or neutral.