Question

how might a gene mutation be silent, with no observable effect on a cell or an organism?
a) many proteins are superfluous to the function of a cell. a gene mutation in a gene that encodes an unnecessary protein would have no observable effect on the cell or the organism.

b) several codons are stop codons. a gene mutation that inserts a stop codon when only a few amino acids remain in the peptide sequence would have no observable effect on the cell or the organism.

c) codons are complementary to anticodons in trna. a gene mutation that changes a codon to its anticodon would have no observable effect on the cell or the organism.

d) many amino acids are encoded by multiple codons. a gene mutation that encodes the same amino acid would have no observable effect on the cell or the organism.

Explanation:

• Option A: Cells don't have "unnecessary" proteins; most proteins have roles, so this is incorrect.
• Option B: Inserting a stop codon prematurely (even with few amino acids left) would likely truncate the protein, affecting its function, so this is wrong.
• Option C: Codons are on mRNA, anticodons on tRNA; a mutation changing a codon to an anticodon is not a valid mechanism for silent mutation, so this is incorrect.
• Option D: Due to the redundancy of the genetic code (multiple codons for many amino acids), a mutation that still codes for the same amino acid (a silent mutation) won't change the protein, so no observable effect occurs. This matches the concept of silent mutations.

Answer:

D. Many amino acids are encoded by multiple codons. A gene mutation that encodes the same amino acid would have no observable effect on the cell or the organism.