A mutant bacterial cell has a defective aminoacyl-tRNA synthetase that attaches a lysine to tRNAs with the anticodon AAA instead
of the normal phenylalanine. The consequence of this for the cell will be that _____. A) proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.
B) none of the options will occur; the cell will recognize the error and destroy the tRNA.
C) none of the proteins in the cell will contain phenylalanine.
D) the ribosome will skip a codon every time a UUU is encountered.
E) the cell will compensate for the defect by attaching phenylalanine to tRNAs with lysine-specifying anticodons.
A) proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.
Explanation:
Anticodon is the name given to each set of nucleotides complementary to the triads of nucleotides found in mRNA. As you may already know, each nucleotide is formed by a nitrogenous base; in the case of RNA, the nitrogenous bases are adenine (A), uracilla (U), guanine (G) and cytosine (C), each nitrogenous base binds with its complementary nitrogen base. For this reason, a codon formed by the UUU crack will have as its anticodon a crack formed by AAA.
Based on this, we can conclude that in a mutant bacteria that binds lysine to tRNAs with the AAA anticodon instead of normal phenylalanine, proteins in the cell will include lysine instead of phenylalanine at the amino acid positions specified by the UUU codon.
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