Below is a partial mRNA sequence from a mutant gene in E. coli . used to answer

Question

Below is a partial mRNA sequence from a mutant gene in E. coli. used to answer the following questions.
5'... ACCCGCCACGCC... 3'

This gene is a mutant variant that severely slows the growth of the bacteria. The normal version of the encoded protein should contain the partial amino acid sequence (Nterm...T-R-N-A...Cterm). It's known that mutant forms of tRNA synthetases can charge tRNAs with a different amino acid than expected.

If a mutant synthetase gene was introduced into the E. coli, which one could produce the normal version of the encoded protein?

A. synthetase that charges an asparagine tRNA with asparagine B. synthetase that charges a histidine tRNA with asparagine C. synthetase that charges a histidine tRNA with histidine D. synthetase that charges an asparagine tRNA with histidine

Explanation / Answer

The given code 5'... ACCCGCCACGCC... 3' codes for

ACC - THR   T
CGC - ARG   R
CAC-   HIS    H
GCC - ALA   A

N - ter T-R-H-A C -ter

But normal sequence has Nterm...T-R-N-A...Cterm

In mutant synthetases Asparagine replace by Histidine.

To .produce the normal version of the encoded protein - B. synthetase that charges a histidine tRNA with asparagine

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