A mutant B. adonis bacterium has a nonsense suppressor tRNA that inserts glutami

Question

A mutant B. adonis bacterium has a nonsense suppressor tRNA that inserts glutamine (Gln) to match UAG (but not other nonsense) codons. [This species does not modify wobble position C residues to k2C and does not have tRNAPyl.] What is the anticodon of the suppressing tRNA? Indicate the 5' and 3' ends. What is the sequence of the template strand of the wild-type tRNAGln-encoding gene that was altered to produce the suppressor, assuming that only a single-base-pair alteration was involved? What is the minimum number of tRNAGln genes that could be present in a wild-type B. adonis cell? Describe the corresponding anticodons.

Explanation / Answer

The original sequence would have been UAG but it was altered to CAG whcih codes for glutamine. Only a single letter substitution has ocurred from U to C. The anticodon for the altered sequence would be 3'-GUC-5'. The tRNA does not modify the wobble base C in the third position. For wobble bases, G pairs with U.

The normal anticodon would be 3'-AUC-5'

There are only 2 coding for gln so there would be atleast 2 genes.

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