Question

Human genes are routinely expressed in bacteria to produce clotting factors, hormones, etc. Which of the following must be altered for bacteria to successfully synthesize human proteins? Check all that apply.

Promoter of the gene

Translation start site

Introns

Exons

Terminator of the gene

Answer 1

Promoter, introns

The promoter is the sequence on DNA which is recognised and bound by RNA polymerase. The sequence of promoter in eukaryotes and prokaryotes is quite different although it is highly conserved. Therefore to express a eukaryotic gene in bacteria, we must ensure that the gene is undergoing transcription and translation inside bacteria. For this we need a promoter which is specific to prokaryotes.

Introns are non coding sequences with are not found in prokaryotes and are exclusive to eukaryotes. Therefore if we want to express a eukaryotic gene inside a bacterial cell, then introns have to be removed.

Terminator of gene, translation start site and exon which is the coding sequence, all of them are common to both prokaryotes and eukaryotes and therefore need not be removed.

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