Bacterial cells are used to express proteins from other organisms. Your lab has
ID: 95030 • Letter: B
Question
Bacterial cells are used to express proteins from other organisms. Your lab has isolated a human gene that encodes an enzyme that want to produce in a bacterial cell. You can stably transfer the human gene, along with its promoter into a bacterial cell but no human protein is made. Assume that you’ve done the procedure correctly and have established that the sequence you’ve used is the reason for the lack of protein. How can this be explained? 1.5 pts
Once you solved this initial problem, you can detect RNA from the human gene in the bacterial culture. However, the mRNA is twice as long as the mRNA isolated from this gene in humans and the enzyme coded for by the gene does not appear to be functional. Explain why. 1.5 pts
Explanation / Answer
Bacterial cells, like other prokaryotes, do not have splicing mechanism to splice off the introns (non-coding regions of the gene). The reason why no human protein is made in bacteria could be
mRNA in bacteria is twice as long as the mRNA isolated from this gene in humans, because of the absence of splicing mechanism. Introns are actually big pieces of DNA stuck in the middle of genes, during splicing the Introns are chopped out after transcription. The exons (coding sequences) are then stitched together and translated into functional proteins.
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