A biologists insert a gene from a human liber cell into chromosome of a bacterium. The bacterium then?

Question

transcribes this gene into mRNA and translates the mRNA into protein. The protein produced is useless and is found to contain many moreamino acids than does the protein made by the eukaryotic cell. explain why.

Answer 1

The mechanism of splicing (excess amino acid)and Post-translational modification (non-functional protein) is not correct. Hence, the protein is useless.

Splicing done in human is different of that compared to bacteria. This is the reason why the gene inserted to vectors are in the form of cDNA. mRNA is reverse transcribed to cDNA so that the gene only has the wanted coding sequence. The bacteria then produces the protein through only that sequence.

Post Translational Modification for human and bacteria is different. WIth different mechanism running behind, the folding, intein splicing and some other phosphorylation is NOT done. The protein has become non-functional.

Answer 2

Bacterial genes are not edited like eukaryotic genes- e.g. taking a human genomic sequence and inserting it into bacteria will not work- both exons and introns will be transcribed, and you will get a giant pile of gunk that doesn't resemble the human protein at all.

To get this approach to work, you have to use a cDNA. cDNA is just the coding sequence and is generally prepared by reverse transcription from (in this case) human mRNA.

A much bigger problem with transcription of eukaryotic genes in prokaryotic systems is that prokaryotes also do not post translationally modify proteins- stuff like glycosylation, phosphorylation that happen, and dictate the tertiary structure does not happen in prokaryotes, so the end result is different.