Why can a human gene be expressed in bacteria?

Why can a human gene be expressed in bacteria?

• A. Bacteria share the same cell wall composition.
• B. The DNA structure and code are the same in bacteria and humans; the transcription/translation machinery is the same.
• C. Bacteria can edit eukaryotic genes.
• D. Only plasmids are necessary.

Answer: (B)

The key idea is that the genetic code is universal, so a gene from one organism can be read and used to make protein by another organism if it’s provided with the right bacterial signals. To express a human gene in bacteria, you place the gene into a bacterial expression system that supplies a promoter and ribosome binding site recognized by the bacterial transcription and translation machinery. You also use a version of the gene without introns (a cDNA) because bacteria don’t splice RNA. When these elements are in place, the bacterial machines can transcribe and translate the gene into protein, demonstrating why the concept described in the correct choice is the best fit. The other ideas don’t fit as well: cell wall differences don’t determine expression; bacteria generally cannot edit eukaryotic genes to make functional proteins; and while plasmids are a common tool, they’re not strictly necessary in all cases for expressing a gene in bacteria.

The key idea is that the genetic code is universal, so a gene from one organism can be read and used to make protein by another organism if it’s provided with the right bacterial signals. To express a human gene in bacteria, you place the gene into a bacterial expression system that supplies a promoter and ribosome binding site recognized by the bacterial transcription and translation machinery. You also use a version of the gene without introns (a cDNA) because bacteria don’t splice RNA. When these elements are in place, the bacterial machines can transcribe and translate the gene into protein, demonstrating why the concept described in the correct choice is the best fit.

The other ideas don’t fit as well: cell wall differences don’t determine expression; bacteria generally cannot edit eukaryotic genes to make functional proteins; and while plasmids are a common tool, they’re not strictly necessary in all cases for expressing a gene in bacteria.