Why can a bacterial cell produce a human protein from a human gene?

Why can a bacterial cell produce a human protein from a human gene?

• A. Because bacteria share the same genetic code and transcription/translation mechanisms.
• B. Because they can modify the human gene to fit bacterial machinery
• C. Because the universal genetic code allows translation of human genes in bacteria
• D. Because plasmids replicate only in bacteria

Answer: (C)

The key idea is that the genetic code is universal. Codons specify the same amino acids in bacteria as in humans, so a bacterial ribosome reads a human gene and builds the same protein, provided the gene is prepared for bacterial expression. In practice, that means using a version of the gene without introns (often a cDNA), and including bacterial-friendly elements like a promoter and a ribosome binding site to drive transcription and initiation of translation. Codon usage can also be optimized so the bacteria translate efficiently. The other statements aren’t the main reason. Bacteria do not use human regulatory signals directly, so simply sharing transcription/translation machinery isn’t enough—the promoter and other regulatory parts must be compatible with bacterial systems. Removing introns and adding appropriate bacterial expression signals are necessary steps. The fact that the gene is delivered on a plasmid is a practical method for getting the gene into the bacteria, not the reason translation can occur.

The key idea is that the genetic code is universal. Codons specify the same amino acids in bacteria as in humans, so a bacterial ribosome reads a human gene and builds the same protein, provided the gene is prepared for bacterial expression. In practice, that means using a version of the gene without introns (often a cDNA), and including bacterial-friendly elements like a promoter and a ribosome binding site to drive transcription and initiation of translation. Codon usage can also be optimized so the bacteria translate efficiently.

The other statements aren’t the main reason. Bacteria do not use human regulatory signals directly, so simply sharing transcription/translation machinery isn’t enough—the promoter and other regulatory parts must be compatible with bacterial systems. Removing introns and adding appropriate bacterial expression signals are necessary steps. The fact that the gene is delivered on a plasmid is a practical method for getting the gene into the bacteria, not the reason translation can occur.