Human insulin is produced in bacteria using a cDNA copy of the insulin mRNA rather than the gene cut from human DNA. The most likely reason is that:
Answer and explanation
Correct answer: C. Bacteria cannot splice out introns
- Step 1: Human genes contain introns that are spliced out of pre-mRNA in the nucleus.
- Step 2: Bacteria have no spliceosome, so the introns would stay in the mRNA and give a faulty protein.
- Step 3: Reverse transcriptase makes cDNA from mature mRNA, which already has the introns removed.
Answer
bacteria cannot splice introns, so cDNA from mature mRNA is used.
Why not the others: The genetic code is universal; introns are not required for bacterial transcription; plasmid size is not the reason.
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