Why can a human gene not be expressed directly by a bacterium unless it is first made as complementary DNA (cDNA)?
Answer and explanation
Correct answer: A. Bacteria cannot splice out introns
- Step 1: Human genes contain introns.
- Step 2: Bacteria cannot splice them, so cDNA made from mature mRNA by reverse transcriptase (introns already removed) is used.
Answer
Bacteria cannot splice out introns.
Why not the others: Bacteria cannot make mRNA: bacteria transcribe their own genes. Bacteria have no ribosomes: bacteria use ribosomes to translate. Human DNA is destroyed by bacterial plasmids: plasmids carry genes and do not destroy DNA.
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