Why is a gene for antibiotic resistance often included in a plasmid used to transform bacteria?
Answer and explanation
Correct answer: A. So that bacteria which took up the plasmid can be identified by growing on antibiotic
- Step 1: Only a small fraction of bacteria take up the recombinant plasmid.
- Step 2: When plated on antibiotic, only bacteria carrying the resistance gene on the plasmid survive, which identifies the transformed cells.
Answer
So that bacteria which took up the plasmid can be identified by growing on antibiotic.
Why not the others: So that the bacteria can make the antibiotic for use as a medicine: the marker gene gives resistance, not antibiotic production. So that the plasmid can replicate inside the bacterial cell: replication is controlled by the origin of replication. So that the plasmid can be cut by the restriction enzyme: restriction sites are separate from the resistance gene.
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