What are the sequences of steps in which a bacteriophage attacks bacteria and injects its DNA?
Correct answer: A. Landing → Tail contraction → Penetration → DNA Injection
- A. Landing → Tail contraction → Penetration → DNA Injection
- B. Penetration → Landing → Tail contraction → DNA Injection
- C. Tail contraction → Landing → DNA Injection → Penetration
- D. Landing → Penetration → Tail contraction → DNA Injection
Explanation
The phage first attaches itself by its tail to the cell wall of bacterium at a point called receptor site. The phage contains an enzyme called lysosome, which digest the cell wall of bacterium. Thus an opening is formed in the bacterial cell wall. The phage contracts and injects its DNA inside the host while the protein coat and the tail remain outside. Thus, Option A is correct
This question appeared on the UHS MDCAT 2014 paper, which you can sit online with every answer explained.
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