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
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About Viruses
Viruses are acellular infectious particles made of genetic material enclosed by a protein capsid, sometimes with a lipid envelope. Their replication depends on a host cell and may follow lytic or lysogenic cycles, so viral structure and reproduction differ fundamentally from those of cellular organisms such as bacteria.
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