Question

Arrange the steps of life cycle of phage T4 in correct sequence. A. Lysis of the host cell
B. Injection of phage DNA
C. Synthesis and assembly of phage components
D. Adsorption of the phage
E. Degradation of host DNA
Choose the correct answer from the options given below :

• A. \(E, A, D, B, C\)
• B. \(A, D, B, C, E\)
• C. \(D, B, C, E, A\)
• D. \(D, B, E, C, A\)

Hint:

Remember the lytic cycle sequence: \[ \text{Attachment} \rightarrow \text{Penetration} \rightarrow \text{Biosynthesis} \rightarrow \text{Assembly} \rightarrow \text{Lysis} \]
• T4 phage infects E.coli
• Lytic cycle results in destruction of host cell

Answer 1

The Correct Option is D

Concept: Bacteriophage T4 follows a lytic life cycle in which the virus infects a bacterial cell, replicates, and finally lyses the host cell to release progeny phages. Major stages of the lytic cycle include:
• Adsorption
• Penetration
• Host DNA degradation
• Biosynthesis of viral components
• Assembly
• Lysis

Step 1: Adsorption of the phage. The first step is attachment of phage T4 to the bacterial surface receptors: \[ \boxed{D} \] This process is called: \[ \text{Adsorption} \]

Step 2: Injection of phage DNA. After attachment: \[ \text{Phage injects its DNA into the bacterial cell} \] Thus: \[ \boxed{B} \]

Step 3: Degradation of host DNA. Phage enzymes degrade the bacterial chromosome: \[ \boxed{E} \] This redirects cellular machinery toward viral replication.

Step 4: Synthesis and assembly of phage components. The host machinery synthesizes:
• Phage DNA
• Capsid proteins
• Tail fibers These components assemble into mature phage particles. Thus: \[ \boxed{C} \]

Step 5: Lysis of the host cell. Finally: \[ \text{Host bacterial cell lyses} \] releasing newly formed phages. Thus: \[ \boxed{A} \] Therefore, the correct sequence is: \[ \boxed{D \rightarrow B \rightarrow E \rightarrow C \rightarrow A} \] Hence, the correct answer is: \[ \boxed{(D)\ D, B, E, C, A} \]