Question

Arrange the steps of endospore formation in correct order :
A. Cortex and spore coat formation
B. Maturation and release of endospore
C. DNA replication and axial filament formation
D. Engulfment of forespore
E. Asymmetric septum formation
Choose the correct answer from the options given below :

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

Hint:

Remember the sequence of sporulation: \[ \text{DNA replication} \rightarrow \text{Septum formation} \rightarrow \text{Engulfment} \rightarrow \text{Coat formation} \rightarrow \text{Maturation} \]
• Endospores are highly resistant to:
• Heat
• Radiation
• Chemicals
• Desiccation

Answer 1

The Correct Option is D

Concept: Endospore formation (sporulation) is a survival mechanism used by certain bacteria such as: \[ \textit{Bacillus} \quad \text{and} \quad \textit{Clostridium} \] Endospores are highly resistant dormant structures formed under unfavorable environmental conditions. Major stages of sporulation include:
• DNA replication
• Septum formation
• Forespore engulfment
• Cortex and coat formation
• Spore maturation and release

Step 1: DNA replication and axial filament formation. The first stage involves: \[ \text{Replication of bacterial DNA} \] followed by arrangement of DNA into an axial filament. Thus, the first step is: \[ \boxed{C} \]

Step 2: Asymmetric septum formation. Next: \[ \text{An asymmetric septum develops} \] which separates the forespore from the mother cell. Thus: \[ \boxed{E} \]

Step 3: Engulfment of forespore. The mother cell membrane engulfs the forespore: \[ \boxed{D} \] resulting in a double-membraned forespore.

Step 4: Cortex and spore coat formation. Protective layers then develop around the forespore:
• Cortex
• Spore coat Thus: \[ \boxed{A} \]

Step 5: Maturation and release of endospore. Finally:
• Endospore matures
• Mother cell lyses
• Mature spore is released Thus: \[ \boxed{B} \] Therefore, the correct order is: \[ \boxed{C \rightarrow E \rightarrow D \rightarrow A \rightarrow B} \] Hence, the correct answer is: \[ \boxed{(D)\ C, E, D, A, B} \]