Which of the following bacterial cell types is most sensitive to radiation damage?

• A. Mycobacteria
• B. Gram-positive bacteria
• C. Archaea
• D. Gram-negative bacteria

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the nature of radiation damage in bacteria. Radiation primarily causes damage to DNA, proteins, and cellular structures, leading to cell death or mutations.
2. Step 2: Consider the structural differences between the bacterial types listed. Gram-positive bacteria have a thick peptidoglycan layer but lack an outer membrane, whereas Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane that can provide some protection.
3. Step 3: Recognize that Mycobacteria have a unique, waxy cell wall rich in mycolic acids, which can offer some resistance to environmental stresses, including radiation.
4. Step 4: Archaea often have unique membrane lipids and cell wall structures that can confer resistance to extreme conditions, including radiation.
5. Step 5: Conclude that Gram-positive bacteria, despite their thick peptidoglycan layer, are generally more sensitive to radiation damage compared to Gram-negative bacteria and other types due to the absence of an outer membrane and less protective mechanisms.