Bacteria and archaea are similar in which of the following characteristics?

• A. Lack of a membrane-bound nucleus
• B. Sensitivity to antibiotics such as penicillin
• C. Presence of peptidoglycan in the cell wall
• D. Membrane lipids composed of fatty acids linked by ester bonds

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the basic cellular structure of bacteria and archaea. Both are prokaryotes, meaning they do not have a membrane-bound nucleus. This is a fundamental similarity between the two groups.
2. Step 2: Analyze the sensitivity to antibiotics such as penicillin. Penicillin targets peptidoglycan synthesis, which is present in bacterial cell walls but absent in archaea. Therefore, sensitivity to penicillin is not a shared characteristic.
3. Step 3: Examine the presence of peptidoglycan in the cell wall. Bacteria have peptidoglycan in their cell walls, but archaea do not; archaea have different cell wall compositions, such as pseudopeptidoglycan or other polymers.
4. Step 4: Consider the composition of membrane lipids. Bacterial membrane lipids are fatty acids linked by ester bonds, whereas archaeal membrane lipids have ether bonds linking isoprenoid chains to glycerol. This difference means membrane lipid composition is not a similarity.
5. Step 5: Conclude that the shared characteristic between bacteria and archaea is the lack of a membrane-bound nucleus, which defines them both as prokaryotes.