Question

The activity of which enzyme is not ATP-dependent:

• A. Flippases
• B. Floppases
• C. Scramblases
• D. Sodium-potassium pump

Hint:

“Flip” and “Flop” need Energy (ATP); “Scramble” is just a chaotic, passive mix.

Answer 1

The Correct Option is C

Step 1: Concept
Membrane proteins called phospholipid translocators maintain lipid asymmetry in the cell membrane.

Step 2: Meaning
Some translocators use active transport (ATP), others facilitate passive movement.

Step 3: Analysis
Flippases and Floppases are ATP-dependent. The sodium-potassium pump is also ATP-dependent. Scramblases move phospholipids non-specifically in both directions without ATP, typically triggered by $Ca^{2+}$.

Step 4: Conclusion
Scramblase activity is not ATP-dependent.

Final Answer: (C)