The Question is from neet-botany cell-biology cell-membrane, and it was created by the author D VINOD

Question

The cell membrane maintains a distinct phospholipid composition between its inner and outer leaflets.  Which of the following transport mechanisms is primarily responsible for establishing and maintaining this asymmetry?

D VINOD · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
 **Primary Concept**: Membrane asymmetry and lipid transport
 **Related Topics**: Cell membrane structure, phospholipid bilayer, membrane fluidity, active transport
 **Prerequisites**: Understanding of the phospholipid bilayer structure and different types of membrane transport.
## SOLUTION PATHWAY
**Given Information**:
  The cell membrane shows asymmetry in phospholipid composition between its inner and outer leaflets.
  We need to identify the transport mechanism responsible for this asymmetry.
**Method & Steps**:
 1. Analyze the given options and their functions.
  Reasoning: Simple diffusion and facilitated diffusion are passive transport mechanisms that do not actively move lipids across the membrane.  Ion channels are specific for ions, not lipids.
  Formula/Rule: N/A
 2. Consider the role of flippases.
  Working: Flippases are enzymes that catalyze the movement of phospholipids from one leaflet of the bilayer to the other. This is an active process, requiring energy, and is crucial for establishing and maintaining the asymmetric distribution of phospholipids.
  Key Point:  Flippases are responsible for the transbilayer movement of phospholipids, which is essential for membrane asymmetry.
 3. Determine the correct answer.
  Result: Flippases are the primary mechanism responsible for the asymmetric distribution of phospholipids in the cell membrane.
  Verification:  The other options do not directly contribute to the active transport and repositioning of phospholipids across the bilayer.
 ## OPTION ANALYSIS
A :x: Simple diffusion is a passive process and does not explain the energy-dependent asymmetry.
B :x: Facilitated diffusion is also passive and does not account for the active transport of lipids across the bilayer.
C ✓: Flippases actively transport phospholipids between leaflets, creating and maintaining the asymmetry.
D :x: Ion channels are involved in ion transport, not lipid transport.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing passive and active transport mechanisms: Remember that flippases require energy to move phospholipids against a concentration gradient.
  2.Overlooking the enzymatic nature of flippases:  They are not simply channels; they actively catalyze the flip-flop of phospholipids.
 **Quick Tips**:
  1.Think about the energy requirement:  Asymmetry requires active transport, pointing towards flippases.
  2.Remember the function of flippases: They are lipid translocators.

D VINOD · Answer

Simple diffusion

D VINOD · Answer

Facilitated diffusion

D VINOD · Answer

The correct Option is "Flippases"

D VINOD · Answer

Ion channels

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