Fluid mosaic model of cell membrane proposes

Options

A. A lipid bilayer with embedded proteins only
B. A lipid bilayer with proteins on the outer surface only
C. A lipid bilayer coated with proteins on both the surfaces
D. A lipid bilayer with proteins of two types, embeddec' (intrinsic) and superficial (extrinsic)

Answer

### Step-by-Step Solution:

1. **Understanding the Fluid Mosaic Model**: The fluid mosaic model describes the structure of the cell membrane, which is not a rigid structure but rather a semi-fluid or quasi-fluid one. This means that the components of the membrane are dynamic and can move laterally within the layer.

2. **Components of the Cell Membrane**: The cell membrane consists of a lipid bilayer, primarily made up of phospholipids. This bilayer serves as a barrier to most water-soluble substances.

3. **Types of Proteins in the Membrane**: The fluid mosaic model identifies two types of proteins associated with the lipid bilayer:
- **Integral (Intrinsic) Proteins**: These proteins are embedded within the lipid bilayer and can extend across the membrane. They play roles in transport and communication.
- **Peripheral (Extrinsic) Proteins**: These proteins are located on the outer or inner surface of the membrane and are not embedded within the lipid bilayer. They often serve as enzymes or structural attachments.

4. **Mosaic Arrangement**: The term "mosaic" refers to the patchwork of proteins that float in or on the fluid lipid bilayer. This arrangement allows for various functions and interactions within the membrane.

5. **Conclusion**: Based on the fluid mosaic model, the correct proposal is that the cell membrane consists of a lipid bilayer with two types of proteins: intrinsic (embedded) and extrinsic (superficial). Therefore, the answer to the question is that the fluid mosaic model proposes a lipid bilayer with proteins of two types embedded (intrinsic) and superficial (extrinsic).

### Final Answer:
The fluid mosaic model of the cell membrane proposes a lipid bilayer with proteins of two types: intrinsic (embedded) and extrinsic (superficial).

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