Integral cell membrane proteins

Options

A. are partially embedded in lipid layers
B. are completely embedded in lipid layers
C. show leteral but not vertical movements within bilayer of lipid
D. All of these

Answer

### Step-by-Step Solution:

1. **Definition of Integral Cell Membrane Proteins**:
Integral cell membrane proteins, also known as intrinsic proteins, are proteins that are embedded within the lipid bilayer of cell membranes. They can be partially or completely embedded in the lipid layer.

2. **Structure and Composition**:
These proteins typically have one or more segments that interact with the hydrophobic (water-repelling) fatty acid tails of the phospholipids that make up the membrane. This interaction is due to the presence of hydrophobic side chains in the protein structure.

3. **Comparison with Peripheral Proteins**:
Unlike integral proteins, peripheral proteins are not embedded in the lipid bilayer; instead, they are located on the surface of the membrane. This distinction is important when discussing the roles and functions of different types of membrane proteins.

4. **Movement of Integral Proteins**:
Integral membrane proteins are capable of lateral movement within the lipid bilayer. This means they can move sideways within the plane of the membrane. However, some transmembrane proteins can also exhibit vertical movement, which is important for transport processes across the membrane.

5. **Conclusion**:
Based on the characteristics discussed, the correct answer to the question is "all of these". This includes:
- Integral proteins being partially or completely embedded in the lipid layer.
- Their ability to show lateral movement within the lipid bilayer.
- The distinction that some transmembrane proteins may show vertical movement.