Which phrase does not describe one of the functions of proteins of the plasma membrane?

Options

A. Forming a channel through the membrane
B. Initiating the replication of the genetic material
C. Binding to a substance to carry it through the membrane
D. Acting as a receptor for substances external to the cell

Explanation

To determine which phrase does not describe one of the functions of proteins of the plasma membrane, we will analyze each of the provided options based on our understanding of the roles of plasma membrane proteins.

### Step-by-Step Solution:

1. **Understanding Plasma Membrane Proteins**:
- The plasma membrane consists of a phospholipid bilayer with embedded proteins. These proteins can be integral (spanning the membrane) or peripheral (attached to the surface).

2. **Analyzing the Options**:
- **Option 1**: "Forming the channel through the membrane"
- This describes a function of integral proteins that create channels for substances to pass through the membrane.

- **Option 2**: "Initiating the replication of the genetic material"
- This function does not relate to plasma membrane proteins. The initiation of genetic material replication is typically carried out by specific enzymes and proteins found within the nucleus, not in the plasma membrane.

- **Option 3**: "Binding to a substance to carry it through the membrane"
- This is a function of carrier proteins that bind to specific substances and facilitate their transport across the membrane.

- **Option 4**: "Acting as a receptor for substances external to the cell"
- This describes the role of receptor proteins that bind to signaling molecules (ligands) and trigger cellular responses.

3. **Identifying the Incorrect Function**:
- After analyzing all options, we can conclude that "Initiating the replication of the genetic material" is the only phrase that does not describe a function of proteins of the plasma membrane.

### Final Answer:
The phrase that does not describe one of the functions of proteins of the plasma membrane is: **"Initiating the replication of the genetic material."**

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