Which of the following statement are incorrect about receptor proteins?
I.Majority of receptor proteins are embedded in the cell membranes
II.The active site of receptor proteins opens on the inside region of the cell
III.Chemical messengers are received at the binding sites of receptor proteins
IV.Shape of receptor does not change during attachment of messenger
choose the option with all incorrect statements

Options

A. I and II
B. III and IV
C. I and III
D. II and IV

Answer

To determine which statements about receptor proteins are incorrect, let's analyze each statement one by one:

1. **Statement I: Majority of receptor proteins are embedded in the cell membranes.**
- This statement is **correct**. Most receptor proteins are indeed found embedded in the cell membranes, where they can interact with external signals.

2. **Statement II: The active site of receptor proteins opens on the inside region of the cell.**
- This statement is **incorrect**. The active sites of receptor proteins can be located either on the outside or inside of the cell, depending on the type of receptor. Therefore, it is not accurate to say that they only open on the inside region of the cell.

3. **Statement III: Chemical messengers are received at the binding sites of receptor proteins.**
- This statement is **correct**. Receptor proteins have specific binding sites where chemical messengers (like hormones or neurotransmitters) attach to elicit a response.

4. **Statement IV: Shape of receptor does not change during attachment of messenger.**
- This statement is **incorrect**. When a chemical messenger binds to a receptor protein, it typically causes a conformational change in the shape of the receptor, which is essential for the activation of the receptor and subsequent signaling.

Now, let's summarize the incorrect statements:
- Statement II is incorrect.
- Statement IV is also incorrect.

Thus, the option with all incorrect statements is **Option 4**, which includes statements II and IV.

### Summary of Incorrect Statements:
- Statement II: The active site of receptor proteins opens on the inside region of the cell. (Incorrect)
- Statement IV: Shape of receptor does not change during attachment of messenger. (Incorrect)