Reception for protein hormones are located
(a) in the nucleus
(b) in the cytoplasm
(c) on the cell surface
(d) on the endoplasmic reticulum

Options

A. in the nucleus
B. in the cytoplasm.
C. on the cell surface
D. on the endoplasmic reticulum.

Answer

To determine the location of receptors for protein hormones, let's analyze the options provided:

1. **Option A: in the nucleus**
- Protein hormones do not typically bind to receptors in the nucleus. Instead, they usually exert their effects through cell surface receptors.

2. **Option B: in the cytoplasm**
- While some hormones can have effects that involve the cytoplasm, protein hormones primarily act through receptors located on the cell surface rather than directly in the cytoplasm.

3. **Option C: on the cell surface**
- This is the most accurate option. Protein hormones bind to specific receptors located on the surface of target cells. These receptors are known as cell surface receptors. When the hormone binds to these receptors, it triggers a signaling cascade that leads to a cellular response.

4. **Option D: on the endoplasmic reticulum**
- The endoplasmic reticulum is involved in the synthesis and processing of proteins, but it is not the primary site for the reception of protein hormones.

Based on this analysis, the correct answer is **(c) on the cell surface**.

### Step-by-Step Solution:
1. **Identify the nature of protein hormones**: Understand that protein hormones are large molecules that cannot easily cross the cell membrane.
2. **Evaluate each option**:
- **Nucleus**: Not the site for protein hormone reception.
- **Cytoplasm**: Not the primary site for protein hormone reception.
- **Cell surface**: Correct, as protein hormones bind to receptors on the cell surface.
- **Endoplasmic reticulum**: Not the site for protein hormone reception.
3. **Conclude**: The receptors for protein hormones are located on the cell surface.