Answer
The correct answer is:
b. They are lipids that enter the cell and bind to receptors on the nucleus.
Explanation
Steroid hormones are derived from cholesterol and are therefore lipophilic (fat-soluble). This allows them to easily pass through the lipid bilayer of the cell membrane and enter the cell. Once inside, they bind to specific receptors located in the cytoplasm or directly on the nucleus. This receptor-hormone complex then acts as a transcription factor, influencing gene expression and thus the cell's function.
Here is a simplified representation of the process:
- Steroid hormone diffuses through the cell membrane.
- The hormone binds to its specific receptor in the cytoplasm or nucleus.
- The hormone-receptor complex acts as a transcription factor, influencing gene expression.
This process distinguishes steroid hormones from peptide hormones, which are water-soluble and cannot pass through the cell membrane. Instead, peptide hormones bind to receptors on the cell surface, triggering a cascade of intracellular events.
Hormone Type | Solubility | Receptor Location |
---|---|---|
Steroid | Lipophilic | Inside the cell |
Peptide | Hydrophilic | Cell surface |
Remember, while both types of hormones can influence cell function, they do so through different mechanisms due to their different chemical properties.