Question

How does steroid hormone influence the cellular activities?

• A. Changing the permeability of the cell membrane.
• B. Binding to DNA and forming a gene-hormone complex.
• C. Activating cyclic AMP located on the cell membrane.
• D. Using aquaporin channels as second messenger.

Answer 1

The Correct Option is B

Steroid hormones are a class of hormones that penetrate cell membranes and bind to specific receptors in the target cell's cytoplasm or nucleus. Let's explore how they influence cellular activities step-by-step:

1. Steroid hormones are lipid-soluble, which allows them to pass through the lipid bilayer of cell membranes easily. This characteristic distinguishes them from peptide hormones, which cannot easily penetrate the cell membrane.
2. Once inside the cell, steroid hormones bind to specific intracellular receptors. These receptors are often located in the cytoplasm or directly in the nucleus.
3. The hormone-receptor complex then translocates to the nucleus, where it binds to specific DNA sequences known as hormone response elements (HREs).
4. This binding leads to the formation of a gene-hormone complex, which directly influences the transcription of specific genes. It can either upregulate or downregulate the expression of genes, ultimately affecting protein synthesis.
5. The increase or decrease in specific protein production leads to alterations in cellular activities and functions. These may include changes in metabolism, cell growth, and differentiation—depending on the target cell and hormone type.

The correct option is: Binding to DNA and forming a gene-hormone complex.

Now, let's analyze why the other options are not correct:

• Changing the permeability of the cell membrane: While steroid hormones easily pass through cell membranes, they do not alter the membrane's permeability as part of their action mechanism.
• Activating cyclic AMP located on the cell membrane: This mechanism is more typical of peptide hormones and not steroid hormones. Peptide hormones use second messenger systems like cyclic AMP.
• Using aquaporin channels as second messenger: Steroid hormones do not utilize aquaporins as second messengers; rather, their action is primarily intracellular and genomic.

In conclusion, steroid hormones exhibit their effects by forming a gene-hormone complex and altering gene expression, which then influences cellular activities.