Question

Oestrogen and testosterone are steroid hormones and are most likely bind to
A) Membrane ions channels
B) Enzyme-linked membrane receptors
C) G-protein linked membrane receptors
D) Cytoplasmic receptors

Answer 1

Hint: They are also known as intracellular or internal receptors that are present in the cell nucleus. Nuclear receptors are an example of this category. They are basically in contact with hydrophobic ligand molecules so that they are able to travel across the plasma membrane.

Complete Answer:
- Steroid hormones belong to the category of the chemical compounds that are called steroids.
- Steroid hormones are basically lipophilic in nature. This is because lipids which are present in the cell membrane do not halt the entry of lipophilic molecules in the cell. So, that is why steroid hormones easily diffuse through the cell membrane.
- When the steroid hormones enter into the cell, they either bind to nucleic receptors or cytoplasmic receptors. So, this is because oestrogen and testosterone are steroid hormones that are most likely bound to cytoplasmic receptors.

Thus, the correct answer is option D i.e., Cytoplasmic receptors.

Additional information:
- Membrane ion channel is the channel which allows the ion to pass through the pore-forming membrane proteins of the channel.
- They play a vital role in the resting membrane potential, controlling the flow of ions and also helps in regulating the cell volume.
- Enzyme-linked membrane receptors are also called catalytic membrane receptors. They have extracellular ligand binding which performs the catalytic action.
- G-protein linked membrane receptors are also called heptahelical receptors which have seven transmembrane receptors.

Note: Cytoplasmic receptors present the nucleus of the cell and in the cytoplasm, which respond to the hydrophobic ligand molecules for traveling across the plasma membrane. Steroid hormones originate from the chemical compound known steroids that are lipophilic in nature.