Which type of hormones will pass through the cell membrane?

Steroid hormones are lipid-soluble molecules that can easily cross the cell membrane due to their hydrophobic nature. The cell membrane is primarily composed of a phospholipid bilayer, which provides a barrier to water-soluble substances. Since steroid hormones are derived from cholesterol, they are structurally similar to the lipids that make up the membrane, allowing them to diffuse directly through it.

Once inside the cell, steroid hormones can bind to specific intracellular receptors in the cytoplasm or nucleus. This hormonal-receptor complex then interacts with DNA to initiate transcription and ultimately influence gene expression, thereby affecting cellular function. The ability of steroid hormones to traverse the cell membrane distinguishes them from water-soluble hormones, which cannot easily penetrate this barrier and instead rely on membrane receptors to exert their effects.