Final answer:
Steroid hormones take longer to show effects because they alter gene expression by directly interacting with intracellular receptors and DNA within the cell. This process is less immediate than the action of peptide hormones, which bind to cell surface receptors and trigger faster second messenger pathways.
Step-by-step explanation:
The effects of steroid hormones take longer than peptide hormones because steroid hormones alter gene expression (c). Unlike peptide hormones that bind to cell surface receptors and act through second messengers, steroid hormones cross the cell membrane and nuclear envelope to bind with intracellular receptors and directly regulate the transcription of genes. This process of altering gene expression is generally slower than the mechanism of peptide hormones, which is why the responses to steroid hormones usually take longer.
Steroid hormones are hydrophobic and can readily pass through the cell membrane. They bind to receptors either in the cytoplasm or the nucleus and then interact with DNA to regulate gene expression, affecting the synthesis of mRNA and proteins. These changes are often more sustained than the rapid and transient responses elicited by peptide hormones.
By comparison, peptide and amino acid-derived hormones are water-soluble, cannot cross the lipid bilayer of cell membranes, and therefore bind to hormone receptors on the cell surface initiating intracellular signaling cascades, often involving second messengers such as cAMP.