Receptors are protein molecules that bind ligand.
There are two types of receptors: internal and cell-surface receptors.
Hydrophobic signaling molecules interact with internal receptors in the cytoplasm.
Internal receptors are transcription factors that regulate gene expression.
Cell-surface receptors are membrane-anchored proteins that bind to external ligand molecules.
Cell-surface receptors have three main components: an external ligand-binding domain, a hydrophobic membrane-spanning region, and an intracellular domain.
There are three general categories of cell-surface receptors: ion channel-linked receptors, G-protein-linked receptors, and enzyme-linked receptors.
G-protein-linked receptors activate a membrane protein called a G-protein.
Enzyme-linked receptors have intracellular domains associated with an enzyme.
Malfunction in receptor proteins can cause diseases such as hypertension, asthma, heart disease, and cancer.

Test your knowledge on the fascinating world of receptors with this quiz! From the different types of receptors to their functions and malfunctions, this quiz covers it all. Explore the differences between internal and cell-surface receptors, learn about the three categories of cell-surface receptors, and discover the role of receptor proteins in diseases like hypertension and cancer. Challenge yourself and enhance your understanding of this crucial aspect of biology with this quiz.