Signal transduction

Science

Definition

Signal transduction is the process by which a cell converts an external signal (like a hormone or neurotransmitter) into a cellular response. A signaling molecule binds to a receptor, triggering a cascade of molecular events inside the cell that ultimately changes cell behavior.

How It Works

  1. A signaling molecule (ligand) binds to a specific receptor on the cell surface.
  2. The receptor changes shape, activating intracellular relay proteins.
  3. A cascade of phosphorylation events amplifies the signal through the cell.
  4. The amplified signal activates transcription factors or enzymes that produce the cellular response.
  5. The response is terminated when the signaling molecule is removed or degraded.

Examples

  • Adrenaline binding to heart muscle receptors to increase heart rate
  • Insulin binding to receptors triggering glucose uptake into cells
  • Growth factors activating cell division pathways

Related Terms

Cell membrane Gene regulation Enzyme structure Feedback mechanisms

Study This Concept

Practice signal transduction with free review games in these units:

AP Biology Unit 4: Cell Communication and Cell Cycle