Cell Communication & Signaling – Vocabulary Review

29 vocabulary flashcards covering key terminology from the lecture on cellular communication and signaling.

Cell Communication

The process by which cells detect, interpret, and respond to chemical or physical signals to regulate functions and maintain homeostasis.

Homeostasis

Maintenance of a stable internal environment within an organism despite external changes.

Chemical Signaling

Cell-to-cell communication mediated by secreted molecules (signals) that bind receptors on target cells.

Paracrine Signaling

Local chemical signaling in which a cell releases a molecule that acts on nearby neighboring cells.

Autocrine Signaling

Local signaling in which a cell secretes a molecule that binds receptors on the same cell that released it.

Hormonal Signaling

Long-distance chemical signaling where hormones travel through the bloodstream to reach any cell with appropriate receptors.

Neurotransmitter Signaling

A neuron releases a chemical messenger across a synapse to stimulate an adjacent target cell.

Ligand

A signaling molecule that specifically binds to a receptor to initiate a cellular response.

Receptor

Protein (extracellular or intracellular) that recognizes and binds a ligand, triggering signal transduction.

Target Cell

Cell that possesses receptors for a specific ligand and is capable of responding to it.

Signal Transduction

The intracellular cascade of molecular events that converts an extracellular signal into a specific cellular response.

Extracellular Receptor

Receptor protein embedded in the plasma membrane that binds ligands outside the cell.

Intracellular Receptor

Receptor located within the cytoplasm or nucleus that binds lipid-soluble ligands able to cross the membrane.

Ligand-Gated Ion Channel

Membrane receptor that doubles as an ion channel; opens or closes when a ligand binds.

Catalytic Receptor

Membrane receptor possessing intrinsic enzymatic activity, typically activating enzymatic reactions upon ligand binding.

G-Protein Coupled Receptor (GPCR)

Membrane receptor that activates heterotrimeric G-proteins, initiating downstream signaling cascades.

Signal Amplification

Process in which one ligand-receptor event triggers the activation of many downstream molecules, greatly expanding the signal.

First Messenger

The extracellular ligand that initiates a signaling pathway by binding to its receptor.

Second Messenger

Small intracellular molecule generated or released in response to receptor activation that propagates the signal inside the cell.

cAMP (Cyclic Adenosine Monophosphate)

A second messenger produced by adenylyl cyclase that activates protein kinases within the cell.

Adenylyl Cyclase

Enzyme activated by G-proteins that converts ATP into the second messenger cAMP.

Phospholipase C (PLC)

Enzyme activated by G-proteins that cleaves membrane phospholipids to generate IP3 and DAG.

IP3 (Inositol 1,4,5-trisphosphate)

Second messenger produced by PLC that mobilizes Ca²⁺ from intracellular stores.

Calcium (Ca²⁺) as Second Messenger

Ion released into the cytosol that, upon binding calmodulin or other proteins, drives cellular responses.

Calmodulin

Calcium-binding protein that, once activated by Ca²⁺, modifies and activates various target proteins.

Hormone-Receptor Complex

Association of a lipophilic hormone with its intracellular receptor that can bind DNA to alter gene transcription.

Direct Gene Activation

Signaling mechanism in which an intracellular hormone-receptor complex directly binds DNA to regulate transcription.

Steroid Hormone

Lipid-soluble hormone (e.g., cortisol) that diffuses through the plasma membrane to bind intracellular receptors and modulate gene expression.