Cell Signaling and Membrane Transport

Flashcards for cell signaling and membrane transport

Passive Transport

Diffusion of a substance across a membrane with no energy investment.

Active Transport

Uses energy to move solutes against their concentration gradients.

Bulk Transport

Transport across the plasma membrane via exocytosis and endocytosis.

Plasma Membrane

Plays a key role in most cell signaling.

Selectively Permeable Membrane

Plasma membrane allows some substances to cross more easily than others.

Facilitated Diffusion

Passive transport aided by proteins.

Channel Proteins

Provide corridors that allow specific molecules or ions to cross the membrane.

Aquaporins

Channel proteins that facilitate diffusion of water.

Ion Channels

Channel proteins that open or close in response to a stimulus (gated channels).

Carrier Proteins

Undergo a subtle change in shape that translocates the solute-binding site across the membrane.

ATP

Energy form usually required for active transport.

Sodium-Potassium Pump

One type of active transport system to maintain concentration gradients.

Membrane Potential

Voltage across a membrane.

Electrochemical Gradient

Two combined forces (chemical and electrical) that drive the diffusion of ions across a membrane.

Electrogenic Pump

Transport protein that generates voltage across a membrane.

Proton Pump

Main electrogenic pump of plants, fungi, and bacteria.

Cotransport

Active transport of a solute indirectly drives transport of other solutes.

Exocytosis

Transport vesicles migrate to the membrane, fuse with it, and release their contents.

Endocytosis

The cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane.

Phagocytosis

Cellular eating.

Pinocytosis

Cellular drinking.

Receptor-mediated Endocytosis

Allows the cell to acquire bulk quantities of specific substances.

Local Regulators

Messenger molecules that travel short distances in local signaling.

Paracrine Signaling

Local signaling in animal cells.

Synaptic Signaling

Specialized type of local signaling in the animal nervous system.

Hormones

Chemicals used in long-distance signaling by plants and animals.

Endocrine Signaling

Hormonal signaling in animals.

Reception

The binding of a signaling molecule to a receptor protein.

Transduction

Relay molecules in a signal transduction pathway.

Response

Cellular activity triggered by a signal.

Ligand

A signal molecule that binds to a receptor.

G Protein-Coupled Receptors (GPCRs)

Plasma membrane receptors that work with the help of a G protein.

Ligand-Gated Ion Channel

Receptor that acts as a gate for ions when the receptor changes shape.

Intracellular Receptor Proteins

Found in the cytosol or nucleus of target cells.

Protein Kinases

Transfer phosphates from ATP to protein, a process called phosphorylation.

Protein Phosphatases

Remove phosphates from proteins, a process called dephosphorylation.

Second Messengers

Small, nonprotein, water-soluble molecules or ions that spread throughout a cell by diffusion.

Cyclic AMP (cAMP)

Widely used second messenger.

Adenylyl Cyclase

Enzyme in the plasma membrane that converts ATP to cAMP.

Transcription Factor

Final activated molecule in the signaling pathway.