BackMembrane Transport and Cell Signaling
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Terms in this set (21)
Membrane transport is the movement of substances across a cell membrane, essential for maintaining homeostasis.
Passive transport requires no energy and moves substances down their concentration gradient; active transport requires energy to move substances against their gradient.
Diffusion is the passive movement of molecules from an area of higher concentration to lower concentration.
Osmosis is the diffusion of water across a selectively permeable membrane from low to high solute concentration.
Channel proteins form pores in membranes allowing specific molecules or ions to passively diffuse through.
Carrier proteins bind to specific molecules and change shape to transport them across the membrane.
Facilitated diffusion is passive transport aided by carrier or channel proteins without energy use.
Active transport uses energy, often ATP, to move substances against their concentration gradient via transport proteins.
The sodium-potassium pump is an active transport protein that moves 3 Na+ out and 2 K+ into the cell using ATP.
Endocytosis is the process where cells engulf external substances by enclosing them in a vesicle.
Exocytosis is the process of vesicles fusing with the plasma membrane to release contents outside the cell.
Receptor-mediated endocytosis is a selective form of endocytosis where specific molecules bind to receptors before vesicle formation.
Cell signaling is the process by which cells communicate and respond to external signals.
Includes autocrine, paracrine, endocrine, and direct contact signaling.
A ligand is a molecule that binds specifically to a receptor to trigger a cellular response.
Membrane receptors detect extracellular signals and initiate intracellular responses.
Signal transduction is the process of converting a signal from outside the cell into a functional response inside the cell.
A second messenger is a small molecule that relays signals from receptors to target molecules inside the cell.
cAMP (cyclic adenosine monophosphate) is a common second messenger in many signaling pathways.
G-protein coupled receptors activate intracellular G-proteins upon ligand binding to trigger signaling cascades.
Phosphorylation is the addition of a phosphate group to proteins, often regulating their activity in signaling pathways.