CH3 CELL PT 5 - CellTransport Mechanisms Notes -

Vocabulary flashcards covering the key terms and concepts from the cell transport section of the lecture notes.

Plasma membrane

The phospholipid bilayer that encloses the cell, containing integral and transmembrane proteins; it is selectively permeable.

Phospholipid bilayer

Two layers of phospholipids forming the cell membrane with hydrophilic heads facing outward and hydrophobic tails inward.

Selectively permeable

Property of the membrane that allows some substances to pass while restricting others.

Lipid soluble (nonpolar)

Substances that can diffuse directly through the membrane because they are nonpolar.

Water soluble (polar) requiring carrier or channel

Polar substances that require a membrane protein (carrier or channel) to cross the membrane.

Carrier protein

A membrane protein that binds a solute (e.g., glucose) and changes shape to move it across the membrane.

Channel protein

A membrane protein that forms a pore (ion channel) for specific ions to move down their gradient.

Diffusion

Movement of a substance from high to low concentration across the membrane, down a concentration gradient; no ATP required.

Concentration gradient

The difference in solute concentration across a membrane; diffusion proceeds down this gradient.

Facilitated diffusion

Passive transport of polar or charged solutes through carrier or channel proteins down a gradient; no ATP used.

Osmosis

Movement of water across a semipermeable membrane toward higher solute concentration.

Aquaporin

Water channel protein in the membrane that enables rapid water movement.

Isotonic

A solution with the same solute concentration as the cell, producing no net water movement.

Hypotonic

A solution with lower solute concentration (more water) than the cell; water enters the cell.

Hypertonic

A solution with higher solute concentration (less water) than the cell; water leaves the cell.

Hemolysis

RBC rupture due to excessive hypotonic solution causing over-inflow of water.

Crenation

RBC shrinkage due to a hypertonic solution drawing water out of the cell.

Normal saline (0.9% NaCl)

An isotonic IV fluid that preserves cell shape by matching intracellular solute concentration.

5% glucose solution

An isotonic IV solution used to deliver glucose without osmotically altering cells.

Passive transport

Transport across the membrane that does not require ATP; includes diffusion, facilitated diffusion, osmosis.

Active transport

Transport that requires ATP; moves substances against their concentration gradient.

Sodium-potassium pump (Na+/K+ ATPase)

Membrane pump using ATP to move 3 Na+ out and 2 K+ in, maintaining gradient essential for cell function.

Endocytosis

Process of taking substances into the cell via vesicle formation; ATP-dependent; vesicular transport.

Receptor-mediated endocytosis

Endocytosis initiated when a ligand binds to a specific cell-surface receptor, triggering uptake.

Phagocytosis

Endocytosis of solids (e.g., bacteria) often by white blood cells surrounding the particle.

Pinocytosis

Endocytosis of fluids; cell drinking.

Exocytosis

Process of exporting substances out of the cell via vesicle fusion with the plasma membrane; ATP-dependent.

Vesicular transport

Movement of materials in membrane-bound vesicles; includes endocytosis and exocytosis.

Lysosome

Digestive organelle that fuses with endocytic vesicles to degrade their contents.

Secretory vesicle

Vesicle carrying proteins from the Golgi that is released by exocytosis.

Golgi apparatus

Organelle that modifies, sorts, and packages proteins received from the ER.

Rough endoplasmic reticulum

ER studded with ribosomes where protein synthesis occurs and vesicles are formed.