Plasma Membrane and Transport Vocabulary

Vocabulary flashcards covering key terms related to the plasma membrane, its components, and transport mechanisms.

Plasma Membrane

Selectively permeable boundary of the cell that controls what goes in and out. Allows cell to communicate with ou

Selectively Permeable

Property of membranes that allows some molecules to pass while restricting others.

Phospholipid

Amphipathic lipid with glycerol, a phosphate group, and two fatty acids; main component of cellular membranes.

Amphipathic

Having both hydrophilic (water-loving) and hydrophobic (water-fearing) regions in the same molecule.

Hydrophilic Head

Polar glycerol-phosphate portion of a phospholipid that faces aqueous environments.

Hydrophobic Tail

Non-polar fatty-acid chains of a phospholipid that avoid water and face inward.

Phospholipid Bilayer

Double layer of phospholipids with heads outward and tails inward, forming the basic membrane structure.

Fluid Mosaic Model

Describes membranes as fluid things move around.

As a mosaic contains many different types of components. Protein, lipids, cholesterol and carbohydrates

Cholesterol

Hydrophobic molecule in animal membranes that stiffens the bilayer and reduces permeability.

Transport Protein

Membrane protein that regulates the movement of specific molecules across the membrane.

Channel Protein

Tunnel-like transport protein permitting passage based on size and charge.

Carrier Protein

Transport protein that binds a specific molecule and changes shape to move it across the membrane.

Recognition Protein (Glycoprotein)

Protein with attached sugars that allow cells to identify and interact with each other.

Receptor Protein

Membrane protein that binds signaling molecules and triggers cellular responses.

Membrane Permeability

Capacity of the membrane to allow substances to enter or exit the cell.

Simple Diffusion

Movement of molecules from high to low concentration directly through the bilayer without energy or proteins. Smaller hydrophobic molecules like co2 h2o, n2 benzene

Concentration Gradient

Difference in the amount of a substance across space or a membrane.

Passive Transport

Movement across a membrane that requires no energy (includes diffusion, osmosis, facilitated diffusion).

Osmosis

Diffusion of water across a selectively permeable membrane from high to low water concentration.

Isotonic

Condition where two solutions have equal solute concentrations, resulting in no net water movement.

Hypertonic

Solution with a higher solute concentration that pulls water toward it.

Hypotonic

Solution with a lower solute concentration that loses water to a hypertonic environment.

Turgid

Swollen, firm condition of a plant cell in a hypotonic environment.

Flaccid

Limp condition of a plant cell in a hypertonic environment.

Facilitated Diffusion

Passive movement of molecules down their gradient via a channel or carrier protein.

Active Transport

Energy-requiring process that pumps molecules against their concentration gradient using transport proteins.

ATP (Adenosine Triphosphate)

Primary energy currency of the cell; supplies energy for active transport (ATP → ADP + Pi).

Semipermeable Membrane

Membrane that allows certain molecules to pass while blocking others; synonymous with selectively permeable.