Cell Membranes and Lipid Structures

Cell Membrane

Cell Membrane

Selective barrier separating life from nonlife.

Lipid

Carbon-containing compounds insoluble in water.

Fatty Acid

Hydrocarbon chain bonded to a polar carboxyl group.

Saturated Fatty Acid

Only single bonds between carbon atoms.

Unsaturated Fatty Acid

Contains one or more double bonds.

Polyunsaturated Fatty Acid

Has multiple double bonds in hydrocarbon chain.

Hydrogenation

Process converting unsaturated fats to saturated fats.

Steroid

Lipids with a bulky four-ring structure.

Triglyceride

Three fatty acids linked to glycerol.

Phospholipid

Glycerol linked to phosphate group and fatty acids.

Amphipathic

Molecule with both hydrophilic and hydrophobic regions.

Hydrophobic Effect

Clustering of hydrophobic molecules in water.

Phospholipid Bilayer

Two-layer structure forming cell membranes.

Selective Permeability

Ability of membranes to control substance passage.

Diffusion

Spontaneous movement of molecules from high to low concentration.

Osmosis

Diffusion of water across a selectively permeable membrane.

Hypertonic Solution

Higher solute concentration outside the cell.

Hypotonic Solution

Lower solute concentration outside the cell.

Isotonic Solution

Equal solute concentration inside and outside the cell.

Membrane Fluidity

Movement of lipids and proteins within the bilayer.

Cholesterol

Increases membrane density and reduces permeability.

Concentration Gradient

Difference in solute concentrations across a membrane.

Equilibrium

Equal distribution of molecules in a solution.

Passive Transport

Movement across membrane without energy input.

Entropy

Measure of disorder in a system.

Lateral Movement

Movement of lipids within the membrane bilayer.

Kink in Hydrocarbon Chain

Caused by double bonds, affecting fluidity.

Artificial Membranes

Planar bilayers used for experimental studies.

Liposome

Artificial vesicle formed from phospholipids in water.