Membranes and Transport Lecture Notes

Vocabulary flashcards covering membrane structure, components, and transport mechanisms based on the lecture notes.

Fluid Mosaic Model

A structural model describing the membrane as a mosaic of various proteins that can move laterally within a fluid bilayer of phospholipids.

Phospholipids

The primary components of the membrane, containing a hydrophilic head (choline, phosphate, and glycerol) and hydrophobic tails (fatty acids).

Amphipathic

The nature of phospholipids and some proteins having both a hydrophilic region and a hydrophobic region.

Integral protein

Proteins that are often transmembrane, meaning they span across the membrane.

Peripheral proteins

Proteins that are located on the surface of the membrane rather than spanning through it.

Glycoprotein

A polysaccharide attached to a protein, primarily used for cell identification.

Glycolipid

A polysaccharide attached to a lipid, primarily used for cell identification.

Selective permeability

A characteristic of the plasma membrane that allows certain substances to cross more easily than others.

Passive Transport

Movement of substances across the membrane down their concentration gradient without the use of metabolic energy ($ATP$).

Active Transport

Movement of substances against their concentration gradient through a carrier protein, requiring metabolic energy ($ATP$).

Diffusion

The tendency for molecules of a substance to fill available space due to constant random motion until they are evenly distributed.

Dynamic Equilibrium

A state in which there is no net movement of substances after diffusing evenly across a space.

Osmosis

A special case of diffusion involving the movement of water across a selectively permeable membrane.

Solvent

A substance capable of dissolving other substances.

Solute

A substance that is dissolved within a solvent.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water.

Isotonic

A solution where the solute concentration outside the cell equals the solute concentration inside the cell, resulting in no net water movement.

Hypertonic

A solution where the solute concentration outside the cell is greater than the concentration inside the cell, causing the cell to lose $H_2O$.

Hypotonic

A solution where the solute concentration outside the cell is less than the concentration inside the cell, causing the cell to gain $H_2O$.

Facilitated Diffusion

Passive transport of specific molecules across a membrane through transport proteins, categorized as channel or carrier proteins.

Sodium-Potassium Pump

An active transport mechanism that moves $3\,Na^+$ out of the cell and $2\,K^+$ into the cell to establish an electrical gradient.

Van der Waals interactions

The hydrophobic interactions that help hold the phospholipid bilayer together spontaneously.