Biological Membranes and Transport

This set of flashcards covers key vocabulary related to biological membranes and the processes of transport across them.

Phospholipids

Molecules that make up the bilayer of cell membranes; they are amphipathic, having a hydrophilic head and hydrophobic tails.

Amphipathic

A property of molecules that have both hydrophilic (water-attracting) and hydrophobic (water-repelling) portions.

Fluid Mosaic Model

A model describing the structure of cell membranes as a mosaic of various proteins that float in or on the fluid lipid bilayer.

Cholesterol

A type of lipid that embeds between phospholipid tails in the membrane, helping to stabilize its fluidity.

Transmembrane proteins

Integral proteins that span the membrane and are involved in transport and signaling.

Passive Transport

The movement of substances across a cell membrane without the use of energy; substances move from areas of high concentration to low concentration.

Osmosis

The diffusion of water across a selectively permeable membrane.

Facilitated Diffusion

Process of passive transport where molecules move across a membrane via transport proteins.

Carrier proteins

Proteins that transport large polar molecules, such as sugars, across the membrane via facilitated diffusion.

Active Transport

The movement of substances against their concentration gradient, requiring energy input, often in the form of ATP.

Equilibrium

A state of balance in concentrations of molecules on both sides of a membrane.

Selective permeability

The property of a membrane that allows certain molecules to pass through while blocking others.

Hypotonic solution

A solution with a lower concentration of solutes compared to another solution, causing cells to swell.

Hypertonic solution

A solution with a higher concentration of solutes compared to another solution, causing cells to shrink.

Isotonic solution

A solution where the concentration of solutes is equal to that of another solution, resulting in no net movement of water.

Transmembrane channels

Protein channels that allow specific ions or small polar molecules to pass through the membrane via facilitated diffusion.