Biological Membranes and Transport

Flashcards covering key vocabulary related to biological membranes, diffusion, and osmosis.

Biological Membrane

Consists of a phospholipid bilayer with transmembrane and surface proteins.

Selective Permeability

Allows only certain substances to move easily into or out of the cell.

Diffusion

The movement of substances from a region of higher concentration to one of lower concentration.

Passive Transport

Transport that occurs without the use of cellular energy (ATP).

Rate of Diffusion Factors

Temperature, size of the substance, and concentration.

Osmosis

The movement of water only across a membrane.

Simple Diffusion

Biological membrane presents no barrier to substances moving in or out of it.

Facilitated Diffusion

Carrier proteins help transport the substance in or out of the biological membrane.

Percent Solution Calculation

% solute + % solvent = 100%

Isotonic Solution

No net water movement.

Hypotonic Solution

Net water movement into the cell.

Hypertonic Solution

Net water movement out of the cell.

Dialysis Bag Experiment

Involves monitoring the weight change of a bag containing 20% sucrose in an unknown solution.

Transmembrane Proteins

Proteins embedded within the phospholipid bilayer of a biological membrane.

Surface Proteins

Proteins located on the surface of a biological membrane.

Concentration Gradient

The difference in concentration of a substance across a space.

Solute

The substance that is dissolved in a solution.

Solvent

The substance in which a solute is dissolved.

ATP

Adenosine Triphosphate; a molecule that carries energy within cells.

Carrier Proteins

Proteins that facilitate the movement of substances across a biological membrane.

Tonicity

The relative concentration of solutes in two solutions separated by a semipermeable membrane

Hypothesis

A testable explanation for a phenomenon

Semipermeable Membrane

A membrane (as a cell membrane) that allows some molecules to pass through but not others

Equilibrium

A state of balance

Phospholipid bilayer

A double layer of phospholipids that makes up plasma and organelle membranes.