Diffusion, Osmosis and Active Transport

Diffusion

The movement of molecules (matter) from an area of greater concentration (how much of something) to an area of lower concentration. Does not require energy.

Osmosis

The movement of water across a semi-permeable membrane through diffusion. (semi-permeable means lets some things in and not others)

Passive Transport

Does NOT require energy....the movement of molecules (matter) from an area of high concentration to an area of low concentration. Diffusion is a kind of passive transport.

Equilibrium

A system in which things become equal; all particles (molecules or matter) become equal

Cell Membrane

Double layer of phospholipids. Holds everything in. Decides what can enter or leave the cell.

Selectively Permeable

Selective= pick and choose
Permeable= things can pass through
The cell membrane is said to be selectively permeable because it allows certain things to pass through and prevents other things from passing through.

Active Transport

The movement of substances into/out of cell through the membrane, against the concentration gradient (from low to high). Requires ATP.

Membrane proteins

Proteins that sit in the membrane and do the work of the membrane, such as Recognition, Receptors, and Transporters

semi-permeable

A membrane that allows only certain things to pass through

solute

Substance dissolved in a solution

solvent

Substance in which something is dissolved - often WATER

Surface area

The amount of surface of the object that touches the outside world

receptor

Protein that detects a signal molecule and performs an action in response.

concentration gradient

Difference in concentration of a substance from one place to another.

isotonic

Solution that has an equal concentration of solutes as another solution.

hypertonic

Solution that has a higher concentration of solutes as another solution.

hypotonic

Solution that has a lower concentration of solutes as another solution.

Starch

Storage form of glucose in plants
A complex carbohydrate found in potatoes, rice, corn, and many other vegetables

Glucose

A simple sugar that is an important source of energy.