Name:______Period:______

Notes:

TRANSPORT THROUGH CELL MEMBRANES

Cells are surrounded by a semi-permeable membrane which allows some materials to enter and exit the cell.

Only materials that are dissolved in a solution can be transported across the cell membrane.

METHODS OF CELL TRANSPORT

__Diffusion/Osmosis______

__Facilitated diffusion______

__Active Transport: endocytosisexocytosis______

DIFFUSION

The movement of molecules from an area of high concentration to an area of lowconcentration.

Concentration: The number of molecules of a substance in a given volume.

High concentration: More molecules of solute

Low concentration: Less molecules of solute

Solute: Substance that dissolves in the liquid

Solvent: Liquid part in a solution

Concentration: amount of a solute in a given solution

The molecules have natural random motion , which they use to move from one area to another.

Molecules continue to move until they reach equilibrium

When the molecules have spread out _evenly__ the solution is said to be in equilibrium.

DIFFUSIN ACROSS THE CELL MEMBRANE

The cell membrane is made up of two layers of lipids and proteins.

There are openings called __Pores___ in the cell membrane.

DIFFUSION CAN OCCUR ONLY IF:

The concentration on one side of the cell is _higher____ and the concentration on the other side is _lower_____

Molecules must be __smaller____ than the pores in the cell membrane

Diffusion is passive: The cell does not use its own energy to move the molecules.

OSMOSIS:

The diffusion on ONLY __water___ molecules.

Water moves from an area of _high__ concentration to an area of _lower___ concentration.

A cell will___burst______if too much water enters

The cell will__shrink_____ if too much water leaves.

Dilute solution: very _high___ number of water molecules, low number of solute molecules.

Concentrated solution: very low number of ___water molecules._

  1. Passive Transport:

No energy required

Ex: Diffusion, Osmosis and facilitated diffusion

Facilitated diffusion: Movement of molecules across a semi-permeable membrane with a _transport proteins___. Used to move large molecules

  1. Active Transport:

The movement of substances across a cell membrane using _energy___

Move substances from _Low____ to __hign___ concentration

Endocytosis: molecules __enters______the cell.

Exocytosis: molecules __exit____ the cell.