crossing the cell membrane osmosis active transport passive transport diffusion endo/exo - cytosis

Crossing the Cell Membrane

OsmosisActive Transport

Passive transport DiffusionEndo/Exo - Cytosis

Warm Up Questions:

1. All _______________ are composed of cells.

2. New cells are produced from _________________.

3. What is the main purpose of the cell membrane?

4. What are some examples of manmade membranes? (Try to think of at least two.)

Cell Membranes

Made up of a lipid bi-layer

Selectively Permeable: Not all particles can pass through the membrane without help from special membrane proteins

Active Transport

The process by which proteins on the cell membrane push particles from one side of the membrane to the other

Requires energy (ATP)

Occurs when particles are two large to diffuse through a membrane or;

Occurs when particles are moving against the forces of diffusion (Particles are moving from an area of low concentration to an area of high concentration)

Active Transport

H2O

H2O

H2O

H2O

H2O

H2O

H2O

H2O

H2O

H2O

H2O

A B

Na+

Na+

Na+

Na+

Active Transport

Active Transport

Passive Transport

Normal Diffusion that requires membrane proteins Channel ProteinsCarrier Proteins

EndocytosisEndocytosis is the process by which nutrients are

engulfed by the cell membrane

ExocytosisThe process by which a vesicle inside the cell

fuses with the cell membrane and expels its contents outside the cell