1. The Cell in its Environment

2. Diffusion
The movement of particles from an area of high concentration to an area of low concentration
Requires no energy!

3. Selectively Permeable
The cell membrane is selectively permeable, which means some substances can pass through the membrane while others cannot.
(CELL MEMBRANE – SELECTS WHAT GOES IN AND OUT OF THE CELL)

4. Osmosis
Diffusion of water (tiny, no charge) across the cell membrane (a selectively permeable membrane) from high concentration to low.
No energy required!

6. 2 Types of cell transport
PASSIVE TRANSPORT
NO ENERGY REQUIRED
DIFFUSION AND OSMOSIS
MOVEMENT FROM HIGH TO LOW CONCENTRATION
ACTIVE TRANSPORT
ENERGY REQUIRED
MOVEMENT FROM LOW TO HIGH CONCENTRATION
Transfer Proteins – Proteins “pick up” molecules and carry them into and out of the cell using energy!!
Transfer by Engulfing – The cell membrane surrounds and engulfs or encloses a particle.

7. In receptor-mediated endocytosis, coated pits form vesicles when specific molecules bind to receptors on the cell surface. Notice that there is a greater relative number of bound molecules (purple) inside the vesicles.