CHAPTER 8.1 IN CLASS NOTES CELLULAR TRANSPORT

Ask yourself this question Fact: All things in water are dissolved  Such as Salt (NaCl) Fact: Dissolved particles (salt) will always move from high to low concentrations if on opposite sides of a plasma membrane (diffusion)

Ask yourself this question Fact: In the picture below, there is two things on each side of the membrane. Water and Salt. Question: If you wanted to get them equal on both sides, rather than just waiting for the salt to move, what could occur that would speed up the process?

I. OSMOSIS: THE DIFFUSION OF WATER Osmosis: the diffusion of WATER across a selectively permeable membrane  used, like regular diffusion, to maintain homeostasis within a cell A. What controls Diffusion? The presence of a concentration gradient (high to low) The type of solution you put a cell in controls osmosis

Osmosis

I. OSMOSIS: THE DIFFUSION OF WATER A. What controls Diffusion? Three types of solutions are:  1. Isotonic solution: concentration of dissolved substances is equal throughout and there will be NO movement of H2O  2. HypOtonic solution: concentration of dissolved substances is greater inside than outside. Water moves into the cell causing it to swell or become Oversized  3. HypeRtonic solution: concentration of dissolved substance is greater outside than inside. Water will move out of the cell causing it to shRink or shRivel up.

Hypotonic, Isotonic, and Hypertonic

II. PASSIVE TRANSPORT Passive transport: movement across plasma membrane that requires NO ENERGY  ex: diffusion and osmosis are both passive  Movement from high to low  Like gravity A. Passive Transport by Proteins Facilitated diffusion: passive transport of materials across plasma membrane using “transport/membrane/carrier/channel” proteins  goes WITH concentration gradient and requires NO energy

III. ACTIVE TRANSPORT Active transport: movement of material across plasma membrane AGAINST the concentration gradient  REQUIRES ENERGY A. How Active Transport Occurs “carrier” proteins primarily used here  These proteins bind and change shape to move particles against the concentration gradient

Active vs. Passive Transport

IV. TRANSPORT OF LARGE PARTICLES Endocytosis: process by which a cell surrounds and engulfs (takes in/”ingests”) material from it’s environment Exocytosis: the expulsion or excretion (egestion) of materials from a cell  Hormones are excreted from cells using this process BOTH PROCESSES require energy from the cell since particles are so large

Exocytosis vs. Endocytosis