Cellular Transport

I. General A. Definition = molecules moving across the cell membrane B. Cell Membrane is selectively permeable (lets some things in, some things out, but not everything)

Cell Membrane

C. Two Main Types of Transport 1. Passive Transport 2. Active Transport

1. Passive Transport a. Requires no energy b. Caused by random movement of molecules c. Molecules move with the concentration gradient

Concentration Gradient = difference in the concentration of a substance across a space

c. Examples of Passive Transport i. Diffusion = process by which molecules move from areas of high concentration to areas of low concentration until equilibrium is reached

Diffusion

Equilibrium = balance of molecules on both sides of membrane ?s 1-5

c. Examples of Passive Transport ii. Osmosis = diffusion of water iii. Ion Channels = charged molecules moved across membrane by proteins

c. Examples of Passive Transport iv. Facilitated Diffusion molecules moved across membrane by carrier proteins ?s 6-10

2. Active Transport a. Requires Energy (ATP) b. Molecules move from areas of low concentration to areas of high concentration c. Molecules move against the concentration gradient

c. Examples of Active Transport i.Carrier Protein Pumps ii. Movement of molecules by vesicles

i. Carrier Protein Pumps E.g. Sodium/Potassium Pump - Ion exchange - Na + moved out / K + moved in - K + moved out / Na + moved in

ii. Movement by vesicles Vesicles form Move molecules across the membrane

ii. Movement by vesicles Endocytosis - into a cell

ii. Movement by vesicles Exocytosis – out of a cell

Passive vs. Active Transport ?s 11-14