Cellular Transport

How cells interact with the outside worldChapter 7-3

Pgs. 184 - 189

• Movement WITH the concentration gradient• Stuff moves from high to low concentration

• occurs until equilibrium is reached

BOOSH! Equilibrium

Getting across a cell membrane

• Passive transport – Simple diffusion– Osmosis– Facilitated diffusion

• Active transport

• Can Semi Permeable barriers really exist?

• Can a barrier really be choosy about what it does and doesn’t let through?

1. Did the Iodine interact with the Cornstarch?

2. Will the water move in or out of the bag

3. Did the cornstarch move with it?

4. What is this bag permeable to?

5. What does this bag select against?

Simple Diffusion

DIFFUSION

HIGH to LOW concentration

Simple diffusion

• Small, non-polar molecules without a charge can squeeze through the cell membrane without the help of protein channels.

• Flows with the concentration gradient

• movement of larger molecules like glucose through the cell membrane – larger molecules must be “helped”

• Proteins in the cell membrane form channels for large molecules to pass through

• Proteins that form channels (pores) are called protein channels

outside of cell

inside of cell

Glucose molecules

Facilitated Diffusion

http://www.northland.cc.mn.us/biology/biology1111/animations/passive3.swf

Facilitated Diffusion

H2OCell Membrane

Protein Channel(aquaporin)

Osmosis

Osmosis

• water Diffuses across a membrane

Osmosis is not simple diffusion

• H2O moves through special protein channels

Na+

Cl-

refers to a solution with a comparatively lower concentration of solutes compared to another

Active tranport

• Using cellular energy in the form of ATP to move particles across the cell membrane

• Moves against the concentration gradient

ATP

Cellular Currency• If you want to get something done in the cell you need to spend a little ATP

Active transport

• Intake of large molecules or large quantities of molecules by surrounding them with the cell membrane

Endocytosis

Exocytosis

Vesicles

Three types of Endocytosis

Cell Eating Cell Drinking Targeted endocytosis

ANIMATION TIME