Diffusion and the Cell Membrane

I. Diffusion http://www.youtube.com/watch?v

=Vzwh4hSHS7s

A. Energy- all particles are moving all the time.

B. Diffusion – particles spread out from areas of high concentration to areas of lower concentration until spread evenly.

C. Dynamic Equilibrium – eventually, particles are evenly spread (but still moving)

Why do smells go away?

Do oil and water mix?Why or why not?

II. Phospholipids – Make up the _________ ________ (or the Cell membrane)

III. Lipid Bilayer around a Cell

IV. Diffusion and the Cell Membrane

• How do O2, H2O, and Sugar get into a cell?

• How do cells recognize foreign invaders?

A. Passive Transport1. _______________ ______________ - smaller particles like _____________ can simply slide into a cell through the _______________ of the __________ from a ______________ to a ______________ concentration.

Simple Diffusion Oxygen (O2)

lipid bilayer phospholipids

lowerhigher

2. _______________ ______________ - larger particles like ______________ can diffuse from a ________________ to a _______________ concentration, but they need doors called ____________ _______________.

*** Since both simple diffusion and facilitated diffusion require no ___________ , they are referred to as _____________ transport.passive

energy

protein channels

Facilitated Diffusion sugar

higher lower

B. Active Transport (actually, it’s the opposite of diffusion)

• Sometimes a cell needs to move particles against a concentration gradient from a _____________ to a ______________ concentration.

lowerhigher

• For example, bone cells have a lot of _____________ in them. To grow and stay healthy these cells need to _________ calcium from outside to inside the cell. Since the particles must be pushed against the ______________ _____________ from a lower to a ____________ concentration, _________ must be used with special protein channels that “__________” the calcium ions into a cell.

calcium

concentrationgradient

higherenergy

pump

push

• *** Since this process requires ____________ and the movement of particles in the opposite direction of diffusion, it is called _____________ transport.

energy

active

Active vs. Passive Transport

V. Carbohydrate Chains • They are like ___ ______

for the cells. ________ float around your body looking at the ________________ ________ of cells, looking for ______________. If an invader is found, the ______ will ___________ the invader and break it apart with _______________.

ID cardsWhite blood cells

carbohydrate chains

foreign invaders

WBC engulf

its lysosomes