Cell MembranesOsmosis and Diffusion

PREFIX – SUFFIX ADDITIONS Hypo – under, beneath, lacking Hyper – over, above, excess Iso – equal Tonic – stretching, tone

Functions of Membranes

1. Protect cell2. Control incoming and outgoing

substances3. Maintain ion concentrations of various

substances

4. FLASH CARD ALERT!!! 4. SELECTIVELY PERMEABLE - allows some

molecules in, others are kept out

Phospholipid Bilayer

Fluid Mosaic Model

SolutionsSolutions are made of solute and a

solvent

FLASH CARD ALERT!!!! SOLVENT - the liquid into which the

solute is poured and dissolved. We will use water as our solvent in Lab #4

SOLUTE - substance that is dissolved or put into the solvent. Salt and sucrose are solutes.

Methods of Transport Across Membranes1. Diffusion

2. Osmosis

3. Facilitated Diffusion

4. Active Transport

FLASH CARD ALERT!!! 1. DIFFUSION -passive transport of

molecules - no energy expended2. OSMOSIS - Passive transport of WATER

across membrane3. FACILITATED DIFFUSION- Use of

carrier proteins to carry polar molecules or ions across membrane

4. ACTIVE TRANSPORT requires energy to transport molecules AGAINST A CONCENTRATION GRADIENT. energy is in the form of ATP

Where does that ATP come from?

DiffusionMovement of molecules from an area

of high concentration to an area of low concentration.

DIFFUSION = MOVEMENT OF MOLECULES

OSMOSIS = MOVEMENT OF

WATER.

Diffusion

Facilitated Diffusion

Passive – Does not require energy Uses carrier proteins

Molecules combine with carrier proteins. These molecules speed up the passage over the membrane.

Glucose

Osmosis

Tonicity is a relative termFLASH CARD ALERT!!! Hypotonic Solution - One solution has a lower concentration of solute than another.

Hypertonic Solution - one solution has a higher concentration of solute than another.

Isotonic Solution - both solutions have same concentrations of solute.

Plant and Animal Cells put into various solutions

Carrier Proteins CARRIER PROTEINS –

bind to a specific type of diffusing molecule. They have a highly specific hydrophilic region to which the solute molecule binds. This binding cause the protein to undergo a change in shape that moves the solute across the bilayer and release it on the other side

Active Transport Active transport is

the transport of molecules by carrier proteins AGAINST a concentration gradient.

REQUIRES ENERGY IN THE FORM OF ATP

Types of Transport

http://www.youtube.com/watch?v=sdiJtDRJQEc&safety_mode=true&persist_safety_mode=1&safe=active