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