Video from Youtube on Diffusion and osmosis – www.youtube.com/watch?v=AYNwynwaALo

Homeostasis Steady stateBalance an organism maintains by self

regulating adjustmentsExample: Body Temperature and Heart Rate

(blood Flow supply o2 and nutrients)

DIFFUSION

Process by which molecules spread due to their random movement from an area of high concentration to low concentration

Example: when you spray lysol

CONCENTRATION GRADIENTDifference in concentration of a substance in

a given area

MOLECULES move naturally from high concentration to low concentration until equilibrium is reached.

Equilibrium means balance or homeostasis

Three Ways to increase rate of diffusion: concentrationincrease pressureHeat (makes molecules move faster)

Cell Membrane – regulate molecules – the flow of materials in and out of the cell

Permeable – if substance passes through it is permeable to that substance

Selectively permeable – only allows some substance through

Solution – a mixture of one or more substances dissolved in it

Solvent – waterSolute – salt Idea: kool aid – water is the solvent and the

packet of mix is the solute

THREE TYPES OF SOLUTIONS:Hypotonic solution – concentration of solutes

in the environment lower than in the cell (H2O moves in)

Hypertonic – concentration of solutes in the environment is higher than in cell (H2O moves out)

Isotonic solution – equal concentration of solute in cell and environment ( h20 in and out equally) Maintains equilibrium or homeostasis

Type of Solutions

If the concentration of solute (salt) is equal on both sides, the water will move back in forth but it won't have any result on the overall amount of water on either side."ISO" means the same

The word "HYPO" means less, in this case there are less solute (salt) molecules outside the cell, since salt sucks, water will move into the cell.The cell will gain water and grow larger. In plant cells, the central vacuoles will fill and the plant becomes stiff and rigid, the cell wall keeps the plant from burstingIn animal cells, the cell may be in danger of bursting, organelles called CONTRACTILE VACUOLES will pump water out of the cell to prevent this.

The word "HYPER" means more, in this case there are more solute (salt) molecules outside the cell, which causes the water to be sucked in that direction.In plant cells, the central vacuole loses water and the cells shrink, causing wilting.In animal cells, the cells also shrink.In both cases, the cell may die.This is why it is dangerous to drink sea water - its a myth that drinking sea water will cause you to go insane, but people marooned at sea will speed up dehydration (and death) by drinking sea water. This is also why "salting fields" was a common tactic during war, it would kill the crops in the field, thus causing food shortages.

Type of Solutions                                                                                              

Isotonic Solution – equal concentration of solute in cell and environment (H2O in and out equally)

Osmosis – diffusion of water from areas of greater concentration to lesser concentration

Turgor pressure – as water diffuses into a plant cell it exerts a force against the cell wall

Plasmolysis – cell shrink

Cytolysis – cell bursts

Contractile vacuole – some single cell animals in the water use this to pump out the excess water

Passive transport – movement across a membrane without use of energy (Diffusion and Osmosis)

Active Transport – movement across a membrane with energy

Carrier Molecule – proteins which function in transport

a.Facilitate diffusion – uses a carrier molecule to speed up diffusion but does not use energy

Example: Glucose needs insulin to speed diffusion into cell

b.Active transport – uses carrier molecules to go against concentration gradient. Uses energy.

MOVEMENT OF LARGE MOLECULESEndocytosis (endo – in)process by which cells

engulf substances which are too large to diffuse through the cell membrane

a.Phagocytosis – foodb.Pinocytosis – liquid

Example: ameba white blood cells

Exocytosis ( exo-out) movement of large molecules out of the cell

Example: wastes

Active and Passive Transportvideo on transport and endocytosisi

Review of Terms:A difference in concentration creates a concentration

gradientPrefix that means “inside” is endoA word that means “cell” – cytoPrefix that means “outside” – exoActive transport will remove sodium ions, while taking

in potassium ionsChannel proteins can help move things across the

membraneOrganelle that helps remove excess water; contractile

vacuoleThe outer boundary of the cell is the membrane