1. Bell ringer: Tuesday September 19
What is the difference between passive and active transport?

3. Homeostasis
The need of an organism to maintain and regulate constant or stable internal conditions.
How does your body regulate (aka maintain homeostasis)?
Temperature, pH, and the concentration of other materials and nutrients must be maintained within a relatively narrow margin.
Much of homeostasis is maintained by the cell membrane controlling movement of things in and out of the cell

4. Cell Membrane
The cell membrane is said to be selectively permeable, meaning certain substances can move across it freely, while others must move through a “gate”.
Transport of materials can be classified as either passive transport or active transport.

5. Cellular Transport
Passive Transport requires no extra energy by the cell because molecules move from high concentration (squished together) to low concentration (spread out) areas down the concentration gradient.
Active Transport requires extra energy (ATP) to be spent to bring materials into the cell or expel materials out of the cell moving from low concentration to high concentration against the concentration gradient.

6. Examples of Transport Passive Transport Diffusion Osmosis
Facilitated Diffusion
Active Transport
Molecular Pumps
Exocytosis
Endocytosis

7. Words to Know Solute – what gets dissolved (Ex. Lemonade powder)
Solvent – does the dissolving (Ex. Water)
Solution – uniform mixture of two or more substances (Ex. Lemonade)
Concentration – amount of solute dissolved in solvent
Symbol for abbreviation = [ ]

8. Passive Transport: Diffusion
The spreading out of molecules across a membrane until they are equally concentrated on both sides of the membrane.
Molecules move down a concentration gradient, from high [ ] to an area of low [ ]
Ex. Oxygen and Carbon Dioxide
Over time…

10. Passive Transport: Facilitated Diffusion
A transport protein acts as a protein channel to help (facilitate) the diffusion of molecules that normally couldn‘t pass through the cell membrane
Molecules move down a concentration gradient, from high [ ] to an area of low [ ]
Ex. Glucose/sugar, sodium/salt
Over time…

11. Passive Transport: Osmosis
The diffusion of water across the cell membrane
Water molecules move down a concentration gradient, from high [ ] to an area of low [ ]

12. Passive Transport: Osmosis
Hypertonic solutions: water concentration is below what is found in a cell’s cytoplasm.
Water will tend to move out of the cell, down its concentration gradient  Cell shrinks
Hypotonic solutions: water concentration is above what is found in a cell’s cytoplasm.
Water will tend to move into a cell, down its concentration gradient  Cell swells
Isotonic solutions: identical water concentrations to what is found in a cell’s cytoplasm  Cell stays the same

13. Passive Transport: Osmosis
Hypertonic
Hypotonic
Isotonic
H2O
H2O
H2O
H2O
H2O
H2O
Cell stays the same
Cell shrivels
Cell swells

15. Active Transport
Remember – not all substances can move so freely into a cell.
Some molecules have to be pushed “uphill,” against a concentration gradient.
This means substances are moving from an area of low [ ] to an area of high [ ]
Other substances are too big to move through a protein channel, and have to be enveloped by the cell or excreted by the cell.
This is accomplished by either endocytosis or exocytosis.

16. Active Transport: Molecular Pumps
When a cell uses energy to pump molecules across the membrane through a protein channel.
This allows a cell to concentrate key molecules within the cell, or remove waste quickly from the cell.
Ex. Calcium (Ca2+), potassium (K+), chlorine (Cl-) and sodium (Na+) = ions (charged particles)
ENERGY
Over time…

18. Active Transport: Endocytosis
A cell uses energy to import large amounts of materials INTO the cell using a vesicle
Ex. White blood cells engulf bacteria to fight infection

19. Active Transport: Exocytosis
A cell uses energy to export large amounts of materials OUT OF the cell using a vesicle
Ex. Nerve cells release neurotransmitters to pass signals to the brain

20. Practice Time! Type of Transport Passive/Active
Ex. of what is being moved
How it helps maintain homeostasis
Facilitated Diffusion
Regulates blood sugar
Active
Neurotransmitters
Endocytosis
Captures bacteria
Passive
Controls blood pressure by regulating blood volume
O2 and CO2
K+, Na+, Ca2+, Cl-
Muscle contractions and nerve signal conduction
Have students fill this chart in (the best that they can) and go over.