1. The Membrane
Plasma membranes are amphiphilic which means they have hydrophilic and hydrophobic regions.
Hydrophilic – attracted to water
Hydrophobic – “scared” of water
Cell membranes are selectively or semi permeable which means that some materials move through the membrane and hinders the movement of others.
The cell membrane is primarily composed of a mix of proteins & lipids
Lipids help to give membranes their flexibility, proteins monitor and maintain the cell's chemical climate and assist in the transfer of molecules across the membrane.

3. The Membrane Lipids
Phospholipids: form a lipid bilayer in which their hydrophilic head areas arrange to face the cytosol and the extracellular fluid, while their hydrophobic tail areas face away from the cytosol and extracellular fluid.

4. The Membrane Lipids
Cholesterol molecules are selectively dispersed between membrane phospholipids. This keeps the cell membranes from becoming stiff by preventing phospholipids from being too closely packed together. Glycolipids are located on cell membrane surfaces and have a carbohydrate sugar chain attached to them. They help the cell to recognize other cells of the body.

5. The Membrane Proteins
Peripheral Proteins help cells communicate with their external environment
Channel or Transport proteins transport molecules across cell membranes through facilitated diffusion
Integral Proteins are embedded in the cell membrane and help in cell to cell communications and molecule transport across the membrane.

6. What will move?
Fat-soluble material with a low molecular weight can easily slip through the hydrophobic lipid core of the membrane.
Fat soluble vitamins readily pass through the plasma membranes in the digestive tract and other tissues.
Fat-soluble drugs and hormones also gain easy entry into cells and are readily transported into the body's tissues and organs.
Molecules of oxygen and carbon dioxide have no charge and so pass through membranes by simple diffusion.

7. What will move?
Small ions could easily slip through the spaces in the membrane BUT their charge prevents them from doing so.
Ions such as sodium, potassium, calcium, and chloride are PUMPED against the concentration gradient into a cell by active transport
Simple sugars (glucose) and amino acids also need help with transport across plasma membranes, achieved by various membrane proteins (channels).

8. Transportation Mechanisms

9. What are the jobs cells need to do?
Get food
Convert energy
Remove wastes
Reproduce
Grow and repair
Transport substances

10. How does a cell do its jobs?
The Cell membrane has two main functions:
1) Forms a boundary between the cell’s internal and external environment (like your skin)
2) Controls the movement of substances into and out of the cell.
**It is Selectively Permeable (it only lets some things through)

11. How Cells Move Molecules
1) Passive Transport
a) Diffusion: small molecules like water, oxygen, and carbon dioxide pass through the cell membrane easily
The membrane is permeable (are allowed through) to these molecules
Molecules move down concentration gradient
Can be called SIMPLE DIFFUSION in which molecules move down the [ ] gradient Or FACILITATED DIFFUSION, which use a channel or transport protein to move molecules
****All types of Diffusion: Does not require energy*****

12. How Cells Move Molecules
Concentration Gradient: Molecules will move from areas of high concentration to low concentration
Example:
People at party will try to move out of the crowded room at a party because it's more comfortable. Molecules do the same thing.

13. How Cells Move Molecules
Osmosis is the diffusion of Water
Movement of water is from an area of high water concentration to an area of low water concentration

14. How Cells Move Molecules
Solute: particles which are dissolved in water
Ex: Salt or sugar
Solvent: the liquid that the particles are dissolved in

15. TYPES OF SOLUTIONS
Hypertonic - Higher solute concentration outside of the cell than inside the cell
More water inside than out initially
Water diffuses out by osmosis

16. TYPES OF SOLUTIONS
Hypotonic - Higher solute concentration inside the cell than outside the cell
 Less water inside than out initially
 Water diffuses in by osmosis

17. TYPES OF SOLUTIONS
Isotonic - Equal solute concentrations inside and out
water doesn't move

18. TYPES OF SOLUTIONS
Human cells are very sensitive to changes in concentration of the blood

19. How Cells Move Molecules
2) Active Transport: Moves materials across the cell membrane against a concentration gradient (low to high conc.)
Requires the use of energy
Allows cells to collect certain substances in concentrations hundreds of times higher than those outside the cell

20. How Cells Move Molecules
3) Endocytosis & Exocytosis:
 Cells use a process of taking materials into cell (endocytosis) & removing materials from cell (exocytosis)

21. Phagocytosis aka. “Cell Eating” The movement of solid particles through the cell membrane as it pinches off to form a Transport vessicle.

22. Pinocytosis aka. “Cell Drinking” The movement of dissolved particles through the cell membrane as it pinches off to form a Transport Vessicle.

23. Receptor Mediated Endocytosis The movement of dissolved particles through the cell membrane ONLY if they find a corresponding Receptor.

24. Energy & The Cell

25. Cells and Energy
We’ve learned in previous lessons that cells use energy- active transport and endocytosis and exocytosis.
Where does the energy come from?

26. Chemical Energy and ATP
Energy comes in many forms, including light, heat, and electricity. Energy can be stored in chemical compounds, too.
For example:
when a candle burns, carbon and hydrogen in the wax combine with oxygen from the air to produce water and carbon dioxide.
This process releases energy in the form of light and heat.

27. Where does energy for a cell come from?
Cellular Respiration!
This process where glucose molecules are oxidized. During this process energy that was stored in the glucose bonds are released.
Glucose + Oxygen  Carbon dioxide + water + energy

28. Energy
Living things store energy mainly in the form of chemical bonds. Within your cells, energy is constantly moved around from one large molecule to another.
How does the energy get converted from a food molecule to a muscle molecule?
The answer is adenosine triphosphate (ATP)

29. In the mitochondria…
The energy molecule cells use is called adenosine triphosphate (ATP)
-The phosphate groups are all negatively charged (repel each other)
It takes a LOT of energy to force the phosphate groups together
Bonds are similar to springs- they store energy.
When spring is released, energy is released.
When the bonds are broken, energy is released.

30. ATP
-The energy of ATP can be used in a cell when the phosphate groups are broken off
-When one phosphate molecule breaks off, ADP is formed and energy is released
 -another phosphate can be bonded on to remake ATP once again (Renewable energy)

31. ATP
Being able to form and breakdown ATP helps the cell to store store ALL the ATP (energy) it needs
it makes the energy as it needs it
ATP is a small molecule that can attach to a cell while the energy is needed
when the phosphate group has been broken off, the ADP molecule is released and a new phosphate can attach.

32. ATP vs ADP

33. Animation or video
(until 4:10)