1. Cell Boundaries

2. Regulating Cell Environment
The cell has to be able to regulate its internal environment.
Its internal environment is very different than the external environments that it is bathed in.
Cells use cell walls and cell membrane to control its environment.
Most cells except for animal cells have cell walls.
They are composed of carbohydrates depending on the kingdom.
Cell walls are dead and are used to prevent the cells from bursting and give them structures.

3. Some Cell Wall Carbohydrates
Bacteria-Muramic acid (modified sugars held with peptide cross linkages)
Plants-Cellulose
Fungi-Chitin

4. Cell walls are porous and allow most anything to cross-the cell membrane is a barrier that regulates what gets “into or out of” the cell.
In plant cells, the first cell wall that is laid down is the primary cell wall and is elastic. The middle lamella is the layer holding adjacent cells together.

5. Plant cells with soft tissue have only one cell wall
Plant cells with soft tissue have only one cell wall. Harder cells lay down a secondary cell wall.
This is laid inside the primary cell wall and is thicker.

6. Summary
Cell walls- found in all cells except animal cells. Gives cell shapes and prevents it from bursting. Porous most everything crosses wall.
Plants made of cellulose
Prokaryotes made of maramic acid
Fungi made of chitin
Plants may have 2 cell walls- primary wall elastic. Secondary cell wall hardened with lignin. Middle lamella hold cells together.

7. All cells have cell membranes
All cells have cell membranes. The basic structure is a bilayer of phospholipids with proteins and cholesterol inserted in the layer.
This model is the fluid mosaic layer of cell membranes.

8. Phospholipids are modified triglycerides
Phospholipid with atoms illustrated:
Phospholipids usually illustrated such as:

9. Summary: All cells have cell membranes
And it regulates what gets into and out of the cell.
Structure is a bilayer of phospholipids with proteins and cholesterol in the layer.
Called fluid mosaic model

10. Basic Cell membrane Has two layers of phospholipids as seen below
The phosphate heads are facing water-inside and outside the cell, keeping the hydrocarbons away from it

11. Summary: Cell membrane
Phosphate heads face the water-inside and outside, the hydrocarbon tails face one another
Proteins are “stuck” in the membrane like a mosaic (intrinsic) or can be on the surface (extrinsic)
Functions of membrane proteins
1.Used as transport
2.Used as receptors or as enzymes
3.Used as attachment for cytoskeleton

12. Glycolipid

13. Summary: Cell membranes
Cell membranes are semi permeable or (selectively permeable) because some molecules can pass the membrane and others can not
Permeable are molecules that can pass the membrane usually small molecules (O2 and CO2) and lipids like steroids
Impermeable are molecules that can not cross the membrane usually large molecules, polar molecules and ions

14. Passive Diffusion
The molecules (CO2, O2, etc) involved are permeable to the membrane.
Predicting the net movement as if there was no membrane at all. The molecules move from high to low concentration.
In the first system, A is more concentrated on side than side 1.
A is permeable
Net movement Side 2 to 1
Equilibrium is reached
Equal movement on both sides

15. Summary:
Passive diffusion- is the movement of permeable material across the membrane.
The net movement of material is from high concentration to low concentration until equilibrium is reached. Then the movement of material across the membrane will be equal in both directions

17. Summary: Facilitated Diffusion
Smaller, charged or polar molecules (glucose, amino acids, etc.) are impermeable to the membrane.
A transport protein is needed.
The net movement is like passive diffusion moving from high to low concentration.

20. Active Transport
Active transport-molecules are impermeable to the membrane
The molecules are moving against the concentration gradient (from low to high).
A transport protein and ATP are needed.

21. Osmosis Is a special case of movement of water.
When things are impermeable to the membrane, and not in equilibrium, water will move across the membrane to help reach equilibrium.
“Water likes to dilute”

22. Terms
Hypertonic-higher concentration of solutes. Lower concentration of water
Hypotonic-lower concentration of solutes. Higher concentration of water
Isotonic-Two solutions that have equal solutes on both sides of the membrane

23. What is happening and Why?

24. Think pair share! What is happening? Why ? Animal cell? Plant cell?
Name the process
Net movement

26. Movement of Molecules Using the Cell Membrane
Endocytosis- is movement of larger particles into the cell by use of membrane vesicles.
Two Types:
Phagocytosis-cell eating
Pinocytosis-cell drinking
Exocytosis-is the movement of larger particles out of the cell by use of membrane vesicles.

29. http://highered. mcgraw-hill. com/olcweb/cgi/pluginpop. cgi