1. The cell membrane and cell wall
The Cell Boundaries
The cell membrane and cell wall

2. The borders
The most important parts of a cell are its borders, which separate the cell from its surroundings.
All cells are surrounded by a thin flexible barrier known as ____________

3. The Cell Membrane

4. What type of cell would have these?
The borders
--- Some cells produce a strong supporting layer around the membrane known as the cell wall.
What type of cell would have these?

5. Plant Cells

6. The cell membrane regulates what enters and leaves the cell
--- Cell membranes are made of a double layer sheet called a lipid bilayer.

7. REMEMBER!!!! What is a lipid?
Lipids
REMEMBER!!!! What is a lipid?

8. Definition of a Lipid
A lipid is a type of organic compound found in all living things. Lipids are not soluble in water and are made of carbon and hydrogen atoms.

9. Lipid Bilayer
The lipid bilayer gives the cell membrane a flexible structure that forms a strong barrier between the cell and its surroundings

12. Proteins
Most cell membranes contain protein , which are embedded in the lipid bilayer.
---- Some of the proteins form channels and pumps that help to move material across the cell membrane.

13. Important
**** One of the most important functions of the cell membrane is to regulate the movement of dissolved molecules to the liquid side on the other side.

14. Transport Across Membranes
What is Diffusion, Osmosis, Facillated diffusion and Active Transport

15. Cellular Transport
Cellular transport is the process of molecules or material moving in and out of the cell
There are two types of transport within the cell.
Passive Transport
Active Transport

16. Passive Transport
Passive transport is the movement of molecules in or out of the cell without the use of energy
Can only occur if the molecules moving in and out of the cell are:
Small
Uncharged (meaning they contain NO + or – which are ions)
Move from an area of high concentration to an area of low concentration
There are three types of passive transport: diffusion, osmosis, and facilitated diffusion

17. Diffusion
Movement of particles from an area of higher concentration to an area of lower concentration until an equilibrium is established
doesn’t require energy

18. Note:
In the cell membrane if a substance has an unequal concentration on either side the particles will move to the area of low concentration until an equilibrium is established

19. Here is example

20. Osmosis
Diffusion of water across a selectively permeable membrane (some substances can pass through and some can’t)

21. Watch the Example

22. Osmotic pressure
For an organism to survive it must have a way balance the intake and loss of water.
Pressure produced by osmosis can sometimes be fatal to plant and animal cells
Keep in mind water follows the solute

23. Before we begin.
What do the prefixes mean:
a. iso
b. hyper
c. hypo

24. Hypertonic Solution solution has a higher solute concentration outside the cell; too much outside of the cell
In plant cells,
- cell will become plasmolyzed (shrink)
In animal cells,
- cell will lyse (shrink)

25. Hypotonic Solution lower solute concentration outside of the cell than inside
In animal cells
- cell will become
swollen and burst
In plant cells,
- cell will become turgid (very firm, swollen and hard)
- this is normal for plant cells

26. Isotonic Solution there is the same solute concentration inside and outside of the cell
In animal cells
- the cell will be
normal
In plant cell
- will be flaccid (limp)
**green parts of the plant droop and are unable to hold their leaves towards the sun**

27. Let’s watch another example

28. Facilitated Diffusion
Movement of specific molecules across cell membranes through protein channels.
These specific molecules bind to a protein and are channeled from the outside of the cell to the inside
Is fast and specific
Will still only occur if concentration is higher on one side of the membrane than the other.

29. Molecular Transport
Small molecules and ions are carried across membranes as in facilitated diffusion, but require energy because they are going against the concentration gradient
These proteins behave as pumps that require energy to move molecules and ions sometime against the concentration gradient of diffusion.

30. Active Transport
The passing of molecules across a membrane against the concentration gradient
Requires energy
Small molecules are transported by pumps (molecular transport)
Larger molecules are transported by endocytosis and exocytosis.

31. Endocytosis
Process of taking material into the cell by means of forming a vesicle or pockets of the cell membrane
This takes material into the cell and it forms a vacuole in the cell
Large molecules of food and whole cells can be taken this way

32. Two Types of Endocytosis
Phagocytosis
Means “cell eating”
An extension of cytoplasm surrounds a particle and package it into a food vacuole
requires an enormous amount of energy
Pinocytosis
Means” cell drinking”
Tiny pockets form along the cell membrane fill with liquid and form vacuoles with in the cell
Requires enormous amounts of energy

33. Exocytosis The process where cells release large amount of materials
Vacuole surrounding material fuses with the cell membrane, forcing the contents out of the cell
Also requires energy

34. Cell Wall
Cell walls are not found in animal.
--- They are located outside the cell membrane.
---- They are porous, which allow water, oxygen, carbon dioxide and other substances to pass through.

35. Cell Wall
Plant cell walls are made mostly of cellulose , a tough carbohydrate fiber.

36. Solutions
The cytoplasm of a cell contains a solution of many different substances in water.

37. Solution What is a solution?
A solution is a mixture of two or more substances in which the molecules of the substance are evenly distributed

38. So let’s wrap it all up
First video

39. Compare an contrast diffusion and osmosis.
Give me and example of what happens to a cell if an isotonic, hypotonic, or hypertonic solution is present?
What is facillated diffusion?
Explain active transport
What happens during molecular transport
Describe endocytosis
Contrast phagocytosis and exocytosis?
What happens during exocytosis?