1. Chapter 3 Cell Processes

2. Ch. 3-2 Moving Cellular Materials

3. Structure of the Cell Membrane
The Plasma Membrane
9/18/2018
Structure of the Cell Membrane
G. Podgorski, Biol. 1010

4. The Plasma Membrane
Cell Membrane
9/18/2018
The cell membrane is made of 2 layers of phospholipids called the lipid bilayer.
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5. Close that window!!!
There are many reasons we open and shut the windows in our house.
Do you want to let all of the bugs and leaves in?
A window screen provides the protection to keep unwanted things outside, but it also allows some things to pass into and out of the room like air, unpleasant odors, or smoke.
How does the cell membrane carry out similar functions to that of a window screen?

6. The cell membrane
A cell membrane, like a screen, will let some things through more easily than others.
Ex: Air gets through a screen, but insects are kept out.
A cell’s membrane is “selectively permeable”. In other words it allows some things to enter or leave the cell while keeping other things outside or inside of the cell.

7. The Plasma Membrane
9/18/2018
Solubility
Materials that are soluble in lipids can pass through the cell membrane easily.
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8. What determines how particles move in and out of the cell?
Which way particles move depends on the
a) size of the molecule or particle,
B) the path taken through the membrane,
c) whether or not energy is used.

9. Semipermeable Membrane
The Plasma Membrane
Semipermeable Membrane
9/18/2018
Small molecules move through easily.
e.g. O2, CO2, H2O (oxygen, carbon dioxide, water)
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10. Semipermeable Membrane
The Plasma Membrane
Semipermeable Membrane
9/18/2018
Molecules larger than water, (such as proteins), do not move through the membrane on their own.
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11. Types of Transport Across Cell Membranes
The Plasma Membrane
9/18/2018
Types of Transport Across Cell Membranes
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12. Moving things “without energy”
The movement of substances through the cell membrane “without using energy” is called passive transport.
The cell membrane can move things into and out of the cell without using energy either by:
Simple diffusion
Osmosis
Facilitated diffusion

13. Diffusion Simple Diffusion Doesn’t require energy
The Plasma Membrane
9/18/2018
Diffusion
Simple Diffusion
Doesn’t require energy
Moves from high to low concentration
Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out.
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14. Simple Diffusion In other words
The Plasma Membrane
9/18/2018
Simple Diffusion
In other words
Molecules move from crowded to less crowded areas of concentration.
This can occur in solids, liquids, and gases.
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15. Diffusion “in action”…..
You might smell perfume when you sit near or walk past someone wearing it. This is because the perfume molecules are randomly moving throughout the air .
The molecules are going from an area that is crowded (such as inside the bottle) to a less crowded area (such as the air itself).
There’s more space for the molecules to spread out and move in the air.
Diffusion stops once there is an equal number of molecules in both areas.
The molecules are in equilibrium.

16. The Plasma Membrane
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DIFFUSION
Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY
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17. Diffusion of Liquids The Plasma Membrane 9/18/2018
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18. Diffusion through a Membrane
The Plasma Membrane
9/18/2018
Diffusion through a Membrane
Cell membrane
Solute moves DOWN concentration gradient (HIGH to LOW)
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19. Let’s Take a Look!
Animation of How Diffusion Works

20. Diffusion across a membrane
The Plasma Membrane
9/18/2018
Osmosis
Diffusion across a membrane
Diffusion of “water” across a membrane
Moves from HIGH water potential (low solute) to LOW water potential (high solute)
Concentration = the amount of a substance in a given volume.
semi-permeable membrane
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21. Diffusion of H2O Across A Membrane
The Plasma Membrane
9/18/2018
Diffusion of H2O Across A Membrane
High H2O potential Low solute concentration
Low H2O potential High solute concentration
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22. Click on Picture for Animation

23. Practice: Sample 1 CELL 10% NaCl 90% H2O 20% NaCl 80% H2O
The Plasma Membrane
9/18/2018
Practice: Sample 1
10% NaCl 90% H2O
ENVIRONMENT
CELL
20% NaCl
80% H2O
What is the direction of water movement?
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24. Practice: sample 2 CELL 15% NaCl 85% H2O 5% NaCl 95% H2O
The Plasma Membrane
9/18/2018
Practice: sample 2
15% NaCl 85% H2O
ENVIRONMENT
CELL
5% NaCl
95% H2O
What is the direction of water movement?
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25. Practice 3…. CELL What is the direction of water movement?
The Plasma Membrane
9/18/2018
Practice 3….
10% NaCl 90% H2O
ENVIRONMENT
CELL
NO NET MOVEMENT
10% NaCl
90% H2O
What is the direction of water movement?
The cell is at _______________.
equilibrium
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26. Practice 4 CELL What is the direction of salt (NaCl) movement?
40% NaCl 60% H2O
ENVIRONMENT
CELL
20% NaCl
80% H2O
What is the direction of salt (NaCl) movement?

27. Practice 5 CELL What is the direction of salt (NaCl) movement?
20% NaCl 80% H2O
ENVIRONMENT
CELL
90% NaCl
10% H2O
What is the direction of salt (NaCl) movement?

28. Wrapping it up... 1. What is the “fuel” for all cells? ________
2. Diffusion is the movement of particles from
________ areas of concentration to areas
of __________ concentration.
3. Osmosis is a specialized type of diffusion
that involves the movement of ___________.

29. Bellwork questions…..

30. A simple rule to remember is: salt sucks
Salt is a solute. When it is concentrated inside or outside the cell, it will draw the water in its direction.
This is also why you get thirsty after eating something salty!
30% salt
70% water
The addition of salt in the container lowers the concentration of water.
The water concentration is higher in the cells of the flower.
“container”
100% water
0% salt
“Flower”

31. What happens when you put salt on a snail?
They will shrivel up!!!
Why?
The bodies of snails and slugs contain much water in them.  Due to the process of osmosis, in the scenario of salt and snails, the snails act as the area with high water concentration. On the other hand, the salt that you add to the snails has a low water concentration.
The snails really do not melt when we add salt.  They dry up because too much water in their bodies is sucked out of them and into the salt.  The poor snails shrivel up and die as a result.

32. Bellwork Draw the illustration…
The Plasma Membrane
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Bellwork Draw the illustration…
25% NaCl 65% H2O
ENVIRONMENT
CELL
35% NaCl
35% H2O
What is the direction of water movement?
What is the direction of the salt (NaCl)?
Explain your answer.
Into the cell
Out of the cell
Molecules move from areas of high concentration to lower concentration
G. Podgorski, Biol. 1010

33. What do you think?
A fish that is accustomed to living in salt water is placed in fresh water. What do you predict might happen to the cells of the fish?
A. They might shrink up and cause the fish to die.
B. They would become healthier because the water is so fresh.
C. They might burst and cause the fish to die.

34. What do you think? C. They might burst and cause the fish to die.
A fish that is accustomed to living in salt water is placed in fresh water. What do you predict might happen to the cells of the fish?
A. They might shrink up and cause the fish to die.
B. They would become healthier because the water is so fresh.
C. They might burst and cause the fish to die.

35. The process of osmosis would explain the net movement of water into a cell if the percentage of
water was 90% inside the cell and 95% outside the cell
water was 95% inside the cell and 90% outside the cell
protein was 30% inside the cell and 35% outside the cell
water and protein was equal inside and outside the cell

36. water was 90% inside the cell and 95% outside the cell
The process of osmosis would explain the net movement of water into a cell if the percentage of
water was 90% inside the cell and 95% outside the cell
water was 95% inside the cell and 90% outside the cell
protein was 30% inside the cell and 35% outside the cell
water and protein was equal inside and outside the cell

37. Facilitated diffusion (passive transport)
The Plasma Membrane
9/18/2018
Facilitated diffusion (passive transport)
Doesn’t require energy
Uses transport proteins to move material from high to low concentration
Examples: Glucose or amino acids (chain of proteins) moving from blood into a cell.
G. Podgorski, Biol. 1010

38. Facilitated Diffusion
The Plasma Membrane
9/18/2018
Facilitated Diffusion
Molecules will randomly move through the pores of the cell membrane in protein channels.
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39. Facilitated Diffusion
The Plasma Membrane
9/18/2018
Facilitated Diffusion
Some carrier proteins do not extend through the membrane.
They bond and drag molecules through the lipid bilayer and release them on the opposite side.
G. Podgorski, Biol. 1010

40. Brainpop on “passive transport”
The Plasma Membrane
9/18/2018
Brainpop on “passive transport”
passive transport
Brainpop titled “passive transport”
G. Podgorski, Biol. 1010

41. BellFUN Finish your diffusion practice sheet so we can go over it.
**Fred pours the salty water from his ice cream maker on the grass in his yard.
What will happen to the grass and why?
Finish your diffusion practice sheet so we can go over it.

42. Active Transport Requires energy (or ATP)
The Plasma Membrane
9/18/2018
Active Transport
Requires energy (or ATP)
Moves materials from LOW to HIGH concentration. It goes
AGAINST the concentration gradient
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43. Large molecules move materials into the cell by endocytosis.
The Plasma Membrane
Moving the “Big Stuff”
9/18/2018
Large molecules move materials into the cell by endocytosis.
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44. Endocytosis It takes in dissolved molecules as a vesicle. .
The Plasma Membrane
Endocytosis
9/18/2018
It takes in dissolved molecules as a vesicle.
This is sometimes called “Cell drinking”. .
G. Podgorski, Biol. 1010

45. Exocytosis- moving large things out.
The Plasma Membrane
Moving the “Big Stuff”
9/18/2018
Exocytosis- moving large things out.
Large molecules are moved out of the cell by vesicles that fuse with the cell membrane through exocytosis.
This is how many hormones are secreted and how nerve cells communicate with one another.
G. Podgorski, Biol. 1010

46. Brainpop on active transport
The Plasma Membrane
9/18/2018
Brainpop on active transport
active transport
Assignment:
Create your own illustrations of passive transport, active transport, endocytosis, and exocytosis. Color and label. Yes, you may use the book as a guide.
Brainpop titled “active transport” /worksheet p. 28 in teacher resource book
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47. Bellwork
1. The arrows in the diagram represent the direction of movement of a certain type of molecule through the cell membrane of two different cells. The dots represent the relative concentrations of this molecule. Which processes are illustrated in the diagram?

48. Review
Happy Science Day! Examine how the particles in each example are moving and tell if the process is osmosis, equilibrium, simple diffusion, facilitated diffusion, or active transport.

49. Examine how the particles in each example are moving and tell if the process is osmosis, equilibrium, simple diffusion, facilitated diffusion, or active transport.

50. Examine how the particles in each example are moving and tell if the process is osmosis, equilibrium, simple diffusion, facilitated diffusion, or active transport. 5.