1. Copy into journal -Vocab Word list
Diffusion
Osmosis
Selectively permeable
Equilibrium
Solution
Facilitated Diffusion
Hypertonic
Hypotonic
Isotonic
Contractile Vacuole
11. Passive Transport
12. Active Transport
13. Endocytosis
14. Phagocytosis
15. Pinocytosis
16. Exocytosis
17. Protein Pump
Know all of these words for the test

2. Transport Across the Cell Membrane
Fluid Mosaic Model Video clip
Silent video- cell membrane and how it works

3. I. Structure of the Cell Membrane
2 layers (bilayer) of phospholipids with proteins imbedded
known as the FLUID MOSAIC MODEL (molecules are in motion)
Philic heads = water loving
Phobic tails= water fearing
This helps the cell interact in its aqueous environment.

4. II. The FUNCTIONS of the Cell Membrane
Cell membranes help organisms maintain homeostasis by controlling what substances may enter or leave cells
Boundary between the cell’s external and internal environment (like a Gatekeeper)

5. 3. Selectively permeable – some molecules can cross it; others cannot – often based on size
small molecules (H2O, CO2, O2) cross
large molecules (starch, protein) cannot
small molecule
(water, carbon dioxide, oxygen)
large molecule
(starch, protein)
cell membrane

6. To stay alive, a cell must exchange materials such as food, water, & wastes with its environment
Molecules they want to let in:
Molecules they want to let out:
Molecules they DO NOT want to let in:
Some substances can cross the cell membrane without any input of energy by the cell……often based on size
The movement of such substances across the membrane is known as passive transport – without the use of energy
sugar, oxygen, water
carbon dioxide, waste
viruses, bacteria

7. Receives, recognizes & responds to signals from other cells
4. Cell-to-cell communication
Receives, recognizes & responds to signals from other cells
The proteins attached to the surface of the cell membrane act as receptors for molecules like hormones or neurotransmitters (chemical produced by nerve cells).
Cell
Membrane
Advanced video Click on image

8. Functions of the Cell Membrane
The SHAPE of the
cell receptor matches
the SHAPE of the
chemical signal, like a
lock and key or puzzle
pieces.

9. Example of a Cell Receptor: Hormone
Signal
(ex. hormone)
Has receptors that match the hormone
The binding of the hormone or neurotransmitter to the receptor results in a change in the cell’s metabolism.

10. Example of a Cell Receptor: neurotransmitter
(signal)

11. Molecules that stop the signal from binding to the receptors prevent the cell from responding to the signal.
These molecules are called inhibitors.
(signal)

12. Specificity
In biology, specificity refers to molecules that have a particular affinity for, or attachment to, each other
In other words, they must fit together in order to function

13. YOUR TURN: Match the hormone to its target cell
Cell A Cell B Cell C
Hormone # 1 Hormone # Hormone # 3
What is the target cell for hormone #1?
What is the target cell for hormone #2?
What is the target cell for hormone #3
Cell B
Cell C
Cell A

14. Question 1.
Which statement regarding the functioning of the cell membrane of all organisms is not correct?
The cell membrane forms a boundary that separates the cellular contents from the outside environment.
The cell membrane forms a barrier that keeps all substances that might harm the cell from entering the cell.
The cell membrane controls the movement of molecules into and out of the cell.
The cell membrane is capable of receiving and recognizing chemical signals.

15. Question 2.
In the given diagram of a single-celled organism, that arrows indicate various activities taking place.
Which systems perform these same activities in humans?
Respiratory, nervous and endocrine
Excretory, respiratory, and reproductive
Digestive, circulatory, and immune
Respiratory, excretory, and digestive

16. Question 3. Cellular communication is illustrated in the diagram below
Information can be sent from
Cell A to Cell B because cell B is able to recognize signal 1
Cell B to Cell A because cell B is able to recognize signal 2
Cell B to Cell A because cell A is able to recognize signal 1
Cell A to Cell B because cell A is able to recognize signal 2

17. Question 4.
Which substance are found on cell surfaces and respond to nerve and hormone signals?
Vitamins and minerals
Subunits of DNA
Receptor molecules
Starches and simple sugars

18. Question 5.
Hormones and secretions of the nervous system are chemical messengers that
Store genetic information
Extract energy from nutrients
Coordinate system interactions
Carry out the circulation of materials

19. Question 6.
In multi-celluar organisms, cells must be able to communicate with each other. Structures that enable most cells to communicate with each other are known as
Chloroplasts
Pathogenic agents
Receptor molecules
Antibiotics

20. TYPES OF TRANSPORT Across the Membrane Active & passive transport -
No energy required
Energy required

21. 1. Passive Transport A. Diffusion Requires NO energy
Requires NO energy
A. Diffusion
molecules move from an area of high concentration to an area of low concentration
Molecules move down the concentration gradient - like going down a slide.
Click on image to see
How Diffusion works

22. Dynamic EquilibriuM
when molecules “spread out” evenly throughout a space and stay in motion.

23. The rate of diffusion depends on temperature, size/surface area of the molecules, & type of molecules diffusing
Substances that may diffuse:
O2, CO2, glucose, amino acids, H2O

24. B. Osmosis Diffusion of water molecules. Watch How osmosis works:

25. Diffusion Demo – copy into Journal
Indicator- substance that changes color in the presence of the substance it tests for
Iodine (reddish -brown color) tests for starch.
A positive test would change the color to a blue-black
BEFORE AFTER
Color of bag (cell): _______ Color of bag (cell): _______
Contents of bag: ________ Contents of bag: ________
Time lapse
Semi- permeable membrane of cell
starch
iodine
Cloudy white
starch

26. Cells in different osmotic solutions (tonicity)
Cells behave differently when placed in different solutions!
This is due to OSMOSIS! Most cells are ~ 98% water!
Three types of osmotic pressure:
Isotonic
Hypotonic
Hypertonic
Basic Rule for Determining types of Osmotic conditions….
Salt “SUCKS” – IT ACTUALLY ATTRACTS THE WATER
If the area outside the cell has more salt – then water will be “pulled” out of the cell

27. Isotonic - "ISO" means the same
90% water
90% water

28. Let’s see….Isotonic Condition
Cell is placed in 98% water
Solution outside of cell has SAME water, same amount of other materials (i.e., salt)
Therefore, solution is equal strength (iso)
Water moves equally;
Equilibrium exists
98%
CELL
STAYS
THE SAME!
98%

29. Hypotonic (Hypo = less)
Water moves in the cell
Cell may burst, or organelles called “contractile vacuoles” remove excess water
90% water
80% water

30. Example of Osmosis Condition #1: More Water outside of cell
Inside cell = 98% Water, 2% salt
Outside cell = 100% Water, 0% salt
98% L
Water moves into cell
CELL SWELLS or
BURSTS!
100% H
CLICK HERE FOR DEMO!

31. HYPERTONIC – “Hyper = above”
Water moves out of cell
Cell will shrink (Plasmolysis) or die, plants wilt
80% water
Why is it dangerous to drink sea water?
Why does pouring salt on a slug kill it?
90% water

32. Example of Osmosis Condition #2: More water inside of cell
Inside cell: 98% Water, 2% Salt
Outside cell: 95% Water, 5% Salt
98% H
Water moves out of cell
95% L
CELL SHRIVELS!

33. Water relations and Cell shape in cells
Animal cell: RBC
Plant Cell
HYPERTONIC
HYPOTONIC
HYPERTONIC
HYPOTONIC

34. C. Facilitated Diffusion
form of passive transport
Facilitate- to guide or help.
Protein channels help guide some molecules through the cell membrane.

35. Diffusion Demo – Journal entry
Indicator- substance that changes color in the presence of the substance it tests for
Iodine (reddish -brown color) tests for starch.
A positive test would change the color to a blue-black
BEFORE AFTER
Color of bag (cell): _______ Color of bag (cell): _______
Contents of bag: ________ Contents of bag: ________
Time lapse
Semi- permeable membrane of cell
starch
Starch & iodine
iodine
Blue-black
cloudy white
starch
Starch & iodine

36. 2. Active Transport
Movement of molecules from areas of low concentration to areas of high concentration.
Requires ATP (energy).
The molecules move against/up the concentration gradient – like climbing a mountain.
Teacher’s Pet video:

37. Comparing Types of Transport
video:

38. Examples of Active Transport :
Endocytosis- bring into the cell.
Phagocytosis = Cytoplasm extends out and
engulfs material to be brought into the cell.
Ex. White blood cells and amoeba.
2. Exocytosis- move out of the cell.
Watch phagocytosis animation:

39. Endocytosis and Exocytosis

40. Watch Summary video
mfu
Active & passive transport -

41. “Everyday” Examples of Diffusion in the Human Body
1) absorption of nutrients
What : nutrients (glucose, amino acids)
From : small intestine
To : blood
Where : villi

42. What : oxygen carbon dioxide From : lungs blood To : blood lungs
2) gas exchange
What : oxygen carbon dioxide
From : lungs blood
To : blood lungs
Where : alveoli
3) in the placenta
What : oxygen, carbon dioxide,
nutrients wastes
From : mom baby
To : baby mom
Where : uterus