1. Cell Boundaries

2. Macromolecules in cells!
All the cell parts are made up of these macromolecules 
We will start with just looking at cell boundaries

3. KEY CONCEPT The cell membrane is a barrier that separates a cell from the external environment.

4. Cell membranes are composed of two phospholipid layers.
The cell membrane has two major functions.
cell membrane

5. Cell membranes are composed of two phospholipid layers.
The cell membrane has two major functions.
forms a boundary between inside and outside of the cell
cell membrane
outside cell
inside cell

6. Cell membranes are composed of two phospholipid layers.
The cell membrane has two major functions.
forms a boundary between inside and outside of the cell
controls passage of materials
cell membrane
outside cell
inside cell

7. Cell membranes are composed of two phospholipid layers.
The cell membrane is made of a phospholipid bilayer.
cell membrane

8. Cell membranes are composed of two phospholipid layers.
The cell membrane is made of a phospholipid bilayer.
There are other molecules embedded in the membrane.
cell membrane
protein
cholesterol
carbohydrate
chain
protein channel

9. Cell membranes are composed of two phospholipid layers.
The cell membrane is made of a phospholipid bilayer.
There are other molecules embedded in the membrane.
The fluid mosaic model describes the membrane.
cell membrane
protein
cholesterol
carbohydrate
chain
protein channel

10. About Cell Membranes (continued)
Structure of cell membrane
Lipid Bilayer -2 layers of phospholipids
Phosphate head is polar (hydrophilic; water loving)
Fatty acid tails non-polar (hydrophobic; water fearing)
Proteins embedded in membrane
Phospholipid
Lipid Bilayer

12. Cell membranes are composed of two phospholipid layers.
The cell membrane is selectively permeable.
Some molecules can cross the membrane while others cannot.

13. Cell membranes are composed of two phospholipid layers.
The cell membrane is selectively permeable.
Some molecules can cross the membrane while others cannot.

14. Chemical signals are transmitted across the cell membrane.
Receptors bind with ligands and change shape.
There are two types of receptors.

15. Chemical signals are transmitted across the cell membrane.
Receptors bind with ligands and change shape.
There are two types of receptors.
intracellular receptor

16. Chemical signals are transmitted across the cell membrane.
Receptors bind with ligands and change shape.
There are two types of receptors.
intracellular receptor
membrane receptor

17. What organelle allows molecules to pass from outside the cell to inside the cell?
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains

18. The Cell Membrane The Cell membrane consists of:
All cells are bound by a cell membrane.
The Cell membrane consists of:
Lipid bilayer [Phospholipid bilayer]
Proteins
Carbohydrates
Cholesterol

19. Membrane Structure

20. To Recap… Phospholipids are water resistant and flexible
Carbohydrates are like ID tags for the cell
Proteins are for stability and act like passageways for substances to enter and leave the cell.

21. The student is expected to: 4B investigate and explain cellular processes, including homeostasis, energy conversions, transport of molecules, and synthesis of new molecules and 9A compare the structures and functions of different types of biomolecules, including carbohydrates, lipids, proteins, and nucleic acid

22. KEY CONCEPT Materials move across membranes because of concentration differences.

23. Diffusion and osmosis are types of passive transport.
Passive transport does not require energy input from a cell.
Molecules can move across the cell membrane through passive transport.
There are two types of passive transport.
diffusion
osmosis

24. Diffusion and osmosis are types of passive transport.
Diffusion is when molecules move down a concentration gradient.
Movement is from a region of higher concentration to a region of lower concentration.

25. Diffusion
Diffusion: The movement of a molecule, or atom from an area of high concentration to an area of low concentration until equilibrium is reached
Equilibrium means equal concentrations on both sides of the membrane
This naturally occurs and normally no energy is required
Diffusion video

26. Diffusion and osmosis are types of transport.
Osmosis is the diffusion of water molecules across a semipermeable membrane.

27. Osmosis: the movement of water across a semi permeable membrane

29. Some molecules can only diffuse through transport proteins.
Some molecules cannot easily diffuse across the cell membrane.
Facilitated diffusion is diffusion through transport proteins.

30. Facilitated Diffusion
Movement of a molecule across a membrane when protein channels are required.
Sometimes molecules are too large to pass or they are charged and can’t pass through the membrane without help
When a protein channel helps a molecule this is called Facilitated diffusion
Protein channels are specific for one kind of molecule

31. Active Transport
Movement of molecules from low concentration to high concentration. (This is the opposite of diffusion)

32. Active Transport: Types
1) Molecular transport
Used for small ions such as calcium, potassium and sodium
Must pump ions across the membrane (This requires ENERGY!!)
Involves changes in protein shape

33. Diffusion and osmosis are types of passive transport.
There are three types of solutions.
isotonic
hypertonic
hypotonic

34. Hypotonic Solution
outside solution has a lower concentration of solute than inside the cell
(Higher concentration of water outside the cell)
Result:
Water will move into the cell
These red blood cells are in a hypotonic solution and have gained water

35. Hypertonic Solution
outside solution has a higher concentration of solute than inside the cell
(Lower concentration of water outside the cell)
Results:
Water moves out of the cell
These Red blood cells are in a hypertonic solution and have lost water

36. KEY CONCEPT Cells use energy to transport materials that cannot diffuse across a membrane.

37. Passive transport requires no energy from the cell.
Active transport is powered by chemical energy (ATP).
Active transport occurs through transport protein pumps.
Cells use active transport to maintain homeostasis.

38. Active Transport: Types
2) Endocytosis
For transport of larger molecules into the cell
Occurs with pockets of the cell membrane that fold into the cells creating a vacuole that is released into the cytoplasm
A vacuole is a bubble-shaped part of the cell used for storage

39. 2 types of Endocytosis
a) Phagocytosis: “cell eating”- cells take up particles and form a food vacuole

40. Pinocytosis: “Cell drinking”- cells take up liquid from the surrounding environment.

41. Exocytosis
Release of materials from the cell

42. Types of Cellular Transport
Animations of Active Transport & Passive Transport
high
low
Weeee!!!
Passive Transport
cell doesn’t use energy
Diffusion
Facilitated Diffusion
Osmosis
Active Transport
cell does use energy
Protein Pumps
Endocytosis
Exocytosis
high
low
This is gonna be hard work!!