1. Ch. 7 Cellular Basis of Life
Modified & Adapted from

2. Key Concepts: Chapter 7 & Chapter 8
1. If the cell were a city, what structures or buildings would the following be?
Nucleus, Mitochondrion, Plasma membrane, Ribosomes
2.  Name 2 differences between plant and animal cells.
3. What are membrane-bound structures in eukaryotic cells with specialized functions called?
4. Name 2 characteristics of prokaryotes.
5. Name a kingdom in which the members are eukaryotes. 
6. If you put a piece of lettuce in a dish of saltwater, what will happen to the lettuce cells?
7. What is the function of the plasma membrane?
8. Give an everyday example of passive transport.
9. What process does the decrease in surface area to volume ratio cause to slow down so much that the cell can’t function?

3. PLASMA MEMBRANE

4. PLASMA MEMBRANE Controls what gets in/out of cell
Cell must maintain a stable internal environment regardless of the external environment

5. Changes in external & internal environment a cell must deal with :
1. concentration of food
2. concentration of dissolved substances
3. concentration of waste material

6. TEM picture of a real cell membrane.
About Cell Membranes
All cells have a cell membrane
Functions:
Controls what enters and exits the cell to maintain an internal balance called homeostasis
Provides protection and support for the cell
TEM picture of a real cell membrane.

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

8. Fluid Mosaic Model of the cell membrane
Polar heads love water & dissolve.
Membrane movement animation
Non-polar tails hide from water.
Carbohydrate cell markers
Proteins

9. About Cell Membranes (continued)
4. Cell membranes have pores (holes) in it
Selectively permeable: Allows some molecules in and keeps other molecules out
The structure helps it be selective!
Pores

10. Structure of the Cell Membrane
Outside of cell
Carbohydrate
chains
Proteins
Lipid
Bilayer
Transport
Protein
Phospholipids
Inside of cell
(cytoplasm)
Animations
of membrane structure

11. 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!!

12. Passive Transport cell uses no energy molecules move randomly
Molecules spread out from an area of high concentration to an area of low concentration.
Three types:

13. 3 Types of Passive Transport
Diffusion
Facilitative Diffusion – diffusion with the help of transport proteins
Osmosis – diffusion of water

14. Simple Diffusion Animation
Diffusion: random movement of particles from an area of high concentration to an area of low concentration.
(High to Low)
Diffusion continues until all molecules are evenly spaced (equilibrium is reached)-Note: molecules will still move around but stay spread out.

15. 1. Diffusion
Dialysis tubing is a porous membrane that only lets small molecules (like water, oxygen, carbon dioxide, and glucose) pass through, and is commonly used to help filter out the metabolic wastes from the blood of people with bad kidneys (a process called “kidney dialysis”). We can predict that small molecules like glucose will pass through this membrane, but that large molecules like starch will not be able to pass through the membrane.

16. Facilitated diffusion (Channel Protein) Diffusion (Lipid Bilayer)
2. Facilitated diffusion: diffusion of specific particles through transport proteins found in the membrane
Transport Proteins are specific – they “select” only certain molecules to cross the membrane
Transports larger or charged molecules
Facilitated diffusion (Channel Protein)
Diffusion (Lipid Bilayer)
Carrier Protein

17. 2. Facilitated Diffusion (cont)
Glucose
molecules
Cellular Transport From a-
High
High Concentration
Channel Proteins animations
Cell Membrane
Low Concentration
Protein
channel
Low
Transport Protein
Through a 
Go to Section:

18. 3. Osmosis
Osmosis animation
3.Osmosis: diffusion of water through a selectively permeable membrane
Water moves from high to low concentrations
Water moves freely through pores.
Solute (green) to large to move across.

19. Active Transport cell uses energy
actively moves molecules to where they are needed
Movement from an area of low concentration to an area of high concentration
Three Types:

20. Types of Active Transport
Sodium Potassium Pumps (Active Transport using proteins)
1. Protein Pumps -transport proteins that require energy to do work
Example: Sodium / Potassium Pumps are important in nerve responses.
Protein changes shape to move molecules: this requires energy!

21. Types of Active Transport
2. Endocytosis: taking bulky material into a cell
“cell eating”
Uses energy
Cell membrane folds in around particle & forms a vacuole
Pinocytosis-liquids
Phagocytosis-solids
This is how white blood cells eat bacteria!

22. Types of Active Transport
3. Exocytosis: Forces material out of cell in bulk
membrane surrounding the material fuses with cell membrane
Cell changes shape – requires energy
EX: Hormones or wastes released from cell
Endocytosis & Exocytosis animations

23. Effects of Osmosis on Life
Osmosis- diffusion of water through a selectively permeable membrane
Water is so small and there is so much of it the cell can’t control it’s movement through the cell membrane.

24. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions
Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water)
Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

25. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions
Hypertonic Solution
Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water)
Elodea water plant
shrinks
Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!

26. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions
Isotonic Solution
Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell.
Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

27. What type of solution are these cells in?B C A
Hypertonic
Isotonic
Hypotonic

28. How Organisms Deal with Osmotic Pressure
Paramecium (protist) removing excess water video
Bacteria and plants have cell walls that prevent them from over-expanding. In plants the pressure exerted on the cell wall is called tugor pressure.
A protist like paramecium has contractile vacuoles that collect water flowing in and pump it out to prevent them from over-expanding.
Salt water fish pump salt out of their specialized gills so they do not dehydrate.
Animal cells are bathed in blood. Kidneys keep the blood isotonic by remove excess salt and water.

29. Cell Growth and Reproduction
A. Cell Size Limitations
1. Diffusion, method of obtaining glucose and oxygen and excreting waste, is much more efficient over short distances.

30. 2. Limit to how quickly information for creating proteins can be copied from nucleus and made in the cytoplasm

31. 3. Surface area to volume ratio
a. As cell size increases, volume increases much faster than surface area.
b. Not enough plasma membrane for oxygen, nutrients, and waste to diffuse.
cellsalive.com

32. THE END