1. 7-3
Cell Boundaries

2. Cell Membrane Cell membrane =
controls what enters and leaves the cell
provides protection and support
Receives chemical signals
All cell membranes are made up of a double layer known as a lipid bilayer.

3. The Structure of the Cell Membrane
Section 7-3
Outside
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains
To concept map

4. Cell Walls Cell wall = provides support and protection for the cell
the cell wall is found in plant and fungi cells not animal cells

5. Measuring concentration
The cytoplasm of a cell contains many different substances in water
The substances dissolved in the solution are called solutes
The concentration of a solution is the mass of the solute in the volume of solution
Example: 12 grams of salt in 4 liters of water is 12g/3L
The concentration is 3g/L

6. Diffusion In a solution molecules move constantly and randomly
Diffusion = molecules tend to move from an area of high concentration to an area of low concentration to spread out
When the concentration in the solution is the same throughout it is at equilibrium
Diffusion happens without having to use energy

7. Osmosis
Many substances can diffuse across the membrane bus some are too large or strongly charged and cannot cross.
Water moves easily across the membrane
Osmosis = is the diffusion of water through a selectively permeable membrane
Water will move across the membrane until equilibrium is reached, at that point the concentration of water and solute will remain the same. This will mean they are isotonic

8. Isotonic = same strength (equal amounts)
Hypertonic = above strength (more solute)
Hypotonic = below strength (less solute)

9. Effects of Osmosis on Cells

10. Facilitated Diffusion
Some molecules, such as Glucose, move across the cell membrane through protein channels
Facilitated diffusion= is when a protein in the cell membrane helps a molecule move across it

11. Facilitated Diffusion
Section 7-3
Glucose
molecules
High
Concentration
Cell
Membrane
Low
Concentration
Protein
channel
To concept map

12. Active Transport
Active transport is when a cell uses energy to “pump” molecules across the membrane against the concentration gradient
Moving molecules from a low concentration to a high concentration
Requires energy!!

13. Active Transport Molecule to be carried Section 7-3 Energy Molecule
being carried
Energy
Section 7-3
Active Transport
To concept map

14. Endocytosis
Endocytosis = is the process of taking material into the cell by means of infoldings, or pockets of the cell membrane
Endo = In

15. Endocytosis – two types
Phagocytosis: extensions of cytoplasm surround a particle and package it within a food vacuole
Pinocytosis: tiny pockets form around the cell membrane, fill with fluid, and pinch off to form vacuoles

16. Exocytosis
exocytosis: the membrane of the vacuole surrounding the material fuses with the cell membrane, forcing the contents out of the cell.
Exo = Out