1. Cell Boundaries
Objective: 4B – Investigate and explain cellular processes, including homeostasis, energy conversions, transport of molecules, and synthesis of new molecules

2. Chp. 7, Section 2 & 4 – Cell Boundaries
Animal cell
Plant cell
Cell / Plasma
Membrane
Cell walls make up the bulk, roughage, or fiber of our diet, material that we do not have enzymes to digest. (review ENZYMES orally)
Cell Wall – provides support & protection, usually made of tough fibers

3. 1. The Cell Membrane
Complex barrier separating the cell from it's external environment
Holding cytoplasm within cells
Regulating substances entering and exiting cells
Recognizing other cells
Is arranged in a double layer
called a Lipid Bilayer –
Made up of Phospholipids
(a phosphate group
& 2 fatty acids)

4. 1. The Cell Membrane "Selectively Permeable" membrane that regulates
(like a gate) what passes into and out of the cell

5. 1. The Cell Membrane Cell Membranes are FLUID
Lipids and Proteins of the Cell Membrane are always in motion

6. 1. The Cell Membrane Membrane Proteins
PROTEIN MOLECULES are EMBEDDED in the Lipid Bilayer
HELP to MOVE substances that are large or charged (ions) INTO and OUT of the Cell

7. 1. The Cell Membrane
Often have carbohydrates attached to them to serve as I.D. badges that allow cells to recognize each other

8. 1. The Cell Membrane Diffusion
Movement of particles from an area of high concentration to an area of low concentration (no energy required)
Osmosis
Diffusion of water through a selectively permeable membrane

9. 3 different types of Osmosis

10. 3 different types of Osmosis
Isotonic
The concentration of solutes is the same inside and outside the cell
Water moves in and out
Hypertonic
Solution has a higher solute concentration than the cell
Water moves out
Hypotonic
Solution has a lower solute concentration than the cell
Water moves in

11. Tip to remember: Salt Sucks!
Water moves toward the more salty area.
H2O
Hypertonic Solution

12. 1. The Cell Membrane Facilitated Diffusion / Passive Transport
Uses proteins to move molecules through a cell membrane along the concentration gradient (no energy required)

13. 1. The Cell Membrane Active Transport
Uses proteins to move molecule against the concentration gradient
Requires energy

14. Exocytosis and Endocytosis
Exocytosis – process of a cell releasing materials
Endocytosis – process of cell taking materials in
Exocytosis

15. Animal cell Plant cell Cell / Plasma Membrane
All we have been talking about today happens with the outer boundary of a cell.

16. Practice Question
Which cell process will move substances against a concentration gradient? [NC08 EOC] A
diffusion B
facilitated diffusion C
osmosis D
passive transport E
active transport
Requires ENERGY

17. Practice Question
What cell membrane structure allows bigger molecules to cross over and also serves as an attachment site for the cytoskeleton?
Carbohydrate
Phospholipids
Cholesterol
Protein

18. What kind of passive transport is shown in the picture?
Diffusion
Osmosis
Facilitated diffusion
Active transport