1. LECTURE 9: CYTOLOGY The Cell Membrane and Cell Transport

2. Describe the structure of cell membranes
Compare Active and Passive Transport
Explain Osmosis
Compare hypertonic, hypotonic, and isotonic solutions

3. Topic 1: Cell Membrane Components

4. Phospholipid Bilayer
Phosphate head
Fatty acid tails
Hydrophilic = water loving Hydrophobic = water fearing

5. Proteins Integral Transmembrane Peripheral
found through the inner bilayer - have hydrophobic regions (towards inside of cell)
Transmembrane
found throughout the entire bilayer
Peripheral
found only “outside” bilayer

6. Carbohydrates
Glycolipids and Glycoproteins serve as recognition sites for other cells

7. Topic 2: Cell Transport-Passive Transport

8. Cell Transport: Two types: Active and Passive Passive Active
processes include different types of diffusion
Active
processes require the input of energy

9. Passive Transport: Diffusion
Diffusion - the process of random movement toward a state of equilibrium
The net movement from regions of greater concentration to regions of lesser concentration
Example: Drop of ink in water

10. Diffusion Rate How fast can a substance diffuse?
The diameter of the molecules/ions
Temperature of solutions
Electric charge of material diffusing
Concentration gradient - change in concentration with distance in a given direction

12. Cell Transport Across a Membrane
Permeable
solutes cross membrane more easily
SEMI-permeable
membrane only allows certain solutes to cross membrane
Impermeable
solutes CANNOT cross membrane

13. Diffusion across cell membrane
Diffusion and Facilitated Diffusion of molecules.

14. Osmosis Osmosis is the diffusion of water across a membrane
Movement of water molecules from regions of higher water potential to regions of lower water potential across a semi-permeable or selectively permeable membrane.

15. Carrot Demo
What will happen to a carrot if place in distilled water, salt water, and sugar water?
Write down your hypothesis in your notes.

16. Types of Solutions Hypertonic solutions
cell environment has a higher concentration of solutes than inside the animal or plant cell.
Hypotonic solutions
cell environment has a lower concentration of solutes than inside the animal or plant cell.
Isotonic solutions
have equal (iso-) concentrations of substances. Water potentials are thus equal, although there will still be equal amounts of water movement in and out of the cell, the net flow is zero.

17. Crenation
Lysis
Red Blood Cells

18. Plant Cells

19. Topic 3: Cell Transport- Active Transport

20. Active Transport

21. Active Transport Active Transport
transport of molecules/ions across the membrane which requires energy.
Transported AGAINST the concentration gradient
Example: H+ ion pump and Na+ K+ pump

22. Transport of Large Material
Endocytosis
Into cell
Exocytosis
Out of cell

23. Types of Materials Transported
Phagocytosis = “cell eating”
Pinocytosis = “cell drinking”

24. Lysosomes
Lysosomes use digestive enzymes to break down vesicle