1. Cell Structure & Function
Unit 2
Cell Structure & Function
Cell Organelle structure/relative location/function
3 Cellular Processes:
-Diffusion/ Osmosis
-Cellular Respiration
-Kreb’s Cycle
-Photosynthesis

2. Cell Membranes Osmosis and Diffusion

3. Functions of Membranes
1. Protect cell
2. Control incoming and outgoing substances
3. Maintain ion concentrations of various substances
4. Selectively permeable - allows some molecules in, others are kept out

4. Phospholipid Bilayer

5. Fluid Mosaic Model

6. Blood-Brain Barrier
Allows some substances into the brain, but screens out toxins and bacteria
Substances allowed to cross include:
water, CO2, Glucose, O2, Amino Acids, Alcohol, and antihistamines. HIV and bacterial meningitis can cross the barrier.

7. Solutions Solutions are made of solute and a solvent
Solvent - the liquid into which the solute is poured and dissolved. We will use water as our solvent today.
Solute - substance that is dissolved or put into the solvent. Salt and sucrose are solutes.

8. Methods of Transport Across Membranes
1. Diffusion
2. Osmosis
3. Facilitated Diffusion
4. Active Transport

9. Methods of Transport Across Membranes
1. Diffusion -passive transport - no energy expended
2. Osmosis - Passive transport of water across membrane
3. Facilitated Diffusion - Use of proteins to carry polar molecules or ions across
4. Active Transport- requires energy to transport molecules against a concentration gradient – energy is in the form of ATP

10. Diffusion
Movement of molecules from an area of high concentration to an area of low concentration.
Movement from one side of a membrane to another, un-facilitated

11. Movement of Substances
Diffusion
Osmosis

12. Lets Recap from Chemistry…
3 particle states of matter
What is the particle arrangement and motion?
Diffusion
Solid
Liquid
Gas

13. Diffusion Definition: 1)The net movement of particles
2)from a region of higher concentration
3)to a region of lower concentration,
4)down the concentration gradient.
High concentration
Low concentration

14. Diffusion in liquid state
: Ink dye
: Water molecules

15. Diffusion in liquid state
: Ink dye
: Water molecules

16. Diffusion in gaseous state
: Perfume molecules
: Air molecules

17. Diffusion in gaseous state
: Perfume molecules
: Air molecules

18. Net Movement
Note: This barrier does not illustrate a partially permeable membrane.

19. Net Movement

20. Equilibrium
When particles reaches an equilibrium, does the particles stop moving?
Hint: Particles move in a random and dynamic motion.

21. Concentration Gradient
The concentration difference between regions of high concentration and low concentration.
High concentration gradient
Low concentration gradient
Down the concentration gradient

22. Concentration Gradient
Which slide will allow you to go down faster? A B
Answer: A

23. Movement of Substances
includes
Osmosis
Diffusion
definition
Net movement of particles from a region of high concentration to a region of low concentration, down the concentration gradient.
Key Ideas:
1) Liquid/ Gas particles move from region of high concentration to low concentration
2) Movement of particles is random and dynamic in equilibrium (net)
3) Concentration gradient
4) Examples of diffusion

24. Osmosis Definition: The movement of water molecules
through a partially permeable membrane
from a solution of high water potential,
to a solution of lower water potential.
: sucrose
:water molecules
Partially permeable membrane

25. Partially Permeable Membrane
Allows some substances to pass through but not others.
Unequal concentration of ions in both sides of the membrane
Eg: Cell membrane in plant and animal cells.
Allows both the solvent (water) and the solutes ( dissolved substances to pass through)
Equal concentration of all ions in both sides of the membrane.
Eg: Cell Wall of plant cells

26. The movement of water molecules through a partially permeable membrane
Only water molecules passes through the partially permeable membrane (sucrose solution too big to pass through the partially permeable membrane).
: sucrose
:water molecules
Partially permeable membrane

27. Apply the knowledge, young humans.
What happens if a man, lets call him… Shyle, is lost on the ocean and, in order to save his life, drinks the ocean water?

30. K...So… What Do I need to know?
Cell membrane structure
Know the difference between active/passive transport
Know the difference between pinocytosis/ phagocytosis, and, endocytosis/extocytosis
Understand diffusion and osmosis
Know what a concentration gradient is and how it works