1. Transport of Molecules in a Cell

2. Terms to Know
SOLUTE: refers to the substance that is to be dissolved (Salt, Sugar)
SOLVENT: responsible for dissolving the solute (Water)
SOLUTION: Solvent and solute after combining together
ECF: Extracellular Fluid. Surrounds all living cells
CONCENTRATION: mass of solute dissolved in the solvent
SEMI-PERMEABLE (SELECTIVELY-PERMEABLE): a membrane that allows only some substances in or out

3. Selectively Permeable Membrane

4. Transportation of Molecules
Passive Transport
Movement of molecules across a semi-permeable membrane with the gradient
3 types: Osmosis,Diffusion +
Facilitated Diffusion
Movement of molecules across a semi-permeable membrane with a protein
NO ENERGY required
Active Transport
Movement of molecules across a semi-permeable membrane against a concentration gradient with a protein
ENERGY required

5. Diffusion
Solute molecules moving from an area of high concentration to an area of low concentration
Random motion drives diffusion
Movement is based on kinetic energy (speed), charge, and mass of molecules
Equilibrium is reached when there is an even distribution of solute molecules
(water) 2 3 1 4

6. Equilibrium Reached
Low Concentration
High Concentration

7. Osmosis [concentration]
Diffusion of water through a semi-permeable membrane
Permeable to solvents (WATER), but not to large molecules
High [water] to low [water]
[concentration]
Dissolved molecules (i.e. glucose, starch) are called solutes
REMEMBER:
Water = solvent Glucose, Starch, Salt = solutes

8. Effect of Water on Cells
Hypertonic Environment
High [solute], low [water]
Isotonic Environment
[water] = [solute]
Hypotonic Environment
High [water], low [solute]

9. Osmosis Sucrose will not move but water will

11. Dialysis Bag Experiment
Semi-permeable membrane
Water, glucose, & starch
What passes through the dialysis bag?
Glucose (Benedict’s Test)
Starch (Iodine Solution)
Time Course Experiment
Every 10 minutes, measure the amount of glucose & starch present in the beaker
Iodine
Glucose
Starch
Dialysis bag

12. Osmosis in Living Cells
Cellulose in cell wall
plasmolyzed flaccid
Normal
turgid

13. RED BLOOD CELLS

14. Osmosis in Plant Cells Plasmolysis
Hypertonic
Plasmolysis
Observe Elodea leaves via a wet mount of the sample
10% NaCl
Distilled water
Hypotonic

15. Recall the Cell Membrane

16. Proteins in the Plasma (cell) Membrane

17. Proteins are Specific to certain Solutes

18. Active Transport

19. ENDOCYTOSIS
The general term for bringing bulk chemicals into a cell is endocytosis (endo = inside); the general term for bringing bulk chemicals out of a cell is exocytosis (exo=outside).
Moving material into the cell by endocytosis involves the pinching in of a portion of the cell membrane around the material to be transported into the cell. The pinched-in portion eventually breaks free from the cell membrane and forms a vesicle in the cytoplasm.

20. Homework Complete your Cheek Cell & Elodea Cell mini-lab
Study for your Microscope quiz
Answer questions on p.25 Q.1-19
 Next topic: Cell cycle & cell division