1. BELL WORK: Answer the following questions on your bell work page: 1.A scientist finds a unicellular organism. He can see its DNA is free-floating in the center of the cell. What kind of cell is this, and how do you know? 2.Which organelles help produce and move proteins in a cell? (hint: there are THREE)

2. Today’s Standard (B.4B): Investigate and explain cellular processes including…transport of molecules Today’s Essential Question: How do molecules move in a cell?

3. Atom Molecule Organelle Cell *Life* Tissue Organ Organ System Organism Does not have Does Have

4. CELL MEMBRANE: thin, flexible barrier surrounding all cells

5. What is the cell membrane’s function (job)? (2 things)

6. Two main functions: 1) regulate what enters (food, water, & oxygen) & leaves (waste) 2) protection & support

7. What is the cell membrane composed (made) of? (3 types of molecules)

8. LIPIDS: main component of cell membrane – double layer called the lipid bilayer or phospholipid bilayer – hydrophobic and hydrophilic tails (hydro=water)(phobic=fear) (phile=love) DRAW THIS!

9. Allot like a basketball

10. PROTEINS: embedded into the lipid bilayer – Form channels or pumps (pathways) to help move large molecules

11. CARBOHYDRATES: attached to proteins outside of the bilayer – allow cells to communicate with each other carbohydrates

12. How do molecules move in or out through the cell membrane?

13. Why does food coloring spread out in water?

14. In a solution, particles are constantly moving. They collide with one another and spread out randomly.

15. DIFFUSION: particles move from an area of HIGH concentration to an area of LOW concentration

16. CONCENTRATION: the amount of solute (stuff) dissolved into a solvent (liquid) KOOL-AID is the solute WATER is the solvent CONCENTRATION is how much Kool-Aid you put in

17. CONCENTRATION GRADIENT: a difference between two concentrations If diffusion is going from high concentration to low concentration, what direction is it moving on the concentration gradient? High Concentration Low Concentration

18. EQUILIBRIUM: the concentration of a solute is the same throughout a system – particles continue to move – the goal of diffusion!

19. Diffusion does NOT require energy!!

20. The rate (speed) at which molecules pass through a membrane depends on its permeability.

21. PERMEABLE membranes allow all substances to pass through IMPERMEABLE membranes allow no substances to pass through

22. Biological (cell) membranes are SELECTIVELY permeable – Some substances can pass through, while others cannot

23. OSMOSIS: diffusion of water through a selectively permeable membrane – does NOT require energy!