Cellular Processes

1. Cellular Processes

2. Day 1 Write in your agenda: I can describe different cellular processes and how they are important for homeostasis (balance) of all organisms.

3. LAB VOCAB: What is a SOLUTE and a SOLVENT? Using the visual, answer the above question in your notes and be ready to discuss.

4. Solute vs. Solvent Solute: The substance being dissolved Solvent: a liquid capable of dissolving another substance (Water is the universal solvent) Remember that most cells live in a liquid environment. Since the liquid inside the cell and the liquid outside the cell usually have a bunch of other stuff dissolved in them, we refer to these liquids as solutions.

5. Critical Thinking Activator Sea water has a HIGHER concentration of SOLUTES than do human body cells. Why might drinking large amounts of SEA WATER be DANGEROUS for the human body’s equilibrium? (Be ready to discuss in a moment.)

6. ANSWER: • The solutes in sea water would make the solution outside the body cells more concentrated. Water would then diffuse out of the cells, causing them to shrink and possibly die.

7. All living things must be able to obtain food and eliminate waste. Cells need to perform these tasks in order to maintain homeostasis. This is the tendency of a system to maintain internal stability or equilibrium. Homeostasis is maintained by the cell (plasma) membrane controlling what substances enter and leave the cell.

8. Chillin’ at the Beach Demonstration (passive transport) BrainPop: Passive Transport

9. Passive Transport • A process that does not require energy to move molecules from a HIGH to LOW concentration across the cell membrane • Types of Passive Transport • Diffusion • Osmosis

10. Diffusion video clip must click play http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

11. outside of cell inside of cell • Diffusion is the movement of small particles across a selectively permeable membrane, like thecellmembrane, until equilibrium is reached. • These particles move from an area of high concentration to an area of low concentration.Diffusion is driven entirely by the constant motion of molecules..

12. Diffusion HIGH to LOW concentration

13. Osmosis is the diffusion of waterthrough a selectively permeable membrane like the cellmembrane Water diffuses across a membrane from an area of high concentration to an area of low concentration. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html Semi-permeable membrane is permeable to water, but not to sugar

15. Osmosis • The diffusion of Water! Because so much water, oxygen, and carbon dioxide are constantly passing into and out of a cell, it would totally exhaust the cell if the cell had to use its own stored energy (in the mitochondria) for osmosis. Luckily for the cell, osmosis is a type of passive transport. This means that the cell exerts no energy during osmosis.

16. Check for Understanding 1. What is osmosis? 2. What type of transport takes place during osmosis? 3. How much energy does the cell use during this type of transport? 4. The process of particles to spread out is known as __________________.

17. Check for Understanding Osmosis is the diffusion of water through a selectively permeable membrane. 2. What type of transport takes place during osmosis? passive 3. How much energy does the cell use during this type of transport? none 4. The process of particles to spread out is known as diffusion.

18. Day 2 Write in your agenda: I can describe different cellular processes and how they are important for homeostasis (balance) of all organisms.

19. Critical Thinking Activator A gelatin block is prepared with a CHEMICAL INDICATOR that turns PINK in the presence of a BASE. The block is enclosed in a MEMBRANE and placed in a beaker of AMMONIUM HYDROXIDE solution. After 30 minutes, the block begins to TURN pink. What may have occurred to PRODUCE this observable result? (Be ready to discuss in a moment.)

20. ANSWER: Ammonium hydroxide is small enough to diffuse through the membrane, and because it’s a base, it turns the indicator pink.

21. When the concentration of the dissolved particle (indicated by a %) is greater outside the cell than it is inside the cell, it is a hypertonic solution. The prefix hyper means “excessive” or “above normal.” When the concentration of the dissolved particle (indicated by a % is greater inside the cell than it is outside the cell, it is a hypotonic solution. The prefix hypo means “under” or “below normal.” Think of (if you dare) a hypodermic needle. Needles go “under” or “below” your skin. Since water will want to move into the cell, think of the needle injecting it in in a hypotonic situation.

22. So, how can this affect a cell then?

23. In a hypotonic situation, cells can swell so much with water that they burst. Farmers often fear this will happen after a heavy rain. Fruit crops like tomatoes often burst if they get too much water.

25. Hypotonic

29. Hypertonic

33. When the concentration of the solution inside and outside the cell is the same, the cell has reached equilibrium, and the solution is called an isotonicsolution. Cells like to be balanced. When they are balanced, water flows in and out of the cell at an equal rate. Cells are happy.

34. Equilibrium (RESULT of diffusion) • UNIFORM distribution over time.

35. Complete Passive Transport Pocket Card

36. Day 3 Write in your agenda: I can describe different cellular processes and how they are important for homeostasis (balance) of all organisms.

37. (1) Contractile Vacuoles (found in freshwater protists) • Collects and PUMPS out EXCESS water using NRG. (i.e., NOT osmosis, pumping AGAINST gradient)

39. Critical Thinking Activator Sometimes water SEEPS through the concrete WALL of a basement after a heavy rain, and the homeowner must REMOVE it with a sump pump. HOW can this situation be compared to the action of a unicellular organism that inhabits a freshwater pond?

40. ANSWER: The organism’s selectively permeable membrane can be compared to the porous concrete wall; water crosses both barriers. A contractile vacuole removes water from the organism using energy supplied by the organism, just as the sump pump removes water using electrical energy.

41. Chillin’ at the Beach Demonstration (active transport) BrainPop: Active Transport

42. Active transport is the movement of molecules from a LOW to HIGH concentration. Energyis required as molecules must be pumped against the concentration gradient. .

44. Endocytosis When large particles of food are taken into the cell, it is called endocytosis. The prefix endo- means “to go into.” Think ENdo-Enter. • Example: White Blood Cells, which are part of the immune system, surround and engulf bacteria by endocytosis.

45. Steps of Endocytosis During endocytosis, the cell membrane folds inward and fuses together. This surrounds the substance in a pocket. The pocket pinches off inside of the cell, forming a vesicle. The vesicle fuses with a lysosome or similar vesicle. Then, enzymes break down the membrane AND the contents inside!

46. Exocytosis • When the cell releases large bundles of waste from the cell, that is called exocytosis. The prefix exo- means “out of” or “outer.” Think Exo-Exit.

47. Steps of Exocytosis The cell forms a vesicle around material that needs to be expelled from the cell. The vesicle is transported to the cell membrane. The vesicle membrane fuses with the cell membrane and releases the contents from the cell.

48. Exocytosis Inside of the cell Outside of the cell

49. Diffusion Movement of small molecules across the membrane No energy, High to low concentration Move molecules in and out of cell Active Transport Uses energy while moving molecules across the cell, moves from low to high concentration Osmosis Movement of water across the membrane

50. Complete Active Transport Pocket Card