2. The Cell Membrane “The Gatekeeper”

3. Overview Cell membrane separates living cell from nonliving surroundings Controls traffic in & out of the cell It is called selectively permeable b/c it allows some substances to cross more easily than others Made of phospholipids, proteins & other macromolecules

4. Intro video

5. What’s so important about the cell membrane? The cell membrane regulates what enters and leaves your cells. You eat food, your stomach breaks it into little pieces. The little pieces are brought to your cells Your cell membrane lets those little pieces into the cell. Without letting the bad stuff in.

6. Your body can use these little pieces of food for energy and to make things the body needs. Example: release energy in bonds of small sugars like glucose

7. Cell Membrane The cell membrane is can also be called the plasma membrane.

8. Structure of CM Phosopholipid bilayer Tough flexible barrier between the inside and outside of the cell. Protein molecules –Run completely through lipid layer –Form channels & pumps

9. Phospholipids Fatty acid Phosphate Fatty acid tails Are hydrophobic Phosphate group head Are hydrophilic Arranged as a bilayer I knew that!

10. carbohydrates The cell membrane also has carbohydrates that extend to the outside of the cell. This carb is involved in cell communication Its like a cell phone that allows the cells to communicate with each other. It extends off of a protein Not all proteins have them though.

14. Proteins in the CM

15. Movement across the Cell Membrane

16. Movement Though the CM The cell membrane is said to be Selectively Permeable This means it allows some things inside but other things are rejected. Things coming in and out of the cell are called transport.

17. Membrane Processes Types of Cell Membrane transport include: 1. diffusion (three types of diffusion) –A. passive transport –B. facilitated diffusion –C. Osmosis 2. active transport Its based on whether ATP is needed or not.

18. Diffusion Diffusion movement from high  low concentration

19. Diffusion Move from HIGH to LOW concentration –“passive transport” –no energy needed diffusion

20. Diffusion across cell membrane Cell membrane is the boundary between inside & outside… –separates cell from its environment IN food carbohydrates sugars, proteins amino acids lipids salts, O 2, H 2 O OUT waste ammonia salts CO 2 H2OH2O products cell needs materials in & products or waste out IN OUT What diffuses in and out of the cell?

21. Diffusion through phospholipid bilayer What molecules can get through directly? –fats & other lipids inside cell outside cell lipid salt aa H2OH2O sugar NH 3 What molecules can NOT get through directly? –polar molecules H 2 O –ions salts, ammonia –large molecules starches, proteins

22. Channels through cell membrane Membrane becomes semi- permeable with protein channels –specific channels allow specific material across cell membrane inside cell outside cell sugaraa H2OH2O salt NH 3

23. A. Passive Transport Passive transport: The movement of material across the cell membrane from areas of high concentration to areas of low concentration. cell does not need energy or ATP Passive transport is a type of diffusion that requires a cell membrane. Regular diffusion does not. http://videos.howstuffworks.com/hsw/23424-cell-diffusion-across- the-cell-membrane-video.htmhttp://videos.howstuffworks.com/hsw/23424-cell-diffusion-across- the-cell-membrane-video.htm

24. B. Facilitated Diffusion: Protein helpers DIFFUSE substances across the cell membrane FASTER than normal. –Proteins are specific to the substance they carry. –Still is diffusion, meaning it goes from high to low so no ATP is needed.

25. Facilitated Diffusion –no energy needed “The Bouncer” open channel = fast transport facilitated = with help high low

26. C. Osmosis Osmosis is the diffusion of water. Water is very important to life, so we talk about water separately Diffusion of water from high concentration of water to low concentration of water –across a semi-permeable membrane

27. Concentration of water Direction of osmosis is determined by comparing the concentration of solutes dissolved on each side of the membrane. –Hypertonic - more solute, less water –Hypotonic - less solute, more water –Isotonic - equal solute, equal water hypotonichypertonic water net movement of water

28. Hypertonic: "HYPER" means more –there are more solutes (salt) outside the cell than inside –Osmotic pressure causes the water to be sucked out. –Plant cells: vacuole loses water; the cells shrink, causing wilting. –In animal cells, cells also shrink. –In both cases, the cell may die. –Water always goes in the direction of the higher solute. –Higher solute=less water

29. Hypotonic: HYPO means less –there are less solutes (salt) outside the cell than inside –Osmotic pressure causes, water to move into the cell. –The cell will gain water and grow larger. –In plant cells, vacuoles will fill –the cell wall keeps the plant from bursting –In animal cells, the cell is in danger of bursting,

30. Isotonic solution: concentration of solute (salt) is equal on both sides, the water moves in and out at an equal rate Cell size will not change. "ISO" means the same

31. Remember During osmosis, the cell is permeable to the water (water can pass) but not the solutes (dissolved substances) such as salt and sugar. Water moves across the membrane until an equilibrium is reached Water concentration is equal on both sides of cell membrane. The salts and sugars do not diffuse

32. osmosis

33. 2.active transport: molecules move from lower to higher concentration. lower higher Does not naturally occur. http://videos.howstuffworks.com/hsw/23425-cell-active-transport-and-the-cell- membrane-video.htm http://videos.howstuffworks.com/hsw/14765-simply-science-active-transport- video.htm

34. 2. Active Transport “The Doorman” Cells move molecules against concentration gradient –Uses a protein “pump” which…. –“costs” energy = ATP ATP low high

35. Transport summary simple diffusion facilitated diffusion active transport ATP

36. Cell membrane and homeostasis http://videos.howstuffworks.com/hs w/23423-cell-homeostasis-and-the- cell-membrane-video.htmhttp://videos.howstuffworks.com/hs w/23423-cell-homeostasis-and-the- cell-membrane-video.htm

37. How about large molecules? Macromolecules are toooooo big to diffuse. They must be moved into the cell through vesicles & vacuoles A. endocytosis phagocytosis = “cellular eating” pinocytosis = “cellular drinking” B. exocytosis exocytosis

38. Endocytosis phagocytosis pinocytosis fuse with lysosome for digestion non-specific process

39. review

40. Fluid mosaic model This model of the cell membrane is called the fluid mosaic model. Do you know what a mosaic is? Think about art.

41. Mosaic A piece of artwork made up of little pieces of tile lying close together but not connected. It gives the illusion that it is all one piece but it is not. Why is the cell membrane considered a mosaic model?

44. Because the pieces of the cell membrane are not actually attached, though the appear to be.

45. The phospholipids are not attached to each other. The proteins are not attached other.

46. Cell communication Cell-to-Cell communication is important for multicellular organisms. The billions of cells of a human or an oak tree must communicate in order to develop from a fertilized egg and then survive and reproduce in turn..

47. receptors Receptor molecules play an important role in the interactions and communication between cells. Two primary agents of cellular communication are hormones and chemicals produced by other cells The chemical has instructions and tells the cell what is needed to be done.. Receptor molecule Chemical released by another celll

48. Blocked signal If those hormone signals are blocked, cellular communication is stopped and the organism’s homeostasis or health is affected. Its like when you are out of range and your cell phone cannot get a signal. You have no idea the other person is even trying to call you

49. Receptors are specific Unlike your cell phone, each receptor is specific to a a specific type of signal. That’s kinda like trying to log onto someone’s wifi and you don’t have the password. You cant acess the info without the correct password The cell cant access just any chemical signal. It must fit the receptor. Each cell has millions of receptors.

51. Please explain how chemical signals work __________________________ _________________________ __________________________ _________________________ __________________________

52. Cell receptor animaton