Cellular Transport Notes

1. Cellular Transport Notes

2. About Cell Membranes • All cells have a cell membrane • Functions: • Controls what enters and exits the cell to maintain an internal balance called homeostasis • Provides protection and support for the cell

3. About Cell Membranes (continued) • Structure of cell membrane Lipid Bilayer -2 layers of phospholipids • Phosphate head is polar (water loving) • Fatty acid tails non-polar(water fearing) • Proteins embedded in membrane • Steroids and cholesterol are embedded within the cell membrane.They provide support and flexibility. Phospholipid Lipid Bilayer

4. Fluid Mosaic Model of the cell membrane States that the membrane is in constant motion Polar heads love water & dissolve. Non-polar tails hide from water. Carbohydrate cell markers Proteins

5. About Cell Membranes (continued) • 4. Cell membranes have pores (holes) in it • Selectively permeable: Allows some molecules in and keeps other molecules out • The structure helps it be selective! Pores

6. Cell Membrane

7. Cholesterol in the Membrane

8. Structure of the Cell Membrane Outside of cell Carbohydrate chains Proteins Lipid Bilayer Transport Protein Phospholipids Inside of cell (cytoplasm) Animations of membrane structure Go to Section:

9. Cell Transport • There are three types of cellular transport • Passive Transport • Active Transport • Cytosis

10. Animations of Active Transport & Passive Transport Weeee!!! high low This is gonna be hard work!! high low Types of Cellular Transport • Passive Transport cell doesn’t use energy • Diffusion • Facilitated Diffusion • Osmosis • Active Transport cell does use energy • Protein Pumps • Endocytosis • Exocytosis Cytosis

11. Simple Diffusion Animation Passive Transport:1. Diffusion • Diffusion: random movement of particles from an area of high concentration to an area of low concentration. (High to Low) • Diffusion continues until all molecules are evenly spaced (equilibrium is reached)-Note: molecules will still move around but stay spread out. http://bio.winona.edu/berg/Free.htm

12. What determines the rate of diffusion?There 4 factors: • The steepness of the concentration gradient. The bigger the difference between the two sides of the membrane the quicker the rate of diffusion. • Temperature. Higher temperatures give molecules or ions more kinetic energy. Molecules move around faster, so diffusion is faster. • The surface area. The greater the surface area the faster the diffusion can take place. This is because the more molecules or ions can cross the membrane at any one moment. • The type of molecule or ion diffusing. Large molecules need more energy to get them to move so they tend to diffuse more slowly. Non-polar molecules diffuse more easily than polar molecules because they are soluble in the non polar phospholipid tails.

13. Passive Transport • The diffusion of water is called OSMOSIS.

14. Passive Transport - Osmosis A good way to remember which way water will move is to remember that the water will ALWAYS move TOWARDS the solutes (salt).

15. Passive Transport: 3. Osmosis Osmosis animation • 3.Osmosis:diffusion of water through a selectively permeable membrane • Water moves from high to low concentrations • Water moves freely through pores. • Solute (green) to large to move across.

16. Passive Transport • We have special names for the different types of situations where osmosis occurs in cells.

17. Passive Transport • We have special names for the different types of situations where osmosis occurs in cells.

18. Hypotonic Solution Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

19. Hypertonic Solution Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) shrinks Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!

20. Isotonic Solution Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

21. What type of solution are these cells in? B C A Hypertonic Isotonic Hypotonic

22. Summary • Isotonic Solutions are those where the concentration of the solution EQUALS the concentration of the cell. • Hypertonic Solutions are those where the concentration of the solution is MORE than the concentration of the cell. • Hypotonic Solutions are those where the concentration of the solution is LESS than the concentration of the cell.

23. What is the solution? 40% Salt 10% Salt 15% Salt 10% Salt 40% Salt 15% Salt Hypotonic Hypertonic Isotonic

24. What is the cell? 40% Salt 10% Salt 15% Salt 10% Salt 40% Salt 15% Salt Hypertonic Hypotonic Isotonic

25. Remember! In osmosis, goes towards the !

26. Passive Transport: Facilitated Diffusion A B Facilitated diffusion: diffusion of specific particles through transport proteins found in the membrane • Transport Proteins are specific – they “select” only certain molecules to cross the membrane • Transports larger or charged molecules Facilitated diffusion(Channel Protein) Diffusion (Lipid Bilayer) Carrier Protein • http://bio.winona.edu/berg/Free.htm

27. Passive Transport: 2. Facilitated Diffusion Glucose molecules Cellular Transport From a- High High Concentration Cell Membrane Protein channel Low Concentration Low Transport Protein Through a 

28. Facilitated Diffusion: • Molecules will randomly move through the opening like pore, by diffusion. This requires no energy, it is a PASSIVE process. Molecules move from an area of high concentration to an area of low conc.

30. Active Transport • Active transport is when the cell membrane “imports” or “exports” substances that are needed that do not travel by diffusion. • Usually, this means obtaining substances against the concentration gradient • Substances go from areas of LOW concentration to areas of HIGH concentration

31. Active Transport

32. Sodium Potassium Pumps (Active Transport using proteins) Types of Active Transport • 1. Protein Pumps -transport proteins that require energy to do work • Example: Sodium / Potassium Pumps are important in nerve responses. Protein changes shape to move molecules: this requires energy!

33. Active Transport • Active Transport uses energy called ATP. • Active Transport = ATP • Accomplished by the proteins embedded within the cell membrane.

34. Active Transport • The lack of efficient pumps can be classified as a disease. • Sodium Deficiency can cause muscle spasms, and Liddie's Syndrome. • Potassium deficiencies can cause an irregular heart beat, epileptic seizures in infancy, and deafness. •  Examples of active transport include: • Kidney's removing sodium • Thyroid obtaining iodine • Gills removing salt from water • Plants obtaining minerals through the roots.

35. Summary

36. Cytosis: A type of Active Transport • Large amounts of some substances can be taken in and out of a cell directly by the membrane. Endocytosis Exocytosis

37. Types of Active Transport • Endocytosis: • Uses energy (ATP) • Cell membrane in-folds around food particle • Endocytosis of large particles is called phagocytosis, “cell eating” • Endocytosis of small particles is called Pinocytosis, “cell drinking” • forms food vacuole & digests food • This is how white blood cells eat bacteria!

38. Phagocytosis Your white blood cells can keep you healthy by using PHAGOCYTOSIS The LYSOSOMES digest the bacteria cell and then spit it out of the cell.

39. Types of Active Transport Endocytosis & Exocytosis animations 3. Exocytosis: • movement of material out of cytoplasm of the cell using ATP • membrane surrounding the material fuses with cell membrane (like endocytosis backwards) • how cells get rid of wastes

40. Vesicles and Vacuoles that fuse with the cell membrane may be utilized to release or transport chemicals out of the cell or to allow them to enter a cell. Exocytosis is the term applied when transport is out of the cell.