Plasma Membrane

1. Plasma Membrane

2. Plasma Membrane (AKA Cell Membrane) • What is the plasma membrane? • What does it do? • What is its composition?

4. Plasma membrane = the flexible boundary between the cell and its environment • Allows: • Things in  the cell • Things out  of the cell • Maintains BALANCE in the cell

5. What is maintaining balance in the cell called? • Homeostasis!

6. How does the plasma membrane maintain homeostasis? • Plasma membranes are selectively permeable • Selective permeability = process in which a membrane allows some molecules to pass while keeping others in/out.

7. Plasma membranes are regulators…

8. How is a screened window similar to a cell membrane?

9. Plasma Membrane Structure

10. Structure is the KEY! • The specific structure of the plasma membrane allows it to be selectively permeable

11. Plasma Membrane Structures: • Thin layer of phosopholipds, proteins, and cholesterol • Phospholipid= kind of lipid found in the cell membrane • Glycerol, 2 fatty acids, and phosphate (PO4) • Phospholipids have 2 parts

13. Each part has a different property in water! 1. Phosphate Head • Hydrophilic • Can dissolve in water 2. Lipid tails (x2) • Hydrophobic • Cannot dissolve in water

15. What does the polarity mean about the passage of water in/out of the cell? • Water CAN pass through the polar part, but CANNOT pass through the nonpolar part. • This allows the cell to prevent water loss and prevent “drowning”

16. Cell membranes consist of 2 phospholipid layers called a bilayer (think bicycle has 2 wheels)

17. Plasma Membrane • Made of: phospholipidbilayer • Phosphate head  hydrophilic • Lipid tail  hydrophobic • Carrier proteins • Cholesterol (good kind) • Called the fluid mosaic model • Moves fluidly • Mosaic of proteins scattered in membrane • http://www.youtube.com/watch?v=Qqsf_UJcfBc&feature=related

18. Cell Transport

19. Cell Transport • Diffusion = movement across a plasma membrane from HI to LO concentration • Osmosis = diffusion of water across a plasma membrane from HI to LO concentraion

20. Solution • Solution = homogeneous mixture of 2 or more substances • Made up of: • Solute = part that gets dissolved • Solvent = part that does the dissolving • Water is the UNIVERSAL SOLVENT

21. Types of Cell Transport • Water can move freely through the plasma memebrane, but can Solute??? • NO! • Water will move to reach equilibrium since the solute cannot • Which way will the water move? • Depends on the TYPE OF SOLUTION the cell is in

22. Types of Solution • Hypertonic • Solute concentration is higher in solution than cell • Water moves OUT • Cell shrinks • Hypotonic • Solute concentration is lower in solution than cell • Water moves IN • Cell Swells • Isotonic • Solute concentration is equal in solution and in cell • Water moves IN and OUT • Cell stays the same

23. Hypertonic Solution Hypotonic Solution

25. Cell Transport • Active transport = movement of substances across membrane; requires ATP • Passive transport = movement of substances across membrane; does NOT require ATP

26. Active Transport • Goes against concentration gradient • Exocytosis = move particles OUT of cell • Endocytosis = move particels IN cell • 2 kinds of endocytosis: • Pinocytosis = movement of liquid IN cell • Phagocytosis = movement of solids IN cell • http://www.youtube.com/watch?v=4gLtk8Yc1Zc&NR=1

27. Exocytosis

28. Endocytosis

31. Passive Transport • Goes with concentration gradient • Osmosis = movement of water across a membrane with concentration gradient • Facilitated Transport = movement of substances across a membrane with concentration gradient with the help of a carrier protein • http://www.youtube.com/watch?v=s0p1ztrbXPY&feature=related

32. Facilitated Transport

33. Turgor Pressure and Plasmolysis • http://www.youtube.com/watch?v=GOxouJUtEhE&feature=related