1. Chapter 7: Membrane Structure and Function
AP Biology
Chapter 7: Membrane Structure and Function

2. Fluid Mosaic Model:
States that membranes are composed of a lipid bilayer containing various proteins and glycoproteins some of which are mobile while others are stationary

3. Fluid Mosaic Model: Fluid?
molecules are continuously removed and replaced with newly made molecules
Can stretch
Can reseal itself

4. Fluid Mosaic Model:
Mosaic?
proteins embedded in or attached to a phospholipid bilayer

5. Fluid Mosaic Model: Composed of? 1. Lipids 2. Proteins
3. Carbohydrates (glycoproteins, glycolipids)

6. Fluid Mosaic Model: Lipids?? Phospholipids more specifically
Composed of:
Compounds with nitrogen
Phosphate group
Glycerol
Saturated and unsaturated fatty acid chains

8. Fluid Mosaic Model:
Amphiphathic molecule:

10. Fluid Mosaic Model:

11. Fluidity of Membranes:
membranes are not static
hydrophobic and hydrophilic interactions
proteins and lipids can drift, laterally in the membrane
temperature does play a role on membrane fluidity, permeability, enzyme activity
cholesterol
fluidity and function

12. Roles of Membrane
1.Containment and Separation
2. Material Exchange
3. Information Detection
4. Identification
5. Attachment reinforcement
6. Movement and Metabolism

13. Membrane Proteins and their Functions:
Proteins determine most of the membranes specific functions
Bound to cytoskeleton on cytoplasmic side and ECM on extracellular side

14. Membrane Proteins and their Functions:
Two major types of membrane proteins:
Integral
peripheral

15. Integral Proteins: penetrate the hydrophobic core of the lipid bilayer
consists of one or more stretches of nonpolar amino acids
hydrophilic parts are exposed on either end of the bilayer

17. Peripheral Proteins: not embedded in the membrane
loosely bound to the surface of the membrane
often bound to exposed parts of integral proteins

19. Functions of Membrane Proteins:
1. Transport
2. Enzyme activity
3. Cell to cell recognitions
4. Signal transduction
5. Intercellular joining
6. Attachment (cytoskeleton and ECM)

21. The Permeability of the lipid bilayer:
Hydrophobic molecules(hydrocarbons), CO2, O2
Dissolve in the membrane and pass with ease
polar, hydrophilic molecules such as ions
Have trouble passing through the membrane because of the hydrophobic core
Glucose, water(polar molecules)
Pass slowly through the membrane

22. The Permeability of the lipid bilayer:
Transport Proteins
Enhance the permeability of membrane
Substance specific
Span the width of the membrane
Two types:
Channel proteins
Carrier proteins

23. The Permeability of the lipid bilayer:
channel proteins:
having a hydrophilic channel
certain molecules and ions use to pass through the membrane
carrier proteins:
transmit molecules through the membrane by changing shape

24. Passive Transport: Diffusion Osmosis:
the tendency for molecules of a substance to spread out evenly into the available space
Osmosis:
diffusion of water across a semi-permeable membrane

25. Facilitated Diffusion
Passive Transport:
Facilitated Diffusion
passive diffusion of polar molecules and ions with the help of transport proteins
gated channels: need a stimulus to open((electrical or chemical stimulus)

26. Energy driven transport:
Active Transport:
using energy to move a substance against a concentration gradient
uses carrier proteins
energy is supplied by ATP
See sodium/ potassium pump

27. http://highered. mcgraw- hill
hill.com/sites/ /student_view0/cha pter2/animation__how_the_sodium_potassiu m_pump_works.html

28. Bulk Transport
Passing through membrane by molecules too large to fit through proteins.
Relies on ability of membrane to change shape and create vesicles and reseal itself

29. Take large molecules in
Endocytosis
Take large molecules in
Cell membrane pinches in and surrounds molecule in membrane

30. “Cell eating”: engulfing entire cell; done by some white blood cells
Phagocytosis
“Cell eating”: engulfing entire cell; done by some white blood cells

33. Receptor-mediated Endocytosis
Allows smaller molecules to enter
Molecules bind to specific receptor proteins
Egg cells take in yolk protein by this method

34. “Cell drinking”; cells take in fluid and the solutes it contains
Pinocytosis
“Cell drinking”; cells take in fluid and the solutes it contains

35. Expelling large molecules; reverse of endocytosis
Exocytosis
Expelling large molecules; reverse of endocytosis

38. For the transport type you choose,
Cells transport substances across their membranes. Choose ONE of the following four types of cellular transport.
Osmosis
Active Transport
Facilitated Diffusion
Endocytosis/exocytosis
For the transport type you choose,
Describe the transport process and explain how the organization of cell membranes functions in the movement of specific molecules across membranes

39. Essay Question:
Osmosis- discuss the result of varying stages of tonicity on an animal cells RBC vs. plant cell.
Explain the flow of water in a hypertonic environment vs. hypotonic environment
Include in your explanation solute concentration and water potential
The affect of these environments on RBC and plant cells.