1. Membrane Structure and Function
Chapter 4
Membrane Structure and Function

2. Phospholipid - amphipathic molecule

3. Membrane Lipids - phospholipid & cholesterol
Membrane Proteins - integral & peripheral

4. Why don't phospholipid molecules flip laterally??
FLUID
due to lipid content
unsaturated fats = more fluidity
hydrocarbon tails wiggle; move laterally
Why don't phospholipid molecules flip laterally??
cholesterol
keeps membrane from freezing at decreased temperatures
stiffens the membrane at increased temperatures

5. MOSAIC due to protein content number and types of proteins vary
proteins in no set position

6. Carbohydrates glycocalyx protection facilitates adhesion between cells
glycolipids & glycoproteins
only occur on outside surface
glycocalyx
protection
facilitates adhesion between cells
reception of signaling molecules
cell-to-cell recognition

10. Aquaporins

12. physical process due to the random motion of particles
DIFFUSION
physical process due to the 
random motion of particles

13. OSMOSIS
water moves from an area of HIGH water 
concentration (low solute concentration) to an 
area of LOW water concentration (high solute 
concentration)

15. Tonicity - the ability of a solution to cause a cell to gain or lose water
Osmotic Pressure - measure of difference in solute concentrations; force needed to stop 
osmotic flow
Hydrostatic Pressure - pressure of the cytoplasm pushing against the plasma 
membrane

17. crenation
cytolysis
turgor pressure
plasmolysis

20. Maintaining Osmotic Balance

22. Active Transport needs ATP moves UP the concentration gradient
uses highly selective protein carriers

25. Cotransport

26. Endocytosis and Exocytosis

27. Exocytosis vesicle fuses with plasma membrane = secretion
Plants - export materials to construct cell wall
Animals - secrete hormone, neurotransmitters and digestive enzymes

28. Endocytosis take in substances by vesicle formation
viruses, food, another cell, liquid
A is a bacterium
B is a WBC

31. EXTRACELLULAR MATRIX meshwork of proteins and polysaccharides
collagen resists stretching
elastin gives resilience
fibronectin (adhesive) binds to integrin
integrin makes contact with cytoskeleton - plays role in cell signaling
proteoglycans help resist compression; play role in cell signaling

33. CELL JUNCTIONS allows coordination of cells adhesive junctions
attach adjacent cells
tight junctions
plasma membrane proteins attach to each 
other
gap junction
allows cells to communicate

34. Plasmodesmata pass through cell wall
allows water and small solutes to pass freely