1. 5.1 Mini Lecture
AP Biology

3. Which model was correct?
PDQ 1.
Singer and Nicholson

4. PDQ #2 Polar group – phosphate group  negative charge
Net negative charge

5. Add descriptions/functions
PDQ #3 Membrane Parts
Add descriptions/functions
Integral Proteins
transports molecules across membrane
B. Peripheral Proteins –
transports molecules from protein to protein
do NOT penetrate the membrane
are hydrogen bonded to membrane

6. Add descriptions/functions
PDQ #3 Membrane Parts
Add descriptions/functions
C. lipid Bilayer
Hydrophilic end of phospholipids
Polar head
Has a negative charge
Hydrophobic end of phospholipids
Nonpolar tail
Cholesterol
Maintain fluidity of membrane
See steroid structure?

7. Add descriptions/functions
PDQ #3 Membrane Parts
Add descriptions/functions
Glycolipid
Carbohydrate + lipid
Cell recognition
Glycoprotein
Carbohydrate + protein
Assist in binding of hormones
Oligosaccharides
Small polysaccharides
Cytoskeleton
Cell shape, movement of organelles

9. #4. What is meant by the phrase, membranes are asymmetric.
Proteins are embedded asymmetrically across the membrane

10. #5. What components of the cell membrane contribute to the fluid quality of the cell membrane?
Cholesterol – maintain the fluidity
Fatty acids on hydrophobic portion (nonpolar tails)

11. Cholesterol
Controls the fluidity of the cell membrane

12. Phospholipids Phospholipids may differ in: Fatty acid chain length
Degree of saturation
Kinds of polar groups present

13. PDQ 6 Two important factors in membrane fluidity:
Lipid composition—types of fatty acids can increase or decrease fluidity
Temperature—membrane fluidity decreases in colder conditions
APPLY THE CONCEPT Biological membranes have a common structure and are fluid
INTERACTIVE TUTORIAL 5.1 Lipid Bilayer: Temperature Effects on Composition

14. Proteins
Peripheral membrane proteins lack hydrophobic groups and are not embedded in the bilayer.
Integral membrane proteins are partly embedded in the phospholipid bilayer.
PDQ 7.
transmembrane protein extends through the bilayer on both sides

15. PDQ 8. Amphipathic – has hydrophilic and hydrophobic portions
permanent

16. 9. Types of amino acid side chains interface with fatty acid chains
Nonpolar
Hydrophobic
Non-charged

17. 10. Glycoprotein vs. Glycolipid
Glycoprotein – carbohydrate attached to a protein
Glycolipid – carbohydrate attached to a lipid

18. 11. Roles of carbohydrates on surface of cell membrane
Binding sites for molecules
Help hold adjacent cells together