HELLS CELLS

1
introduction
2
HELLS CELLS This Thursday at 4 until ? Lab
3
Membranes define the anatomy of the cell
4
Membranes define two compartments inside and
outside
5
chemical composition
6
The history of our understanding of the cell
membrane
7
Which alcohol would penetrate a cell membrane
most rapidly?

• Glycerol CH2OH-CHOH-CH2OH
• Ethanol CH3-CH2OH
• Methanol CH3OH
• Propanol CH3-CH2-CH2OH

8
(No Transcript)
9
Cartoon of a polar lipid
Phospholipid bilayer
10
Why is a membrane like a rubber band?

• Bilayer formation and rubber band snapping are
  both driven forwatd by entropy increases.
• Bilayer formation and rubber band snapping are
  both endergonic.
• Bilayer formation and rubber band snapping are
  both exothermic.
• Bilayer formation and rubber band snapping are
  both driven by entropy decreases.

11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
Lipids in the cell membrane are distributed
asymmetrically
15
The enzymes that add carbohydrates to proteins
and lipids are found in the lumen of the Golgi.
Therefore, carbohydrates are always on which side
of a membrane?

• Outside
• Inside
• Both sides

16
membrane fluidity
17
(No Transcript)
18
(No Transcript)
19
Flippase catalyzes its reaction by lowering the
free energy (G) of

• the polar head within the hydrophobic center of
  the lipid bilayer.
• the polar heads on both sides of the membrane.
• the lipid bilayer as the polar head moves through
  it.

20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
Which membrane is least fluid?

• Membrane made from phosphatidylcholine with
  saturated 16-C fatty acids
• Same as 1, except each of the 16-C fatty acids
  has a single cis double bond.
• Same as 1, except each of the saturated fatty
  acids has only 14 carbon atoms.

25
Cholesterol
Decreases membrane fluidity at higher
temperatures Increases membrane fluidity at lower
temperatures Decreases permeability of membrane
to small polarmolecules
26
proteins
27
(No Transcript)
28
(No Transcript)
29
(No Transcript)
30
(No Transcript)
31
(No Transcript)
32
(No Transcript)
33

-
34
3.75 nm
3.75 nm 0.15 nm/ aa
25 aa
0.15 nm rise per residue
35
(No Transcript)
36
(No Transcript)
37
How many alpha-helical passes through the
membrane does this protein have?

• 0
• 3
• 6
• 7

38
Band 3 anion exchange protein Glycophorin
39
(No Transcript)
40
carbohydrates
41
N-linked carbohydrate
O-linked carbohydrates
42
(No Transcript)
43
(No Transcript)