David L. Nelson and Michael M. Cox
Lehninger Principles of
Biochemistry
Fourth Edition
Chapter 11:
Biological Membranes and Transport
Copyright © 2004 by W. H. Freeman & Company
1
Chapter Outline
• The composition and architecture of
membranes
• Membrane dynamics
• Solute transport across membranes
2
The composition and architecture of
membranes
• Proteins
• Polar lipids
• Carbohydrates (glycoproteins, glycolipids)
3
Different types of membrane have
different protein/lipid proportions
4
Membrane lipids varies for different
organelles from the same cell
5
6
7
Types of integral
proteins
8
9
10
Fluidity of
biological
membranes
• Sat’d FA
• Unsat’d FA
• Cholesterol
• Temperature
Decide the
membrane fluidity.
11
12
13
FRAP (flourescence
recovery after
photobleaching)
14
15
16
17
18
Type of transporter
• Carrier (carrier, pump) : binding site binds
to ligand; can go against concentration
gradient
• Channel : must from high  low, gate is
present
19
Type of transport system
• Simple diffusion
• Facilitated diffusion
• Active transport
– Primary: need pump, energy from ATP or light
– Secondary: need carrier, energy from ion
gradient
• Ion channel: from high  low
20
Need protein carrier?
NO
YES
Simple diffusion
Saturable with substrate?
NO
Ion channels
Produces concentration gradient?
NO
Facilitated transport
ATP, light, substrate oxidation
Primary active transport
YES
YES
Energy source?
Ion gradient
Secondary active transport
21
22
23
24
GLUT1
25
26
27
28
29
30
31
32
P-type ATPase
• Na+-K+ ATPase
• Ca2+ ATPase
Maintaining the
differences in the
ionic composition of
the cytosol and the
extracellular
medium
33
34
ABC transports
35
36
Aquaporins
37
38
39
40
41
42
43
44