Membranes, Channels, and Transport

1
Membranes, Channels, and Transport

• John J. McGlone, PhD
• Professor
• Texas Tech University

2
Cell Membrane A semi-permeable barrier
Hydrophilic
Hydrophobic
Hydrophilic
3
(No Transcript)
4
Ion Channels and/or Voltage sensitive ion channels
Lipid bilayer
Integral Protein
5
Coated Vesicles form during receptor-mediated
endocytosis
6
(No Transcript)
7
(No Transcript)
8
Modes of Transport

• Passive transport
• Channels or pores
• Facilitated transport
• Assisted by membrane-floating proteins
• Active transport pumps carriers
• ATP is required
• Enzymes and reactions may be required

9
Pumps are used to push molecules up their
Electrical or Concentration gradient
Then.You have concentration differences across
the semi-permeable membrane
10
Osmosis
11
Non-selective membrane
Semi-permeable membrane
12
Blood or physiologic saline
Water
Concentrated salt solution
13
Normal cell inside and outside ion concentrations
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
Summary/Key points

• Membranes are semi-permeable
• Non-diffusible ions (proteins) set up osmotic
  pressure
• Pumps push against gradients
• Ionic differences across membranes cause resting
  membrane potential (voltage difference across
  membranes)