This document provides an overview of a course on advanced cell biology. It focuses on the topic of membranes, including their structure and key components. The main points are: - Biological membranes act as barriers that compartmentalize the cell and contain lipids, integral proteins, and peripheral proteins. - The fluid mosaic model describes membranes as a fluid bilayer of lipids with integral proteins embedded. Key lipids include phospholipids and sphingolipids. Cholesterol provides rigidity. - Integral membrane proteins span the membrane and include transmembrane alpha helices. Their structure can be predicted using hydropathy plots. - Membranes establish gradients using pumps, carriers, and channels. Pumps actively transport ions using ATP.

1. Advanced Cell Biology
2014 1nd Semester
Department of Animal Science
Chungbuk National University
4nd Lecture

2. 1st week : Introduction
3rd week :Research Strategies For Cell Biology
5nd week : Nucleus, Transcription and Splicing
7nd week : Membrane and Channel
9nd week : Membrane Trafficking
11nd week : Cell Signaling
13nd week : Cytoskeleton
15nd week : Cell Cycle

3. Membrane
- Barrier between each cell and its environment
- Partition of the cytoplasm into compartments
* Nucleus
* organelles
- All biological membranes have much in common
• Fluid bilayer of lipid molecules
• Integral membrane proteins
• Pheripheral membrane proteins

4. Development of Ideas about Membrane Structure

6. “ Fluid Mosaic Model” of biological Membrane

8. Lipids : Framework of biological membrane
Hydrophilic (Water lovers )
Hydrophobic (Water haters)
Phosphoglycerides

9. • Main lipid constitutes of membranes
• Glycerol + two fatty acids + phosphoric acids +
alchohol
• Depend on alcohols esterified to the phosphates
- Phosphatidic acid [PA]
- Phosphatidylglycerol [PG]
- Phosphatidiylethanolamine [PE]
- Phosphatidylcholine [PC]
- Phosphatidylserine [PS]
- Phophatidylinositol [PI]

10. Sphingolipid : N-containing charge head

11. Cholresterol is the essential component of biological membrane
Cholresterol give ‘rigidity’ in membrane, therefore help to maintain integrity

13. Lipid rafts
Sphingolipids and cholestrol form small islands (50nm)
Involved in signalings

14. Integral Membrane Proteins

15. Transmembrane segment
- Mostly alpha-Helix
- Hydrophobics

16. Hydrophaty Plots
Plot based on the hydrophobility of amino acids in a protein

17. C-terminal isoprenoid
N-terminal myristoyl tail

18. Membrane Potential (Ion-gradient as energy)

19. Pump : enzymes that utilize energy from ATP or light or other sources to movie ions and
other solutes across membranes
- Formation of gradients expense of chemical energy
- Convert chemical energy to electric energy
Carrier : enzyme-like proteins provide passive pathway for solute to move across membranes
- From higher concentration and lower concentration
- Carriers uses ion gradient as a source of energy
Channel : ion-specific pores which can open and close transiently
- Channel open : ion passes quickly across membrane
- Channel close : stop
- Movement of ions through channel is basis of control of electric potential across mebrane

21. Light-driven Proton Pump : Bacteriorodopsin
Convert Light energy as chemical energy (Formation of proton gradients)

22. Mitocondrial F1 ATPase (ATP Synthase)

25. P-Type Cation Pumps : Ca2+-ATPase (SERCA1)
Ca2+ acts as important second messenger in cells
Therefore, Ca2+ concentrations should be
Pumps Ca2+ out of cytoplasm into the endoplasmic reticulum

30. Carrier : enzyme-like proteins provide passive pathway for solute to move
across membranes
- From higher concentration and lower concentration
- Carriers uses ion gradient as a source of energy

32. - Uniproters
GLUT carrier for glucose
- Antiporters
Driving ion moves in one direction, then drive substrate in the others
- Symporters
ion and substrates goes to the same directions

33. Channels
Channel : integral membrane proteins with transmembrane pores that allow particular
ions or small molecules

36. Selectivity filter of Ion Channel
Potassium (K+) channel should allow pass-through of Potassium, but Sodium

43. Voltage-gated K+ Channel
- voltage-gated K+ and Na+ channels produce action potentials in excitable cells

45. Nature 2013EM reconstitution of TRPV1

46. Ion Channel Gated by Extracellular Ligands
Glutamate Receptor

51. Aquaporin (Water Channel)

53. Xenopus oocyte injected by Aquaporin cRNA

54. Cooperation of Channel, Pump and Carrier in Cell
1. Chemical Energy from ATP was converted as concentration gradients of C+
2. Carrier uses electrochemical gradient of C+ to drive transport C+ and S

55. Epithelial Transport