Cell Membrane

Cellular Metabolism - CH11
Organelles

Cell/Plasma Membrane

Function/Purpose:

Primary Function - Lipids

• Semipermeable membrane that surrounds and proctects the organelles of the cell
  • "skin" of the cell

Secondary Function - Proteins and Carbohydrates

• Transport - regulate cell ions
  • Pumps
  • Channels
• Receptors - Signal Transduction!
• Enzymes - Enzymes

Fundamentals:

• 1)Membrane Fluidity
• 2)Common CM Attributes
• 3)Movement Across CM

Anatomy/Structure:

• Polar head group
• Hydrophilic hydrocarbon tail
• Membrane Proteins (typically 50% - energy tranduciton 75%)
  • WHY Proteins? hydrophobic components do not conduct currents well but we have currents necessary to life (neuronal, cardiac)
    • These give other functions to the membrane

Structural Specifics:

• Favored structure for most phospholipids and glycolipids is a lipid bilayer of two lipid sheets
• Lipid bilayers form through spontaneous self assemply process
  • Rapid and spontaneous in water
    • Hydrophobic effect is a major driving force to lipid bilayers
    • Van Der Waals favor the close packing of the tails
    • Electrostatic and Hydrogen bonding with the solution (water)

Concepts:

• Types of Interactions - Covalent, Noncovalent, Hydrophobic effect, Van Der Waals
• Solubility rules
• Biomolecule - Lipids, Proteins, Carbohydrates
• The Cell

Terminology:

• Spontaneous Gibbs Free Energy
• Liposome/lipid vesicle: small aqueous compartment surrounded by a lipid bilayer
• Lateral diffusion: rapid lateral movement of membrane proteins

Applications:

• Liposome can be used to study behavior of typical cel membranes
• Liposomes concentrate in areas of increased blood circulation
  • DNA gene therapy/drugs to be injected into patients
    • Reduces the potential toxic drugs
• Membrane Proteins: speicifc proteins that mediate nearly all other membrane functions

Additional Information: