SCIE1106 Lecture Notes - Lecture 28: Glycocalyx, Phosphatidylserine, Liposome
Membrane Structure
Wednesday, 12 October 2016
12:51 pm
Membrane Structure:
• Plasma membrane - dividing cytosol/cytoplasm to the extracellular components
• Within the cell, there are a lot of membranes surrounding organelles
• Mitochondria and nuclear envelope are double membranes
• Other organelles - single membranes
Function of Plasma Membrane:
• Selectively permeable
• Receiving information
• Import and export of small molecules
• Capacity for movement and expansion
Structure of Plasma Membrane:
• Lipid bilayer
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• Made up of phospholipids and protein molecules
• 50:50 phospholipids/protein
Freeze Fracture:
• Old technique to look at morphology of bilayer
• Used because microscopic technology wasn't as advanced as it is now
• Cells put in liquid nitrogen to freeze
• Knife slices membrane to look at both layers
• Pits in cytoplasmic layer are because of proteins
Hydrophilic vs. Hydrophobic in Water:
• Hydrophilic - dipole group allowing for hydrogen bonding
• Hydrophobic - usually saturated
Phospholipids:
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• Amphipathic - contains hydrophilic and hydrophobic groups
• Blue group - different for different phospholipids
• Usually one fatty acid is saturated, and one has a cis-double bond
• 4 major phospholipids
o Phosphatidylethanolamine
o Phosphatidylserine
o Phosphatidylcholine
o Sphingomyelin
• Phospholipids spontaneously form biolayers
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