Membrane Structure & Function BSCI 420,421Lecture 14Oct 2002 Ghandi’s eyes looked out to sea....
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Transcript of Membrane Structure & Function BSCI 420,421Lecture 14Oct 2002 Ghandi’s eyes looked out to sea....
Membrane Structure & Function
BSCI 420,421 Lecture 14 Oct 2002
Ghandi’s eyes looked out to sea. “When I was a boy,I used to sing a song in the temple: A true discipleknows another’s woes as his own. He bows to all anddespises none.”
1. Membrane functions2. Membrane structure3. Membrane fluidity
Membranes serve a wide variety of functions
1. Barriers to separate cells from environment(plasma membrane)and one compartment from another (organelle membranes)
2. Transport – Passive, active, and vesicular transport
3. Sites for enzyme systems, e.g.a) ATP synthaseb) Cytochrome p450s
4. Conduct electrical signals
5. Recognize and respond to molecules or surfacesa) Signal mol. Receptorsb) Immune response to antigens
P-choline = red glycolipids = blueP-serine = greenP-ethanolamine = yellowSphingomyelin = brown
Asymmetry of membrane lipids
Basis of lipid asymmetry:
Synthesis of membrane lipids occurs on the ER.After they are delivered to the PM, a flippaseenzyme selectively flips PS & PE to the cytosolicleaflet. (fig 12-59).