BIOL 200 (Section 921)
Lecture # 6/7
June 22/23, 2009
UNIT 5: MEMBRANES
, pp 70-74 (to review carbohydrate and lipid chemistry);
, pp 365
pp. 389-410 (essential) 411-421 (optional), and related questions [11-9a,b,c,d,e,f,
11-10 to 11-14, 11-17, 11-18; 12-9abce; 12-11; 12-12; 12.13; 12-15; 12-18]
, pp 56-59 (to review carbohydrate and lipid chemistry);
, pp 347
pp. 371-394 (essential) 395-403 (optional), and related questions [11-9a,b,c,d,e,f,
11-10 to 11-13, 11-15, 11-18, 11-19; 12-9abce; 12-10; 12-11; 12-12; 12-14; 12-17]
I. MEMBRANES: LIPIDS, LIPID BILAYERS
Explain the condensation reactions that occur to assemble lipids and to form glycolipids
Explain the connection between the fluid mosaic model and the evidence supporting it.
Recognize that models of membranes have to be revised constantly to account for new
Understand the properties and general synthesis of phospholipids, glycolipids,
cholesterol, and various glycosides in membrane structure
Understand the properties of integral and peripheral proteins in membrane structure
Classes of Membrane Lipids:
1. Phospholipids: the most abundant type of membrane lipid. Made of hydrophobic long chain
fatty acid tail and hydrophilic "head". Fig. 11-6.
2. Sterols-remember that these multiring structures are formed from "isoprene" subunits and have
amphipathic properties due to the OH group (see Fig. 11-7)
3. Sphingolipids- (Fig. 11-7) important in PMs , especially in the nervous system.
based on the molecule sphingosine, which is derived from serine instead of glycerol.
More complex than phospholipids.
sphingosine + 1 fatty acid=ceramide
How are lipids and proteins organized within the membranes?
Available data support the
“Fluid Mosaic Model”
), proposed by
Singer and Nicolson in 1972. This model depicts a fluid lipid bilayer with proteins embedded in
the bilayer like icebergs in an ocean.
Key Features of Fluid Mosaic Model:
Membrane lipids are
arranged in a bilayer