The structure and function of a multicellular organism depends on the structural and functional characteristics of its cellsCell Theory–Cells are the basic unit of life–All living organisms are composed of cells–All cells come from pre-existing cells“Omnis cellula e cellula”~ Rudolph Virchow (but actually plagiarized…)The success of each cell as a whole depends on the integrated function of many discrete membrane bound organelles (functional compartmentalization)2*Reading assignment: Lucey et al 2009
The plasma membrane provides a selectively permeable barrier between the intracellular and extracellular environmentPhospholipid bilayer provides primary barrier functionMembrane proteins function in selective permeability, signal transduction, cell-cell interaction, anchor to ECM and cytoskeleton, etc.3Campbell NA, Reece JB. Biology. 7thed. San Francisco CA: Benjamin Cummings, 2005. p 127.
Review of pertinent basics: The hydrophobic effectA system will spontaneously move towards a state of equilibrium where energy is at a minimum and entropy is at a maximumThe aggregation of non-polar molecules in an aqueous environment is a thermodynamically favorable process driven by entropy!Spontaneous self-assembly of biomolecules•Phospholipid formation of micelles, liposomes, and bilayers are the most thermodynamically stable state depending on ration of phospholipid to water•Protein native structure is most thermodynamically favorable state for the given polypeptide chain4Lodish H et al. Molecular Cell Biology. 5thed. New York: W.H. Freeman, 2004. p 35 and 45.
Modes of Membrane Transport 5Moyes CD, and Schulte PM. Principles of Animal Physiology. San Francisco: Pearson Benjamin Cummings, 2006. p 85.