Textbook Notes (362,815)
Canada (158,059)
Biology (652)
BIOLOGY 1A03 (168)
Xudong Zhu (12)
Chapter 6

Textbook and Class Notes Collaborated - Week 2 - Unit 1 - Chapter 6 Bio 1A03

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McMaster University
Xudong Zhu

Bio 1A03 Unit One The Molecules of Life Chapter 6 Lipids Membrane and the First Cell CellPlasma MembraneLayer of molecules that surrounds the cell separating it from the external environment and selectively regulating the passage of molecules and ions into or out of the cell o Evolution of plasma membrane important because it separates life from nonlife o Chemical reactions necessary for life can occur more efficiently in an enclosed area because reactants can collide more frequently o Membrane can serve as a selective barrier keep destructive compounds out bring beneficial compounds inLipids are nonpolardo not dissolve readily in water but dissolve in nonpolar solvents o Contain many hydrocarbons o Hydrocarbonselectrons are equally shared in carbonhydrogen bonds and are therefore nonpolar hydrophobicFatty Acid o Hydrocarbon chain bonded to a carboxyl COOH functional groupLipids are defined by their solubility not their chemical structureMajor Classes and Functions of Lipids o Phospholipids glycolipids and some steroids cholesterolmembrane structure and function o Other steroidshormones and regulators o Triglyceridesfood storage o Waxesbee hives and plant leaf surfaces for the protection against HO loss 2 Fats triacylglycerols triglycerides o Consist of glycerol and 3 fatty acids linked by ester linkages o Form when a dehydration reaction occurs between hydroxyl group of glycerol and the carboxyl group of a fatty acid o Not polymers fatty acids are not monomers fatty acids are not linked together to form a macromolecule o Figure 63 page 101 FatsSteroids o Distinguished by a fourring structure o Various steroids differ by the functional group attached to fourring structure o CholesterolDistinguished by a hydrocarbon tail formed of isoprotein subunitsImportant component of plasma membranes in many organismsMammalsused as the starting point for the synthesis of several of the signaling molecules called hormones Estrogen progesterone testosteronehormones derived from cholesterol responsible for regulating sexual development and activity in human brainsCholesterol circulates in blood mainly in particles LDLsNormal liver cells remove excess cholesterol from blood receptormediated endocytes o Figure 64a page 102 SteroidsPhospholipids 2o Consist of a glycerol that is linked to a phosphate group PO and to either two chains of isoprotein or 4two fatty acids o Phosphate group can be bonded to another small organic molecule eg attached to choline o Phospholipids with isoprotein tails Archaebacteria kingdom o Phospholipids composed of fatty acids Bacteria and Eukaryote kingdoms o Figure 64b page 102 PhospholipidsLipids o Store chemical energy o Serve as signals between cells o Act as pigments that capture or respond to sunlight
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