Chapter 6 Lecture Outline

Chapter 6 Lecture Outline - Biology 100 Vandan Desai...

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Biology 100 Vandan Desai P a g e | 1 Chapter 6: Lipids, Membranes, and the First Cells (Lecture Outline) -------------------------------------------------------------------------------------------------------------------------- The cell membrane , or plasma membrane , is a layer 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 Allows internal environment to have chemical composition different from that of the external environment o Chemical reactions necessary for life could occur more efficiently in an enclosed area – reactants could collide more frequently o Membrane could serve as a selective barrier – keep damage away and required entry I. Lipids – (Isoprene and fatty acids are key building blocks of the lipids found in organisms) A. Carbon-containing compounds that are found in organisms and are largely nonpolar and hydrophobic (do not readily dissolve in water) B. Lipids do dissolve in liquids consisting of nonpolar organic compounds C. Molecules that contain only carbon and hydrogen, such as isoprene , are known as hydrocarbons i. Electrons are shared equally in carbon-hydrogen bonds, thus they are nonpolar ii. This property makes them hydrophobic D. Lipids do not dissolve in water b/c they have significant hydrocarbon component E. Fatty acid: consists of hydrocarbon chain bonded to a carboxyl (COOH) functional group F. Three Types of Lipids Found in Cells i. Lipids defined by physical property (solubility ) instead of chemical structure ii. As a result, structure of lipids varies widely steroids , phospholipids , & fats iii. Steroids a. Distinguished by the 4-ring structure constructed from chains of isoprene subunits b. Have different functional groups / side groups attached to those rings c. Cholesterol – has hydrocarbon “tail” formed of isoprene subunits
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Biology 100 Vandan Desai P a g e | 2 Used as the starting point for the synthesis of the mammalian hormones estrogen, progesterone, and testosterone iv. Phospholipids a. Consists of a 3-carbon molecule called glycerol that is linked o a phosphate group (PO 4 2- ) and to either two chains of isoprene or two fatty acids Isoprene “tail” = found in domain Archaea Fatty acid “tail” = found in domains Bacteria and Eukarya b. Phosphate group sometimes bonded to another small organic molecule, such as the amino acid serine v. Fats or Triglycerides a. Composed of three fatty acids that are linked to a single glycerol
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This note was uploaded on 03/08/2010 for the course BIOL 100 taught by Professor Staff during the Fall '07 term at UMBC.

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Chapter 6 Lecture Outline - Biology 100 Vandan Desai...

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