CH 3 - Ch3-The Chemical Building Blocks of Life Bio1610...

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1 Ch3-The Chemical Building Blocks of Life. Bio1610 Carbon —The Backbone of Biological Molecules All living organisms are made up of chemicals based mostly on the element carbon Carbon atoms are the most versatile building blocks of molecules Atomic number 6 # electrons = 6 Carbon has little tendency to form ionic bonds by losing or gaining 4 electrons. carbon usually completes its valence shell by sharing electrons with other atoms in four covalent bonds Æ tetravalence Æ makes large, complex molecules Hydrocarbons : organic molecules that consist of only carbon and hydrogen atoms. Hydrocarbons are the major component of petroleum. Petroleum is a fossil fuel because it consists of the partially decomposed remains of organisms that lived millions of years ago. Functional groups Carbon may be bonded to functional groups with specific properties. Functional groups tend 4 to act as units during chemical reactions Æ confer specific chemical properties to the molecules. -COOH Functional groups -NH2 -SH 5 If added to a water soluble molecule, the methyl groups will decrease the solubility of that molecule. -PO 4 -CH 3 Isomers are compounds that have the same molecular formula but different structures and therefore different chemical properties. For example, butane and isobutane have the same molecular formula C 4 H 10 , but butane has a straight skeleton and isobutane has a branched skeleton. The two butanes are structural isomers , molecules with the same molecular formula but differ in the covalent arrangement of atoms.
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2 Stereoisomers are compounds with the same carbon skeleton but differ in how the groups attached to the skeleton are arranged Æ differ in their spatial arrangement around a carbon- carbon double bond . The double bond does not allow atoms to rotate freely around the bond axis. Enantiomers are molecules that are mirror images of each other. A molecule that has mirror-image versions is called Chiral . Enantiomers are possible if there are four different atoms or groups of atoms bonded to a carbon They are like left- handed and right- hd d i handed versions Usually one is biologically active, the other inactive subtle structural differences in two enantiomers have important functional significance because of emergent properties from the specific arrangements of atoms . One enantiomer of the drug thalidomide reduced morning sickness, its desired effect, but the other caused severe birth defects. The L-Dopa isomer is an effective treatment of Parkinson’s disease, but the D-Dopa isomer is inactive. L: Levorotatory (rotate polarized light to the left) D: Dextrorotatory: rotate light to the right. The FOUR basic groups of biological molecules are: In each case, they are built from simple carbon-based “building blocks”.
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This note was uploaded on 09/28/2010 for the course BIO 1620 taught by Professor Bybee during the Fall '06 term at Utah Valley University.

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CH 3 - Ch3-The Chemical Building Blocks of Life Bio1610...

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