Chapter 2 The Chemical Basis of Life Chemistry Organic Molecules Part 1 General Chemistry Organisms mostly made of C H N O o Other elements are required for life ex Na Mg P Cl Pauling units Relative Electronegativities see slides o E N 0 4 nonpolar covalent E N 5 2 polar covalent o Dipole molecule that has poles Hydrogen Bonds o H atom is attracted to the negative pole of another atom F O N o Individual H bond is weak but several together is strong Ionic Bonds o E N 2 3 3 Water o Attracted to more water adhesion other molecules cohesion o Primary solvent in organisms Thermically stable high specific heat o Adding solute lowers FP pH o pure H2O ionizes into H OH o Acids release H o Bases remove H from solution o Organisms regulate their internal pH and it even varies within different in solution components of cells see slide for exact numbers Part 2 Organic Molecules I General A Contain carbon B Can have both nonpolar polar parts 1 C H bonds are nonpolar 2 C O bonds are polar 3 O H bonds are polar C Fig 2 14 Different ways of drawing molecules D Isomers same chemical formula different structures Four Major Types of Organic Molecules Biochemistry I Proteins A Contain C H O N and usually S B Consist of 1 or more polypeptides C The building block Monomer antithesis of polymer of proteins is the amino acid 1 Amino Acid Structure picture 2 R Group Chemistry a Can be categorized 3 ways Nonpolar Polar determines AA uncharged Polar charged i This affects how the AA behaves in water and what the protein shape is The shape of the protein has a large affect on function ii Use electronegativity to determine polarity of AA side chains D Different from other 3 classes of organic molecules E Polypeptide linear chains of covalently linked AA s Fig 2 17 1 Amino group at one end is called amino terminus or N 2 Carboxyl group on other side is carboxyl terminus or C terminus terminus the molecule the next in the chain 3 Count number of R Groups O s or N s to find out how many AA s are in 4 Peptide Bonds form between the carboxyl group of one AA the amino group of R group side chain variable group is the thing that changes subsequently determines what AA it is Amino group accepts an H base Nitrogen goes from N N and the carboxyl group donates an H acid OH O Base thymine etc Phosphate group 5 4 1 O 3 2 II Nucleic Acids DNA RNA A Polymers of nucleotides B Store express transmit genetic information C Associate with proteins to form structures in the cell rRNA D Structure 1 Fig 2 18 2 Bond between phosphate group sugasr comes from dehydrating HPO4 Sugar Deoxyribose to PO4 phosphate group E Carbons in the sugar labeled Prime F One source of variability is the structure of the base Nucleotide Structure bases 1 Pyrimidines Single ring a Cytosine b Thymine DNA only c Uracil RNA only 2 Purines Double ring a Guanine b Adenine bases G Other source of variability Structure of the Sugar 1 Ex at the 2 carbon of the sugar in DNA the carbon lacks an oxygen 2 Look at the 2 carbon in the sugar to find if you re in DNA or RNA DNA deoxynucleic acid has H RNA has OH H The 5 Carbon of the sugar is not on the ring of the sugar It s on the end of the stick attached to the phosphate group 1 There will always be 5 carbons in the sugar I Strands of DNA phosphate group of 21 nucleotide covalently bonds to the 3 carbon of the sugar on the next nucleotide 1 Forms phosphodiester bond Fig 2 20 2 A strand is linear not branched 3 All sugars in a given strand have the same orientation Either 3 5 or 5 3 III Carbohydrates A Structure C H2O B Simple monosaccharides MS 1 Hexoses 6C a Ex Glucose C6H12O6 2 Pentoses 5C a Ex Ribose C5H10O5 Deoxyribose C5H10O4 3 Monosaccharide unbranched carbon chains that form rings in solution C Monosaccharides link together covalently to form polysaccharides 1 Can be digestible or indigestible ex cellulose fiber 2 Don t have to be a line of monosaccharaides can be branched 3 Can be made up of different monosaccharaides IV Lipids A General 1 Contain lots of primarily H C 2 Nonpolar 3 Insoluble in H2O a Hydrophobic B 3 types Overview 1 Fats energy storage structural support a Structural support ex behind eye 2 Steroids cholesterol hormones a Communication molecules 3 Phospholipids from cell membranes C Fats 1 Made from 3 fatty acids a glycerol a Fatty acids long C H chains with a carboxyl group at the end i Carboxyl group releases H in H2O b 2 types of fatty acids i Saturated all C s linked by single bonds solid at room temp straight ii Unsaturated 1 double bonds liquid at room temp bent chain chain D Steroids 1 4 interconnected C rings 2 Ex Cholesterol 3 Differentiate from polysaccharides no oxygen in steroids E Phospholipids 1 A charged nitrogen containing molecule phosphate group 2 fatty acids 2 Saturated Unsaturated
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