Chapter 4: Carbon and the Molecular Diversity of Life

I. Organic Chemistry  Branch of chemistry focusing on carbon compounds  Berzelius: first to distinguish between organic (from living) and inorganic (from non-living) compounds  Wohler: made urea from “inorganic” compounds  Miller: made organic compounds from early Earth-like atmosphere

II. Versatility of Carbon  Does not form ionic bonds very often  Tetravalent - makes four covalent bonds  Can make large, complex molecules  Carbon is very compatible with other elements  CO 2 is the source of all carbon in organisms

III. Changes in the Carbon Skeleton  Hydrocarbons - only hydrogen and carbon  Isomers - same molecular formula, different structures  Structural Isomers, Geometric Isomers, and Enantiomers

IV. Functional Groups  Regions of organic molecules most commonly involved in chemical reactions

A. Hydroxyl Group  -OH  Alcohol - organic compound containing an hydroxyl group (ethanol)  Polar because of electronegative oxygen

B. Carbonyl Group  -CO : oxygen atom joined to a carbon atom through a double bond  Aldehyde - carbonyl group is at the end of the carbon skeleton (propanal)  Ketone - carbonyl group anywhere else (acetone)

Formaldehyde and Acetone

C. Carboxyl Group  -COOH : oxygen atom is double-bonded to a carbon atom that is also bonded to a hydroxyl group  Carboxylic (organic) acids  Formic acid and acetic acid

D. Amino Group  -NH 2 (-NH 3 - )  Amines  Amino Acids

E. Sulfhydryl Group  -SH  Resembles a hydroxyl group. WHY?  Thiols  Found in Cysteine

F. Phosphate Group  -PO 4 2- : phosphate ion covalently attached by one of its oxygen atoms to the carbon skeleton  Nucleic acids