Chapter 4~ Carbon & The Molecular Diversity of Life

Organic chemistry

Biological thought:

Vitalism (life force outside physical & chemical laws) Berzelius

Mechanism (all natural phenomena are governed by physical & chemical laws) Miller

Carbon tetravalence

          tetrahedron shape determines function

Hydrocarbons

Only carbon & hydrogen (petroleum; lipid ‘tails’)

Covalent bonding; nonpolar

High energy storage

Isomers

         (same molecular formula, but different structure & properties)

structural~ differing covalent bonding arrangement

geometric~ differing spatial arrangement

enantiomers~ mirror images, impt to pharmacological industry (thalidomide)

Functional Groups, I

Attachments that replace one or more of the hydrogens bonded to the carbon skeleton of the hydrocarbon

Each has a unique property from one organic to another

Hydroxyl Group

H bonded to O;

alcohols;

polar (oxygen);

solubility in water

Carbonyl Group

C double bond to O;

At end of carbon chain: aldehyde Otherwise: ketone

Functional Groups, II

Carboxyl Group -COOH

      O double bonded to C to hydroxyl;

       carboxylic acids;

       covalent bond between O and H; polar;

       dissociation, H ion (H+)

Amino Group N to 2 H atoms; -NH2

      amines; acts as a base (+1)

Sulfhydral Group -SH

      sulfur bonded to H; thiols

      also found in many amino acids and form sulfide bridges

Phosphate Group

      phosphate ion; covalently attached by 1 of its O to the C skeleton;

         important for nucleic acids (RNA and DNA) and for ATP

Polymers

Covalent monomers

Condensation reaction (dehydration reaction): One monomer provides a hydroxyl group while the other provides a hydrogen to form a water molecule

monomer + monomer + monomer . . . . . + monomer --> polymer

Hydrolysis: bonds between monomers are broken by adding water (digestion)

polymer --> monomer + monomer + monomer . . .