Chapter 4 Carbon and the Diversity of Life

Chapter 4: Carbon and the Diversity of Life • Organic molecules: molecules that contain carbon Carbon: valence of 4 form 4 covalent bonds Variations in carbon skeletons contribute to the diversity of organic molecules.

Hydrocarbons: molecules containing only carbon and hydrogen -are hydrophobic and nonpolar Major component of many Lipids (fats)

Isomers • compounds with the same molecular formula but with different structures (hence different properties)

Three types of isomers [Figure 4. 6] • Structural isomers – covalent partners • Geometric isomers – rearrangement around double bond (rhodopsin) • Enantiomers – 3 -D shape /mirror image - require asymmetric carbons

Functional Groups • contribute to molecular diversity and behave consistently from one organic molecule to another

Hydroxyl Group – consists of a hydrogen atom bonded to an oxygen atom, which in turn is bonded to carbon (-OH) Contributes polarity Organic compounds with hydroxyl groups are called alcohols

Carbonyl Group – consists of a carbon atom double bonded to an oxygen (-C=O) Contributes polarity A functional group found in sugars aldehyde(“hides at end”) or ketone (“right at home, mixing in)

Carboxyl Group • consists of a carbon atom which is both doublebonded to an oxygen and single-bonded to a hydroxyl group (-COOH) Contributes polarity hydrogen reversibly dissociates as H+ (acidic properties). Compounds with this functional group are called carboxylic acids.

Amino Group – consists of a nitrogen atom bonded to two hydrogens and to the carbon skeleton (-NH 2). Contributes polarity Acts as a weak base. The unshared pair of electrons on the nitrogen can accept a proton, giving the amino group a +1 charge. Organic compounds with this functional group are called amines.

Sulfhydryl Group – consists of an atom of sulfur bonded to an atom of hydrogen (-SH). * Contributes polarity Help stabilize the structure of proteins Organic compounds with this functional group are called thiols.

Phosphate Group – (-OPO 3) Contributes polarity Organic phosphates are important in cellular energy storage and transfer (i. e. , ATP)

Methyl Group – Functional group which consists of a carbon and three hydrogen atoms (-CH 3) Nonpolar group (hydrophobic)