Chapter 4 Notes Carbon and the Molecular Diversity of Life

Concept 4.1 Compounds containing carbon are said to be organic compounds. Carbon atoms are very versatile. - have 4 valence electrons. It will share electrons in 4 covalent bonds (tetravalence)

Concept 4.2 Variation in carbon skeletons contribute to the diversity of organic molecules. - long chains form carbon skeletons - often bonded to several hydrogen atoms forming a hydrocarbon.

Concept 4.2

Isomers: compounds that have the same molecular formula, but different structures (with different properties). - structural: differ in the covalent arrangements of atoms. - geometric: same covalent properties, but differ in spatial arrangements. - enantiomers: mirror images

Concept 4.2

Concept 4.3 Functional groups: components of molecules that are often involved in chemical reactions. - ex. difference between testosterone and estrogen.

Concept 4.3 Estradiol Testosterone

Concept functional groups are commonly found. - hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, and phosphate. - all are hydrophilic and increase the solubility of organic compounds in water.

Hydroxyl group (-OH) names usually end with suffix –ol ex. ethanol organic compounds w/ OH are alcohols note: do not confuse w/ OH - Concept 4.3

Carbonyl group (-C=O) -carbon double bonded to an oxygen atom. - if at the end of the carbon skeleton will be an aldehyde (ex. propanol) - if in the middle of a carbon skeleton will be a ketone (ex. acetone)

Concept 4.3 Carboxyl group (-COOH) - oxygen is double bonded to a carbon that is also bonded to a hydroxyl group - compounds are called carboxylic acids (ex. acetic acid) - has acidic properties w/ the loss of H + ions

Concept 4.3 STRUCTURE EXAMPLE NAME OF COMPOUND FUNCTIONAL PROPERTIES Carboxyl Acetic acid, which gives vinegar its sour taste Carboxylic acids, or organic acids Has acidic properties because the covalent bond between oxygen and hydrogen is so polar; for example, Found in cells in the ionized form with a charge of 1– and called a carboxylate ion (here, specifically, the acetate ion). Acetic acidAcetate ion

Concept 4.3 Amino group (-NH 2 ) - a nitrogen atom is bonded to two hydrogen atoms and a carbon skeleton - compounds are called amines - compounds that have both amino and carboxyl groups are called amino acids - ex. Glycine - amino group can act as a base (NH 3 + )

Concept 4.3 STRUCTURE EXAMPLE NAME OF COMPOUND FUNCTIONAL PROPERTIES Amino Because it also has a carboxyl group, glycine is both an amine and a carboxylic acid; compounds with both groups are called amino acids. Amines Acts as a base; can pick up an H + from the surrounding solution (water, in living organisms). Ionized, with a charge of 1+, under cellular conditions. (ionized)(nonionized) Glycine

Concept 4.3 Sulfhydryl group (-SH) - Sulfur is bonded to a hydrogen and a carbon skeleton - compounds with –SH are called thiols - help stabilize the structure of proteins

Concept 4.3 Phosphate group (-OPO 3 2- ) - formed by dissociation of phosphoric acid (H 3 PO 4 ) - used in the transfer of energy between organic molecules.

Concept 4.3 STRUCTURE EXAMPLE NAME OF COMPOUND FUNCTIONAL PROPERTIES Phosphate In addition to taking part in many important chemical reactions in cells, glycerol phosphate provides the backbone for phospholipids, the most prevalent molecules in cell membranes. Glycerol phosphate Organic phosphates Contributes negative charge to the molecule of which it is a part (2– when at the end of a molecule; 1– when located internally in a chain of phosphates). Has the potential to react with water, releasing energy.