Chapter+4

**Carbon and the Molecular Diversity of Life**
The common elements - H, O, N, S (Sulfur), P (Phosphorus), C


 * Organic Chemistry** - Study of compounds containing carbon
 * Hydrocarbons** - Organic molecules consisting of only carbon and hydrogen
 * Isomer** - Compound that has the same numbers of atoms of the same elements but different structures and hence different properties.
 * Functional groups** - Chemical groups that affect molecular function by being directly involved in chemical reactions


 * Carbon atoms can form diverse molecules by bonding to four other atoms**
 * The Formation of Bonds with Carbon
 * 4 valence electrons = thus sharing its 4 electrons with other atoms in covalent bonds rather than accepting/donating electrons
 * Tetravalence
 * When a carbon atom has four single bonds to other atoms, the molecule is tetrahedral.
 * i.e. Methane (CH4)
 * A molecule may have more than one tetrahedral group of single-bonded atoms.
 * i.e. Ethane (C2H6)
 * When two carbons are joined by a double bond, all atoms attached to these carbons are in the same plane (flat)
 * i.e. Ethene (ethylene) (C2H4)
 * NOTE - CO2 is considered inorganic, even though it contains carbon (WHY?)
 * Because CO2 is a very simple molecule and lacks hydrogen
 * Molecular Diversity Arising from Carbon Skeleton Variation
 * Length
 * Branching
 * Double bonds
 * Rings
 * Types of isomers
 * Structural isomers - Different in covalent arrangements of atoms / in the location of double bonds
 * Example Pentane vs. 2-methyl butane (pg 62)
 * Geometric isomers - Same covalent partnerships, but differ in their spatial arrangements
 * //Cis// Isomer - Two Xs are on the same side (pg 62)
 * //Trans// Isomer - Two Xs are on opposite sides (pg 62)
 * Enantiomers - Differ in spatial arrangement around an asymmetric carbon, resulting in molecules that are mirror images, like left and right hand


 * A small number of chemical groups are key to the functioning of biological molecules**
 * The distinctive properties of an organic molecule depend not only on the arrangement of its carbon skeleton but also on the molecular components attached to that skeleton.
 * These groups may participate in chemical reactions or molecular shape.
 * The number and arrangement of the groups help give each molecule its unique properties.

(Missing Methyl)
 * The Chemical Groups Most Important in the Processes of Life**
 * Key seven chemical groups in biological processes are:
 * Chemical Group's Name of Compound
 * Hydroxyl - **Alcohols**
 * Carbonyl - **Ketones** (if carbonyl is within a carbon skeleton) / **Aldehydes** (if carbonyl is at the end of a carbon skeleton)
 * Carboxyl - **Carboxylic acids**
 * Amino - **Amines**
 * Sulfhydrl - **Thiols**
 * Phosphate - **Organic phosphates**
 * Methyl - **Methylated compounds**


 * ATP: An Important Source of Energy for Cellular Processes**
 * ATP = Adenosine Triphosphate (meaning Three phosphates attached to adenosine)
 * ATP => Adenosine diphosphate (by Hydrolysis - reaction with water)