Carbon and the Molecular Diversity of Life Chapter 4

Organic molecule - molecule contains carbon. Living things also composed of other elements (i.e. hydrogen (H), oxygen (O), nitrogen (N), sulfur (S), and phosphorus (P))

Carbon - 6 electrons (2 in first shell, 4 in second) Carbon is therefore likely to form covalent bonds.

Carbon chains form skeletons of most organic molecules. Hydrocarbons - organic molecules that consist of only carbon and hydrogen atoms. Fats - long hydrocarbon tails attached to a non-hydrocarbon component.

Examples of carbon bonding

Long hydrocarbon chains

Isomers - compounds that have same molecular formula but different structures and chemical properties. 1 Structural isomers - molecules that have same molecular formula but are different in structure.

Butane – both are C 4 H 10 but are set up differently

2 Geometric isomers - same covalent bonds but differ in how electrons are placed. Usually double-bonded molecules. Because of double bond, molecules cannot rotate around double bond.

Position of “X” prevents the rotation of the molecule.

3 Enantiomers - mirror images of each other (like left and right-hand images) There has to be 4 different atoms attached to carbon for there to be an enantiomer.

Diagram on left cannot be rotated to match diagram on right

Functional groups Functional groups - groups of organic molecules most often used in chemical reactions. Arrangement of functional groups give molecules their uniqueness.

Note difference between male and female hormone

6 functional groups. 1 Hydroxyl group (-OH) – Polar covalent bonds - increase solubility of molecule. Contains functional group - alcohol.

2 Carbonyl group (CO) – Oxygen atom joined to carbon skeleton by double bond. If it is attached to end of molecule - aldelhyde. If not it is a ketone.

3 Carboxylic group (COOH) – Acts as an acid. Known as carboxylic acids.

4 Amino group (NH 2 ) - Acts as base. Known as amines.

5 Sulfhydryl group (SH) – Help stabilize structure of proteins. Known as thiols.

6).Phosphate group (PO 4 ) – One function of this group to transfer energy between organic molecules.