1 Chapter 4 Carbon and the Molecular Diversity of Life

2 Carbon Chemistry Carbon is the Backbone of Biological Molecules (macromolecules) All living organisms Are made up of chemicals based mostly on the element carbon Figure 4.1

3 Carbon Chemistry Organic chemistry is the study of carbon compounds Carbon atoms can form diverse molecules by bonding to four other atoms Carbon compounds range from simple molecules to complex ones Carbon has four valence electrons and may form single, double, triple, or quadruple bonds

4 Hydrocarbons Hydrocarbons are molecules consisting of only carbon and hydrogen Hydrocarbons Are found in many of a cell’s organic molecules (a) A fat molecule (b) Mammalian adipose cells 100 µm Fat droplets (stained red) Figure 4.6 A, B

5 Isomers Isomers are molecules with the same molecular formula but different structures and properties Three types of isomers are –Structural – variation in covalent bonding –Geometric – variation around a central double bond –Enantiomers – mirror images

6 H H HH H H H H HH H H H HH H H H H H H H H H H H H H CO 2 H CH 3 NH 2 C CO 2 H H CH 3 NH 2 XX X X C CCCC C C C C C C C C C C (a) Structural isomers (b) Geometric isomers (c) Enantiomers H Figure 4.7 A-C

7 Enantiomers Are important in the pharmaceutical industry L-Dopa (effective against Parkinson’s disease) D-Dopa (biologically inactive) Figure 4.8

CH 3 OH HO O CH 3 OH Estradiol Testosterone Female lion Male lion Figure Functional Groups Functional groups are the parts of molecules involved in chemical reactions They Are the chemically reactive groups of atoms within an organic molecule Give organic molecules distinctive chemical properties

9 Six functional groups are important in the chemistry of life –Hydroxyl –Carbonyl –Carboxyl –Amino –Sulfhydryl –Phosphate

Hydroxyl -OH Polar Water Soluable (Hydrophilic) Alcohols Ex: Ethanol 10

Carbonyl -C=O Polar Water Soluable (Hydrophilic) Aldehydes and Ketones –AldeHydes, and Ketones look like keys in locks Ketones are produced when fat is broken down instead of sugar – can show up in diabetic’s urine 11 Acetaldehyde: The product of alcohol metabolism

Carboxyl -COOH Polar Water Soluable (Hydrophilic) Acid –OH can become H+ in solution Ex: Acetic Acid in vinegar 12

Amino -NH 2 Polar Water Soluable (Hydrophilic) Weak Base – Can accept a H+ to become NH 3 Ex: Amino Acids 13

Sulfhydral -SH Polar Water Soluable (Hydrophilic) Forms disulfide bridges Stabilizes protein shapes Ex: Thiols 14

Phosphate PO 4 Polar Water Soluable (Hydrophilic) Acid Important in energy transfer Ex: ATP 15

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