Carbon and the Molecular Diversity of Life Chapter 4

The Backbone of Life All living organisms are largely made up of chemicals that are based on elements of carbon –Other common ingredients include hydrogen, oxygen, nitrogen, sulfur, and phosphorous –The diversity of life is related to carbon and its ability to bond with other elements in a variety of ways

Organic Chemistry All compounds containing carbon are said to be organic –Most also contain hydrogen Be familiar with Miller’s experiment on page 59.

Carbon and Bonding Carbon has 6 electrons which means only 4 are in the valance shell, leaving 4 “holes” to fill –Carbon generally shares its 4 carbon atoms via covalent bonds –In molecules, carbon can act as a hub where the molecule can branch off in as many as 4 directions (tetravalence).

Carbon and Molecular Diversity Carbon skeletons vary in length Skeletons may be branched or unbranched The skeleton may have double bonds, which can vary in number and location Some carbon skeletons are arranged in rings

Hydrocarbons Consists only of carbon and hydrogen –Ex: Major component of petroleum Not common alone in living organisms, but are common on regions of molecules –Ex: Fat has a hydrocarbon tail attached to a nonhydrocarbon component Tend to be hydrophobic (because nonpolar) Reactions tend to release large amounts of energy

Isomers Compounds that have the same numbers of atoms of the same elements, but different structures and properties –Structural Isomers – differ in their covalent arrangement of atoms and may fiffer in the placement of their double bonds –Geometric Isomers – have the same covalent partnerships, but they differ in their spatial arrangements –Enantiomers – isomers that are mirror images of each other Usually 1 is biologically active and the other is not Ex: Thalidomide use in pregnant women –“good” version reduced morning sickness –“bad” version caused birth defects

Functional Groups At times, a chemical group may replace one or more of the hydrogens bonded to the carbon skeleton. These groups may participate in reactions and may play a role in the function of the molecule because of shape

Functional Groups 1)Hydroxyl –Hydrophilic; increases solubility

Functional Groups 2) Carbonyl –Hydrophilic; increases solubility –Know the difference between a ketone and an aldehyde

Functional Groups 3) Carboxyl –Hydrophilic; increases solubility

Functional Groups 4) Amino –Hydrophilic; increases solubility

Functional Groups 5) Sulfhydryl –Hydrophilic; increases solubility

Functional Groups 6) Phosphate –Hydrophilic; increases solubility

Functional Groups 7) Methyl –Non-Reactive –Acts as a recognizable tag on biological molecules

ATP Adenosine Triphosphate – Organic molecule consists of an adenosine molecule attached to a string of 3 phosphate groups –A reaction with water causes the release of one of the phosphate groups also releasing energy. Molecule becomes ADP