Notes – Chapter #4AA Carbon And The Molecular Diversity Of Life Intro: 1. Aside from water, most biologically important molecules are carbon based. 2. Carbon enters the biosphere through the action of plants. 3. Plants use solar energy to transform atmospheric carbon dioxide into the Molecules of life, which are then taken in by plant-eating animals. I. Organic Chemistry Is The Study Of Carbon Compounds 1. Compounds containing carbon are said to be organic, and the branch of chemistry that specializes in the study of carbon compounds is called organic chemistry. 2. Differences in individuals within a species, are distinguished by variations in their organic molecules. 3. The science of organic chemistry originated in attempts to purify & improve the yield of various valued substances. 4. However, at that time , it was believed that organic compounds could only arise in living organisms. 5. Jon Berzelius made the distinction between organic compounds, ( those thought to arise only in living organisms, and inorganic compounds (those found only in the nonliving world. 6. Vitalism, the belief in a life force outside the jurisdiction of physical and chemical laws, provided the foundation for the discipline of organic chemistry. 7. Various chemists were able to synthesize organic compounds in the laboratory by combining elements under the right conditions. a) Wohler – in attempt to make the salt ammonium cyanate, he synthesized urea. b) Kolbe – synthesized the organic compound acetic acid. 8. Finally, in 1953, Stanley Miller set up a closed system to mimic conditions thought to have existed on the early Earth. From the results, Miller concluded that complex organic molecules could arise spontaneously under conditions thought to have existed on the early Earth. Miller refuted the principle of vitalism. 9. These pioneers of organic chemistry helped shift the thought from vitalism to mechanism. 10. Mechanism is the view that physical and chemical laws govern all natural Phenomena, including the process of life. II. Carbon Atoms Can Form Diverse Molecules By Bonding To Four Other Atoms A. The Formation Of Bonds With Carbon 1. Carbon with a valence of 4 can bond to various other atoms, including O, H, and N. 2. Carbon can also bond to other carbon atoms, forming the carbon skeletons of organic compounds. B. Molecular Diversity Arising From Carbon Skeleton Variation 1. The skeletons vary in a) length b) it may be straight, branched, or arranged in closed rings c) some carbon skeletons have double bonds, which vary in number & location. d) atoms of other elements can be bonded to the skeletons at available sites. C. Hydrocarbons 1. Hydrocarbons are organic molecules consisting of only carbon and hydrogen. 2. The hydrophobic compound, fat does not dissolve in water because the great majority of their bonds are relatively nonpolar carbon-to-hydrogen linkages. D. Isomers 1. Isomers are compounds that have the same number of atoms of the elements but different structures and hence different properties. 2. Three types of isomers are a) Structural isomers – structural isomers differ in covalent arrangements of their atoms. b) Cis-trans isomers – (formerly called geometric isomers), carbons have covalent bonds to the same atoms, but these atoms differ in their spatial arrangement due to the inflexibility of double bonds. c) Enantiomers – are isomers that are mirror images of each other and that differ in shape due to the presence of an asymmetric carbon (one that is attached to four different atoms). III. A Few Chemical Groups Are Key To The Functioning Of Biological Molecules 1. Chemical groups attached to the carbon skeletons of organic molecules participate in chemical reactions. These functional groups contribute to function by affecting molecular shape. 2. The seven chemical groups most important in biological processes are a) b) c) d) e) f) g) hydroxyl carbonyl carboxyl amino sulfhydryl phosphate methyl 3. See pages 64 & 65 for the structure, name of compound, example & functional properties. Know the bold faced information. A. ATP: An Important Source of Energy for Cellular Processes 1. ATP is a nucleotide consisting of adenosine, attached to three phosphate groups. (A nucleotide consist of - a sugar, a base & a phosphate) 2. ATP can react with water forming inorganic phosphate and ADP (adenosine diphosphate) . This reaction releases energy that can be used by the cell.