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Chapter 4 Carbon and the Molecular Diversity of Life. Ch 4 Carbon and the Molecular Diversity of Life. What is organic chemistry? Branch of chemistry that studies carbon compounds. Carbon (valence = 4). Nitrogen (valence = 3). Hydrogen (valence = 1). Oxygen (valence = 2). O. H. N.
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Chapter 4 Carbon and the Molecular Diversity of Life
Ch 4 Carbon and the Molecular Diversity of Life • What is organic chemistry? • Branch of chemistry that studies carbon compounds
Carbon (valence = 4) Nitrogen (valence = 3) Hydrogen (valence = 1) Oxygen (valence = 2) O H N C Ch 4 Carbon and the Molecular Diversity of Life • What is organic chemistry? • What do you know about carbon? • Atomic # = 6 • Forms covalent bonds • Tetravalent – 4 valence electrons – forms 4 bonds • Tetravalence makes large, complex molecules possible. • Determines 3D shape of molecules • Compatible with other abundant elements This is also the number of covalent bonds each element can form!!!!
Ch 4 Carbon and the Molecular Diversity of Life • What is organic chemistry? • What do you know about carbon? • How does carbon contribute to molecular diversity? • Carbon skeletons – covalent bonds that link C atoms together & form the skeletal framework of organic molecules
H H H H H H H H C C C C H C H H H H H H C H H H H H H H H H H H H C C C C C C C H H H H H H H H H H H H H H H H H H H C C C C C C C C H H H H H H H H C H H C H C C H H C C H H C C H H C C C H H C H H H Figure 4.5 Variations in carbon skeletons (a) Length Ethane Propane (b) Branching 2-methylpropane (commonly called isobutane) Butane (c) Double bonds 1-Butene 2-Butene (d) Rings Cyclohexane Benzene
Ch 4 Carbon and the Molecular Diversity of Life • What is organic chemistry? • What do you know about carbon? • How does carbon contribute to molecular diversity? • What are hydrocarbons? • Molecules consisting of only hydrogen & carbon • Fossil fuels • Some are biologically important (fats) • Hydrophobic (non-polar) – oil & water don’t mix
Ch 4 Carbon and the Molecular Diversity of Life • What is organic chemistry? • What do you know about carbon? • How does carbon contribute to molecular diversity? • What are hydrocarbons? • What are isomers? - compounds w/ the same molecular formula but w/ different structures & therefore, different properties
H C H H C H H H H H H H H H (a) Structural isomers C C C C C C H H C H C H H H H H H H H H X X H X (b) Geometric isomers C C C C X H H H CO2H CO2H C C (c) Enantiomers H H NH2 NH2 CH3 CH3 L isomer D isomer Figure 4.7 Three types of isomers
Ch 4 Carbon and the Molecular Diversity of Life • What is organic chemistry? • What do you know about carbon? • How does carbon contribute to molecular diversity? • What are hydrocarbons? • What are isomers? • What are functional groups? • Parts of molecules involved in chemical rxns • Molecules added to carbon skeletons that give properties to the macromolecule….carbs, proteins, lipids, nucleic acids
FUNCTIONAL GROUP HYDROXYL CARBONYL CARBOXYL O O OH C C OH (may be written HO ) STRUCTURE In a hydroxyl group (—OH), a hydrogen atom is bonded to an oxygen atom, which in turn is bonded to the carbon skeleton of the organic molecule. (Do not confuse this functional group with the hydroxide ion, OH–.) The carbonyl group( CO) consists of a carbon atom joined to an oxygen atom by a double bond. When an oxygen atom is double-bonded to a carbon atom that is also bonded to a hydroxyl group, the entire assembly of atoms is called a carboxyl group (—COOH). Is polar as a result of the electronegative oxygen atom drawing electrons toward itself. Attracts water molecules, helping dissolve organic compounds such as sugars (see Figure 5.3). Has acidic properties because it is a source of hydrogen ions. The covalent bond between oxygen and hydrogen is so polar that hydrogen ions (H+) tend to dissociate reversibly; for example, A ketone and an aldehyde may be structural isomers with different properties, as is the case for acetone and propanal. FUNCTIONALPROPERTIES H H O O + H+ H C H C C C OH O H H Acetate ion Acetic acid In cells, found in the ionic form, which is called a carboxylate group. Figure 4.10 Exploring some important functional groups of organic compounds
FUNCTIONAL GROUP AMINO SULFHYDRYL PHOSPHATE O H SH N (may be written HS ) P O O H OH STRUCTURE In a phosphate group, a phosphorus atom is bonded to four oxygen atoms; one oxygen is bonded to the carbon skeleton; two oxygens carry negative charges; abbreviated P . The phosphate group (—OPO32–) is an ionized form of a phosphoric acid group (—OPO3H2; note the two hydrogens). The amino group (—NH2) consists of a nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton. The sulfhydryl group consists of a sulfur atom bonded to an atom of hydrogen; resembles a hydroxyl group in shape. Two sulfhydryl groups can interact to help stabilize protein structure (see Figure 5.20). Makes the molecule of which it is a part an anion (negatively charged ion). Can transfer energy between organic molecules. Acts as a base; can pick up a proton from the surrounding solution: FUNCTIONAL PROPERTIES H H N +N H • Methyl group (-CH3) • non-polar H H (nonionized) (ionized) Ionized, with a charge of 1+, under cellular conditions.