Chapter 4 Carbon and the Molecular Diversity of Life

Ch 4 Carbon and the Molecular Diversity of Life 1.What is organic chemistry? -Branch of chemistry that studies carbon compounds

Ch 4 Carbon and the Molecular Diversity of Life 1.What is organic chemistry? 2.What do we 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 H O NC Hydrogen (valence = 1) Oxygen (valence = 2) Nitrogen (valence = 3) Carbon (valence = 4)

Ch 4 Carbon and the Molecular Diversity of Life 1.What is organic chemistry? 2.What do you know about carbon? 3.How does carbon contribute to molecular diversity? Carbon skeletons – covalent bonds that link C atoms together & form the skeletal framework of organic molecules

Figure 4.5 Variations in carbon skeletons H HH H H C HH HHH H H H H H H H H H H H HHH H H H H H H H H H H H H H H HH HH HH HH HHH H H H HH H H H H H H H C C CCC CCCCCCC CCCCCCCC C C C C C C C C C C C C H H H H H H H (a) Length (b) Branching (c) Double bonds (d) Rings Ethane Propane Butane 2-methylpropane (commonly called isobutane) 1-Butene2-Butene CyclohexaneBenzene

Ch 4 Carbon and the Molecular Diversity of Life 1.What is organic chemistry? 2.What do you know about carbon? 3.How does carbon contribute to molecular diversity? 4.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 1.What is organic chemistry? 2.What do you know about carbon? 3.How does carbon contribute to molecular diversity? 4.What are hydrocarbons? 5.What are isomers? - compounds w/ the same molecular formula but w/ different structures & therefore, different properties

Figure 4.7 Three types of isomers 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 H H HH H H H H HH H C CCCC HH C H H H H H C C C C C C C C C (a) Structural isomers (b) Geometric isomers (c) Enantiomers H L isomerD isomer

Ch 4 Carbon and the Molecular Diversity of Life 1.What is organic chemistry? 2.What do you know about carbon? 3.How does carbon contribute to molecular diversity? 4.What are hydrocarbons? 5.What are isomers? 6.What are functional groups? Parts of molecules involved in chemical rxns

FUNCTIONAL GROUP HYDROXYL CARBONYL CARBOXYL OH In a hydroxyl group, a hydrogen atom is bonded to an oxygen atom, which in turn is bonded to the carbon skeleton of the organic molecule. STRUCTURE The carbonyl group 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. C OO C OH PROPERTIES  Is polar as a result of the electronegative oxygen atom drawing electrons toward itself.  Attracts water molecules; helps dissolve organic compounds such as sugars  May be structural isomers with different properties, therefore increasing the reactive diversity of the carbon chain to which it is attach.  Has acidic properties because it is a source of hydrogen ions. (see below)  In cells, found in the ionic form, which is called a carboxylate group. H H C H H C O OH H H C O C OO + H + Acetic acid Acetate ion COMPOUND NAME (w/ example) Alcohol (cholesterol) Ketone (fructose) Aldehyde (ribose) Carboxylic acid (lactic acid)

AMINO SULFHYDRYL PHOSPHATE N H H SH FUNCTIONAL GROUP The amino group 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. 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.  Acts as a base; can pick up a proton from the surrounding solution. (see below) N H H H +N+NH H  Two sulfhydryl groups can interact to help stabilize protein structure.  Makes the molecule of which it is a part an anion (negatively charged ion). Can transfer energy between organic molecules. FUNCTIONAL PROPERTIES COMPOUND NAME (w/ example) Amine (histamine)Thiol (cysteine)Organic phosphate (ATP) ***AMINO ACID = carbon chain with both a carboxyl group AND an amino group***