Biol 1107 Chapter 3 Organic chemistry overview I Organic substances are molecules that have C atoms bound to other atoms to form the backbone of the molecule A C in organic molecules may be bound to C or to other elements 1 Often have long chains of C C bonds a Also commonly forms bonds with H O N S and P 2 Very simple C compounds are not considered organic a Ex CO2 H2CO3 B Properties of C make organic molecules very diverse 1 Has 4 e in its valence shell a Can form 4 covalent bonds to fill its shell i Contrast to O Has 6 valence e Can only form 2 covalent bonds 2 C C bonds are very strong a Excellent for forming backbone of long molecules C C C C C C C 3 Covalent bonds between C atoms can be single double or triple a Share 1 2 or 3 pairs of e respectively ii Triple bonds not common in biology 4 Covalent bonds between C atoms can be flexible or stiff a Single bonds can rotate i Very flexible ii Good for long molecules b Double and triple bonds are stiff i Cannot rotate ii Can give shape C Placement of bonds is very important 1 Isomers molecules with same atoms in different arrangements a Same molecular formula different structural formulas b Slight structural changes can have large effects in chemical physical and biological properties 2 Different types of isomers a Structural isomers same atoms different bond partners i Ex C2H6O can be ethanol or dimethyl ether b Geometric isomers same atoms same bond partners i Different arrangement of atoms around a central double bond ii Has cis and trans forms Ex cis and trans fats c Enantiomers mirror image isomers i Only occur when a C has 4 different atoms bound ii Result from 3D shape of carbon compounds D Functional groups side groups attached to the backbone of an organic molecule 1 Determines behavior of the molecule a Can make a molecule hydrophobic or hydrophilic b Can determine physical state of molecule at a given temp solid liquid or gas 2 Usually written as R side chain a R means remainder i Shorthand so you don t have to draw out the whole molecule when only talking about part of it b Sometimes R can be backbone sometimes R can be side chain i Just shows that something is attached to atoms of interest 3 Important functional groups a Polar side chains make molecules more hydrophilic i R OH hydroxyl group ii R COOH carboxyl group Weakly acidic Found in amino acids iii R COR carbonyl group May be a ketone or aldehyde iv R NH2 amine group Weakly basic Found in amino acids v R PO4 phosphate group Several may be strung together in high energy bonds Found in phospholipids nucleic acids ATP etc b Nonpolar side chains make molecules more hydrophobic i R CH3 methyl group III Many important biological molecules are macromolecules A Macromolecules are polymers 1 Polymers are large molecules made of repeating smaller subunits a Subunits are monomers b Polymerization is the process of joining monomers i Involves a condensation reaction ii Enzyme joins monomers by pulling a H2O molecule out c Reverse reaction is hydrolysis i Polymer split into monomers ii H2O is consumed d Different enzymes perform condensation hydrolysis reactions i Avoids futile loops 2 Important biological macromolecules a Carbohydrates proteins nucleic acids lipids V Carbohydrates A Essential biological molecules 1 Includes monosaccharides disaccharides oligosaccharides polysaccharides B Monosaccharides are simple sugars 1 Hexose monosaccharides with 6 C a Glucose C6H12O6 very abundant carbohydrate i Important as an energy source ii Body closely watches glucose levels b Fructose C6H12O6 another hexose i Extremely sweet tasting found in fruit and honey high fructose corn syrup c Galactose C6H12O6 yet another hexose i Found in dairy products 2 Pentose monosaccharides with 5 C a Ribose sugar in RNA d Deoxyribose sugar in DNA 3 Hexoses and pentoses form rings in solution a Linear when dry b Rings in water C Disaccharides are two monosaccharides joined 1 May be 2 of the same or 2 different a Sucrose glucose fructose b Lactose glucose galactose 2 Formed by condensation reactions 3 Split into monosaccharides during digestion by hydrolysis reactions D Polysaccharides polymers of many monosaccharides 1 Generally 40 to several thousand monomers long a May be branched or unbranched b Several very important polysaccharides 2 Starch main energy storage molecule in plants a Polymer of glucose i Amylose linear polymer ii Amylopectin branched polymer b Virtually every organism can hydrolyze starch for energy 3 Glycogen main energy storage compound in animals a Sometimes called animal starch b Polymer of glucose i Highly branched c Stored mainly in liver and muscle cells i Broken down to glucose when we need more energy 4 Cellulose structural carbohydrate found in plants a Most abundant carb on earth b Forms rigid wall around plant cells i Forms long strong bundles of fiber ii Gives them shape c Polymer of glucose d Cannot be digested by any animal i Ruminants have bacteria in their gut that do it ii Attempts to do this for biofuel purposes 5 Other important carbohydrates a N acetyl glucosamine modified carbohydrate in chitin i Main component of insect and arthropod shells b Glucosamine glucose with a R OH R NH2 change c Glycoproteins proteins with carbohydrate modifications i Precursor for joint cartilage i Very large diverse family ii Main component of mucus d Glycolipids lipids with carbohydrate modifications i Common parts of plasma membrane VI Lipids fats or fat like substances A Composed mainly of C and H 1 Typically very hydrophobic a Important for their function in membranes 2 Contain 2x the energy of similar amount of carbs or proteins a Makes them efficient for long term energy storage B Glycerides are the most abundant 1 Made of a glycerol backbone and 1 3 fatty acid chains a Fatty acids are long unbranched hydrocarbon chains 2 Fatty acids are joined to glycerol via condensation reactions a Occurs stepwise b Monoglycerides have 1 fatty acid c Diglycerides have 2 fatty acids d Triglycerides have 3 fatty acids i These are the most common glycerides ii Main component of vegetable oil and animal fat 3 Saturation of glycerides measure of how many double bonds are present in fatty acid chains a Saturated no double bonds present i Contains the maximum amount of H in the hydrocarbon ii ie saturated for H b Monounsaturated contains exactly 1 double bond c Polyunsaturated contains 2 double bonds d Saturation levels affect physical properties i Ex melting temp butter vs vegetable oil ii