Chemistry of Carbon

Chemistry of Cells

1

The importance of CarbonAll of life is built on carbon Cells ~72% H2O ~25% carbon compoundscarbohydrateslipidsproteins nucleic acids~3% salts Na, Cl, K

2Why do we study carbon -- is it the most abundant element in living organisms?H & O most abundantC is the next most abundant

Chemistry of LifeOrganic chemistry is the study of carbon compoundsC atoms are versatile building blocksbonding properties4 stable covalent bonds

HHCHH3Carbon chemistry = organic chemistry

Why is it a foundational atom?What makes it so important?

Cant be a good building block if you only form 1 or 2 bonds.

Complex molecules assembled like TinkerToys4Like sugars: C6H12O6But can be arranged in different ways-glucose-galactose-dextrose

HydrocarbonsCombinations of C & Hnon-polar not soluble in H2Ohydrophobicstablevery little attraction between moleculesa gas at room temperaturemethane(simplest HC)5Hydrocarbons can grow

6IsomersMolecules with same molecular formula but different structures (shapes) different chemical propertiesdifferent biological functions

6 carbons6 carbons6 carbons7Same formula but different structurally & therefore different functionally. Molecular shape determines biological properties.

Ex. Isomers may be ineffective as medicines

Form affects functionStructural differences create important functional significanceamino acid alanineL-alanine used in proteinsbut not D-alaninemedicinesL-version activebut not D-versionsometimes withtragic results

stereoisomers8Form affects functionThalidomide prescribed to pregnant women in 50s & 60s reduced morning sickness, butstereoisomer caused severe birth defects

9Diversity of moleculesSubstitute other atoms or groups around the carbonethane vs. ethanolH replaced by an hydroxyl group (OH)nonpolar vs. polargas vs. liquidbiological effects!ethane (C2H6)

ethanol (C2H5OH)

10Functional groupsParts of organic molecules that are involved in chemical reactionsgive organic molecules distinctive properties hydroxyl amino carbonyl sulfhydryl carboxyl phosphateAffect reactivitymakes hydrocarbons hydrophilic increase solubility in water

11Viva la difference!Basic structure of male & female hormones is identicalidentical carbon skeleton attachment of different functional groupsinteract with different targets in the bodydifferent effects

12For example the male and female hormones, testosterone and estradiol, differ from each other only by the attachment of different functional groups to an identical carbon skeleton.HydroxylOHorganic compounds with OH = alcohols names typically end in -olethanol

13

CarbonylC=O O double bonded to Cif C=O at end molecule = aldehydeif C=O in middle of molecule = ketone

14

Carboxyl COOH C double bonded to O & single bonded to OH groupcompounds with COOH = acidsfatty acidsamino acids

15

Amino-NH2 N attached to 2 Hcompounds with NH2 = aminesamino acidsNH2 acts as base ammonia picks up H+ from solution

16Sulfhydryl SH S bonded to Hcompounds with SH = thiolsSH groups stabilize the structure of proteins

17

Phosphate PO4P bound to 4 O connects to C through an Olots of O = lots of negative chargehighly reactivetransfers energy between organic molecules ATP, GTP, etc.

18MacromoleculesBuilding Blocksof Life2007-2008

19MacromoleculesSmaller organic molecules join together to form larger moleculesmacromolecules4 major classes of macromolecules:carbohydrateslipidsproteinsnucleic acids

20

H2OHOHOH HHHOPolymersLong molecules built by linking repeating building blocks in a chain monomers building blocksrepeated small units covalent bondsDehydration synthesis21 great variety of polymers can be built from a small set of monomers monomers can be connected in many combinations like the 26 letters in the alphabet can be used to create a great diversity of words each cell has millions of different macromolecules

H2OHOHOH HHHOHow to build a polymerSynthesis joins monomers by taking H2O outone monomer donates OHother monomer donates H+ together these form H2Orequires energy & enzymesenzymeDehydration synthesisCondensation reaction22

H2OHOHHOHHOHHow to break down a polymerDigestionuse H2O to breakdown polymers reverse of dehydration synthesiscleave off one monomer at a timeH2O is split into H+ and OHH+ & OH attach to endsrequires enzymesreleases energyHydrolysisDigestionenzyme23Most macromolecules are polymers build:condensation (dehydration) reaction breakdown:hydrolysisAn immense variety of polymers can be built from a small set of monomers