1. What Is Biotechnology?
bio—the use of biological processes;andtechnology—tosolveproblemsormake useful products.
Usingbiological processesishardlyanoteworthyevent.We begangrowingcropsandraisinganimals10,000 years
ago to provide astable supplyof foodandclothing.We have usedthe biological processesof microorganismsfor
6,000 yearsto make useful foodproducts,suchasbreadand cheese,andtopreserve dairyproducts.Duringthe
1960s and ’70s our understandingof biologyreachedapointwhere we couldbegintouse the smallestpartsof
organisms—theirbiological molecules—inadditiontousingwhole organisms.
A more appropriate definitioninthe newsense of the wordisthis:“New”Biotechnology—theuse of cellularand
biomolecularprocessestosolve problemsormake useful products.Biotechnologyisacollectionof technologiesthat
capitalize onthe attributesof cells,suchastheirmanufacturingcapabilities,andputbiological molecules,suchas
DNA and proteins,toworkfor us.
CellsandBiological MoleculesCellsare the basicbuildingblocksof all livingthings.The simplestlivingthings,suchas
yeast,consistof a single,self-sufficientcell.Complex creaturesmore familiartous,such as plants,animalsand
humans, are made of manydifferentcell types,eachof whichperformsaveryspecifictask.Inspite of the
extraordinarydiversityof cell typesinlivingthings,whatismoststrikingistheirremarkable similarity.Thisunityof
life atthe cellularlevelprovidesthe foundationforbiotechnology.
Here are a fewof the newbiotechnologiesthatuse cellsandbiological moleculesandexamplesof theirapplications
inmedicine,agriculture,foodprocessing,industrial manufacturingandenvironmentalmanagement.
BioprocessingTechnology
The oldestof the biotechnologies,bioprocessingtechnology,useslivingcellsorthe molecularcomponentsof their
manufacturingmachinerytoproduce desiredproducts.The livingcellsmostcommonlyusedare one-celled
microorganisms,suchasyeastand bacteria;the biomolecularcomponentswe use mostoftenare enzymes,which
are proteinsthatcatalyze biochemical reactions.A formof bioprocessing,microbialfermentation,hasbeenusedfor
thousandsof years—unwittingly—tobrewbeer,make wine,leavenbreadandpickle foods.
In the mid-1800s, whenwe discoveredmicroorganismsandrealizedtheirbiochemical machinerywasresponsible for
these useful products,we greatlyextendedouruse of microbial fermentation.We now relyonthe remarkably
diverse manufacturingcapabilityof naturallyoccurringmicroorganismstoprovide uswithproductssuchas
antibiotics,birthcontrol pills,aminoacids,vitamins,industrial solvents,pigments,pesticidesandfood-processing
aids.Today,we are usingrecombinantDNA technology,coupledwithmicrobial fermentation,tomanufacture awide
range of bio-basedproductsincludinghumaninsulin,the hepatitisBvaccine,the calf enzyme usedincheese-making,
biodegradableplastics,andlaundrydetergent enzymes.Bioprocessingtechnologyalsoencompassestissue
engineeringandmanufacturingaswell asbiopharmaceutical formulationanddelivery.
Monoclonal Antibodies
Monoclonal antibodytechnologyusesimmune-systemcellsthatmake proteinscalledantibodies.We have all
experiencedthe extraordinaryspecificityof antibodies:Those thatattacka fluvirusone winterdonothingtoprotect
us froma slightlydifferentfluvirusthe nextyear.Specificityreferstothe factthat biological moleculesare designed
so that theybindtoonlyone molecule.
The specificityof antibodiesalsomakesthempowerful diagnostictools.Theycanlocate substancesthatoccur in
minute amountsandmeasure themwithgreataccuracy.For example,we use monoclonal antibodies tolocate
environmental pollutants. Detectharmful micro-organismsinfood. distinguishcancercellsfromnormal cells.
Diagnose infectiousdiseasesinhumans,animalsandplantsmore quicklyandmore accuratelythaneverbefore.In
additiontotheirvalue asdetectiondevices,monoclonalantibodies(MAbs) canprovide uswithhighlyspecific
therapeuticcompounds.
Monoclonal antibodiesjoinedtoatoxincan selectivelydeliverchemotherapytoacancer cell while avoidinghealthy
cells.We are developing monoclonal antibodiestotreatorgan-transplantrejectionandautoimmune diseasesby
2. targetingthemspecificallytothe type of immune systemcell responsible forthese attacks,leavingintactthe other
branchesof the immune system.
Monoclonal antibodies are usedtopreventacute rejectionof organtransplants. MAbsUSED TO KILL OR INHIBIT
CANCERCELLS
Cell Culture
Cell culture technologyisthe growingof cellsoutsideof livingorganisms.
PLANT CELL CULTURE An essentialstepincreatingtransgeniccrops,plantcell culture alsoprovidesuswith
an environmentallysoundandeconomicallyfeasible optionforobtainingnaturallyoccurringproductswith
therapeuticvalue.
INSECT CELL CULTURE Insectcell culture can broadenouruse of biological control agentsthatkill insectpests
withoutharmingbeneficial insectsorhavingpesticidesaccumulate inthe environment.Eventhoughwe have
recognizedthe environmental advantagesof biological control formanydecades,manufacturingbiological control
productsin marketable amountshasbeenimpossible.Insectcell culture removesthese manufacturingconstraints.
In addition,likeplantcell culture,insectcell culture isbeinginvestigatedasaproductionmethodof therapeutic
proteins.Insectcell culture is alsobeinginvestigatedforthe productionof VLP(viruslike particle) vaccinesagainst
infectiousdiseasessuchasSARSand influenza,whichcouldlowercostsandeliminatethe safetyconcernsassociated
withthe traditional eggbasedprocess.A patientspecificcancervaccine thatutilizesinsectcell culture hasreached
Phase IIIclinical trials.
MAMMALIANCELL CULTURE Livestockbreedinghasusedmammaliancell cultureasanessential tool fordecades.
Eggs and sperm,takenfromgeneticallysuperiorbullsandcows,are unitedinthe lab,and the resultingembryosare
grownin culture before beingimplantedinsurrogate cows.A similarformof mammaliancell culture hasalsobeen
an essential componentof the humaninvitrofertilizationprocess.Ouruse of mammaliancell culturenowextends
well beyondthe brief maintenance of cellsinculture forreproductivepurposes.Mammaliancell culturecan
supplement—andmayone dayreplace—animal testingtoassessthe safetyandefficacyof medicines.Like plant cell
culture andinsectcell culture,we are relyingonthe manufacturingcapacityof mammaliancellstosynthesize
therapeuticcompounds,inparticular,certainmammalianproteinstoocomplex tobe manufacturedbygenetically
modifiedmicroorganisms.Forexample,monoclonalantibodiesare producedthroughmammaliancell culture.
Scientistsare alsoinvestigatingthe use of mammaliancell culture asaproductiontechnologyforvaccines.
Researchersalsoare workingonwaysto harveststemcellsfromplacentasandfromfat.Some are lookingatcellular
reprogrammingasa way to getspecializedbodycells,likeskincells,toreverttoa primordial state sothat theycan
be coaxedintovarioustypesof tissues.Embryonicstemcellsare alsounderstudyaspotential therapies.Asthe
name suggests,embryonicstemcellsare derivedfromembryos—specificallythose thatdevelopfromeggsthathave
beenfertilizedinvitro(inaninvitrofertilizationclinic) andthendonatedbyconsentforresearchpurposes.The
embryosare typicallyfourorfive daysoldand are each a hollow microscopicball of cellscalledthe blastocyst.
The potential value of stemcell therapyandtissue engineeringcanbestbe realizedif the therapeuticstemcellsand
the tissuesderivedfromthemare geneticallyidentical tothe patientreceivingthem.
RecombinantDNA Technology
RecombinantDNA technologyisviewedbymanyasthe cornerstone of biotechnology.The termrecombinantDNA
literallymeansthe joiningorrecombiningof twopiecesof DNA fromtwodifferentspecies.Humansbeganto
preferentiallycombine the geneticmaterial of domesticatedplantsandanimalsthousandsof yearsagoby selecting
whichindividualswouldreproduce.Bybreedingindividualswithvaluable genetictraits while excludingothersfrom
reproduction,we changedthe geneticmakeupof the plantsandanimalswe domesticated.Now,inadditiontousing
selectivebreedingtocombine valuablegeneticmaterial fromdifferentorganisms,we combine genesatthe
molecularlevel usingthe more precisetechniquesof recombinantDNA technology.Geneticmodificationthrough
selectivebreedingandrecombinantDNA techniquesfundamentallyresemble eachother,butthere are important
differences:nGeneticmodificationusingrecombinantDNA techniquesallowsustomove single geneswhose
3. functionswe knowfromone organismtoany other.n Inselective breeding,large setsof genesof unknownfunction
are transferredbetweenrelatedorganisms.
By makingour manipulationsmore preciseandouroutcomesmore certain,we decrease the riskof producing
organismswithunexpectedtraitsandavoidthe time-consuming,trial-and-errorapproachof selective breeding.By
increasingthe breadthof speciesfromwhichwe canobtainuseful genes, we canaccessall of nature’sgenetic
diversity.Techniquesformakingselective breedingmore predictable andprecisehave beenevolvingoverthe years.
In the early1900s, Hugo DeVries,Karl CorrensandEricTshermarkrediscoveredMendel’slawsof heredity.In1953,
JamesWatsonand FrancisCrick deducedDNA’sstructure fromexperimentalcluesandmodel building.In1972, Paul
Berg andcolleaguescreatedthe firstrecombinantDNA molecules,usingrestrictionenzymes.Tenyearslater,the
firstrecombinant DNA-baseddrug(recombinanthumaninsulin) wasintroducedtothe market.By2000 the human
genome hadbeensequencedandtodaywe use recombinantDNA techniques,inconjunctionwithmolecularcloning
to n produce newmedicinesandsafervaccines.ntreat some geneticdiseases.nenhance biocontrol agentsin
agriculture.
n increase agricultural yieldsanddecreaseproductioncosts.ndecrease allergy-producingcharacteristicsof some
foods.nimprove food’snutritional value.ndevelopbiodegradableplastics.ndecrease waterandairpollution.n
slowfoodspoilage.ncontrol viral diseases.ninhibitinflammation.
Cloning
Cloningtechnologyallowsustogenerate a populationof geneticallyidentical molecules,cells,plantsoranimals.
Because cloningtechnologycanbe usedto produce molecules,cells,plantsandsome animals,itsapplicationsare
extraordinarilybroad.Anylegislativeorregulatoryactiondirectedat“cloning”musttake greatcare indefiningthe
termpreciselysothatthe intendedactivitiesandproductsare coveredwhile othersare notinadvertentlycaptured.
MOLECULAR OR GENECLONING Molecularor gene cloning,the processof creatinggeneticallyidentical DNA
molecules,providesthe foundationof the molecularbiologyrevolutionandis a fundamental andessential tool of
biotechnologyresearch,developmentandcommercialization.Virtuallyall applicationsinbiotechnology,fromdrug
discoveryanddevelopmenttothe productionof transgeniccrops,dependongene cloning.
Virtuallyall applicationsinbiotechnology,fromdrugdiscoveryanddevelopmenttothe productionof transgenic
crops,dependongene cloning.
The researchfindingsmade possible throughmolecularcloninginclude identifying,localizingandcharacterizing
genes;creatinggeneticmapsandsequencingentiregenomes;associatinggeneswithtraitsanddeterminingthe
molecularbasisof the trait.For a full discussion,see page 27.
ANIMAL CLONING Animal cloninghashelpedustorapidlyincorporate improvementsintolivestockherdsfor
more than twodecadesandhas beenan importanttool forscientificresearcherssincethe 1950s. Althoughthe 1997
debutof Dolly,the clonedsheep,broughtanimalcloningintothe publicconsciousness,the productionof ananimal
clone wasnot a newdevelopment.Dollywasconsideredascientificbreakthroughnotbecause she wasaclone,but
because the source of the geneticmaterial thatwasusedto produce Dollywasan adultcell,notan embryonicone.
RecombinantDNA technologies,inconjunctionwithanimal cloning,are providinguswithexcellentanimal models
for studyinggeneticdiseases,agingandcancerand,inthe future,will helpusdiscoverdrugsandevaluate other
formsof therapy,suchas gene andcell therapy.Animal cloningalsoprovideszooresearcherswithatool forhelping
to save endangeredspecies.There are twodifferentwaystomake an exactgeneticcopyof an organismsuchas a
sheepora laboratorymouse.Artificial embryotwinning(AET) isthe old-fashionedwaytoclone.AETmimicsthe
natural processof creatingidentical twins,onlyinaPetri dishratherthanthe mother’swomb.Researchersmanually
separate a veryearlyembryointoindividualcellsandthenallow eachcell todivideanddeveloponitsown.The
resultingembryosare placedintoasurrogate mother,where theyare carriedtotermand delivered.Since all the
embryoscome fromthe same zygote,theyare geneticallyidentical.Somaticcell nucleartransfer(SCNT) involvesthe
isolationof asomatic(body) cell,whichisanycell otherthenthose usedforreproduction(spermandegg,knownas
the germ cells).Inmammals,everysomaticcell hastwocomplete setsof chromosomes,whereasthe germcells
have onlyone complete set.Tomake Dolly,scientiststransferredthe nucleusof asomaticcell takenfroman adult
female sheepandtransferredittoan eggcell fromwhichthe nucleushadbeenremoved.Aftersome chemical
4. manipulation,the eggcell,withthe newnucleus,behavedlike afreshlyfertilizedzygote.Itdevelopedintoan
embryo,whichwasimplantedintoasurrogate motherandcarriedto term.
ProteinEngineering
Proteinengineeringtechnologyisused,ofteninconjunctionwithrecombinantDNA techniques,toimprove existing
proteins,suchasenzymes,antibodiesandcell receptors,andtocreate proteinsnotfoundinnature.These proteins
may be usedindrug development,foodprocessingandindustrialmanufacturing.
The most pervasive usesof proteinengineeringtodate are applicationsthatalterthe catalyticpropertiesof enzymes
to developecologicallysustainable industrial processes.Enzymesare environmentallysuperiortomostother
catalystsusedinindustrial manufacturingbecause,asbiocatalysts,theydissolve inwaterandwork bestatneutral
pH and comparativelylowtemperatures.Inaddition,becausebiocatalystsare more specificthanchemical catalysts,
theyalsoproduce fewerunwantedbyproducts.The chemical,textile,pharmaceutical,pulpandpaper,foodand
feed,andenergyindustriesare all benefitingfromcleaner,more energy-efficientproductionmade possible by
incorporatingbiocatalystsintotheirproductionprocesses.The characteristicsthatmake biocatalysts
environmentallyadvantageousmay,however,limittheirusefulnessincertainindustrial processes.Forexample,
mostenzymesfall apartat hightemperatures.Scientistsare circumventingtheselimitationsbyusingprotein
engineeringtoincrease enzyme stabilityunderharshmanufacturingconditions.Inaddition toindustrial applications,
medical researchershave usedproteinengineeringtodesignnovel proteinsthatcanbindto and deactivate viruses
and tumor-causinggenes;create especiallyeffectivevaccines;andstudythe membrane receptorproteinsthatare
so oftenthe targetsof pharmaceutical compounds.Foodscientistsare usingproteinengineeringtoimprove the
functionalityof plantstorage proteinsanddevelopnew proteinsasgellingagents.Inaddition,new proteinsare
beingdevelopedtorespondtochemical andbiological attacks.Forexample,hydrolasesdetoxifyavarietyof nerve
agentsas well ascommonlyusedpesticides.Enzymesare safe toproduce,store anduse,makingthemaneffective
and sustainable approachtotoxicmaterialsdecontamination.
Biosensors
Biosensortechnologycouplesourknowledge of biologywithadvancesinmicroelectronics.A biosensoriscomposed
of a biological component,suchasa cell,enzyme orantibody,linkedtoa tinytransducer—adevice poweredbyone
systemthatthensuppliespower(usuallyinanotherform) toa secondsystem.Biosensorsare detectingdevicesthat
relyon the specificityof cellsandmoleculestoidentifyandmeasure substancesatextremelylow concentrations.
Whenthe substance of interestbinds withthe biological component,the transducerproducesanelectrical oroptical
signal proportional tothe concentrationof the substance.Biosensorscan,forexample,nmeasure the nutritional
value,freshnessandsafetyof food.nprovide emergencyroom physicianswithbedsidemeasuresof vital blood
components.nlocate andmeasure environmentalpollutants.ndetectandquantifyexplosives,toxinsand
biowarfare agents.
Nanobiotechnology
Nanotechnology,whichcame intoitsownin2000 withthe birthof the National NanotechnologyInitiative,isthe
nextstopinthe miniaturizationpaththatgave usmicroelectronics,microchipsandmicrocircuits.The word
nanotechnologyderivesfromnanometer,whichisone-thousandthof amicrometer(micron),orthe approximate
size of a single molecule.Nanotechnology—the study,manipulationandmanufacture of ultra-small structuresand
machinesmade of as fewasone molecule—wasmade possiblebythe developmentof microscopictoolsforimaging
and manipulatingsinglemoleculesandmeasuringthe electromagneticforcesbetweenthem.Nanobiotechnology
joinsthe breakthroughsinnanotechnologytothose inmolecularbiology.Molecularbiologistshelp
nanotechnologistsunderstandandaccessthe nanostructuresandnanomachinesdesignedby4 billionyearsof
evolutionaryengineering—cell machineryandbiological molecules.Exploitingthe extraordinarypropertiesof
biological moleculesandcell processes,nanotechnologistscanaccomplishmanygoalsthatare difficultorimpossible
to achieve byothermeans.Forexample,ratherthanbuildsiliconscaffoldingfornanostructures,DNA’sladder
structure providesnanotechnologistswithanatural frameworkforassemblingnanostructuresanditshighlyspecific
bondingpropertiesbringatomstogetherinapredictable patterntocreate a nanostructure.Nanotechnologistsalso
5. relyon the self-assemblingpropertiesof biological moleculestocreate nanostructures,suchaslipidsthat
spontaneouslyformliquidcrystals.
Most appropriately,DNA, the informationstorage molecule,mayserve asthe basisof the nextgenerationof
computers.
DNA has beenusednotonlyto buildnanostructuresbutalsoasan essential componentof nanomachines.Most
appropriately,DNA, the informationstorage molecule,mayserve asthe basisof the nextgenerationof computers.
As microprocessorsandmicrocircuitsshrinktonanoprocessorsandnanocircuits,DNA moleculesmountedonto
siliconchipsmayreplace microchipswithelectronflow-channelsetchedinsilicon.Suchbiochipsare DNA-based
processorsthatuse DNA’sextraordinaryinformationstorage capacity.Conceptually,theyare verydifferentfromthe
DNA chipsdiscussedbelow.Biochipsexploitthe propertiesof DNA tosolve computational problems;inessence,
theyuse DNA to do math.Scientistshave shownthat1,000 DNA moleculescansolve infourmonthscomputational
problemsthatwouldrequire acenturyfora computerto solve.Otherbiological moleculesare assistinginour
continual questtostore and transmit more informationinsmallerplaces.Forexample,some researchersare using
light-absorbingmolecules,suchasthose foundinourretinas,toincrease the storage capacityof CDs a thousand-
fold.Some applicationsof nanobiotechnologyinclude nincreasing the speedandpowerof disease diagnostics.n
creatingbio-nanostructuresforgettingfunctional moleculesintocells.nimprovingthe specificityandtimingof drug
delivery.nminiaturizingbiosensorsbyintegratingthe biological andelectroniccomponentsintoasingle,minute
component.nencouragingthe developmentof greenmanufacturingpractices.MicroarraysMicroarray technologyis
transforminglaboratoryresearchbecause itallowsustoanalyze tensof thousandsof samplessimultaneously.
Researcherscurrentlyuse microarraytechnologytostudygene structure andfunction.Thousandsof DNA orprotein
moleculesare arrayedonglassslidestocreate
