Explainer:Whatisagene?
ByTheConversation,adaptedbyNewselastaffon03.28.17 Word Count414
Level 600L
TOP:DNAisfoundintheformofadoublehelix.OurDNAmakesupourgeneswhichplayanimportantroleindetermining physicaltraitslikethecolorofoureyesorhair.PhotofromGettyImages.MIDDLE:AnillustrationofGregorMendel'sfamous peaflowerexperiment.Thischartshowstworedpeaplantscrossingtohaveredandwhitepeafloweroffspring.Photofrom WikimediaCommons.BOTTOM:ThehumangenomeiscomprisedofmillionsofDNApairssuchastheseillustrated.The HumanGenomeProjectworkstoidentifyallofthem.PhotofromWikimediaCommons
Themeaningoftheword“gene”canbeconfusing.Onereasonforthisisthatpeopleusedthe wordbeforewereallyknewwhatagenewas.Atthetime,weonlyknewwhatgenesdid.
Weknewthatchildrenlookliketheirparents.Forexample,parentswithredhairusuallyhave childrenwithredhair.Parentspassonqualitiestotheirchildren.Weknewthatthesequalities werepassedonthroughgenes.Still,wedidnotquiteknowhowgenesworked.
Over time, the meaning of the word gene has changed.
Gregor Mendel First Discovered How Genes Work
GregorMendelfirstexperimentedwithgenesinthe1850s.Thatwasabout150yearsago. Mendelshowedthatparentspassonqualitiestotheirchildren.
Mendelcrossedaredflowerpeawithawhiteflowerpea.Thisdidnotmakepinkflowers.It madeflowersthatwereeitherwhiteorred.
Childrengetqualitiesfrombothparents.Someofthesequalitiesseemtoblendtogether.But Mendelshowedthatthisisnotthecase.Heshowedthataqualitycouldgofromoneparentto a child. This is why the color of the pea flowers did not blend. The flowers either looked like oneparentortheother.
So Mendel realized that each quality comes from a gene. He did not use the word "gene," though.ThewordwasfirstusedbyWilhelmJohannsenin1909.Johannsensaidgeneswere whatgaveplantsandanimalscertainqualities.
Genes Are Pieces Of DNA That Make Up Proteins
Later,scientistsdiscoveredthatgenesweremadeofDNA.DNAcontainsinformationthattells thebodyhowtogrowandwork.Itisthebasicbuildingblockoflife.
Whatexactlywasagene,though?AscientistnamedFrancisCrickshowedhowDNAcould make something called RNA. RNA could make proteins. A protein is a tool that does somethinginyourbody.Oneimportantproteinishemoglobin.Itcarriesoxygeninyourblood.
This gave us our first clear meaning. A gene is a piece of DNA that makes a protein tool.
Nowwehaveameaningforagene.GenesarepiecesofDNAthatcanmakeaproteintool. Theycanalsomakeaquality.Forexample,theycangiveapeafloweritsredcolor.
Weknowwehavemanygenes.Butwestilldonotknowhowquitehowmany. Aswekeeplearning,wearesuretodiscovernewgenes.