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GENE-iusStudyGuide

ThisstudyguideisintendedtohelpGENE-iuscoachesunderstandthetopicstheeventwillcoverandthelevelofcomprehensionexpectedforthosetopics.Itisrecommendedandexpectedthatadditionalmaterials,websitesandactivitiesbeusedtohelppreparetheteamsforthisevent.

I. BasicCell/MolecularBiology–Studentsshouldonlyfocusonthefollowingbasicconceptsofeukaryotic(willsticktoanimal)cells.

A. Partsofthecell

1. Whatisacell?–Acellisthebasicunitoflife.Alllivingthingsaremadeupofonecell(likebacteriaoryeast)ormanycells(likehumans).Eachcellislikeaminifactorywithindividualparts(organelles)workingtogethertocarryoutspecificfunctions.

2. Cellmembrane–Thecellmembraneistheoutermostlayerofthecell.Itislikeabagthatholdseverythingtogether.Itcontainsopeningsthatallowthingstoenterandleavethecell.Itisliketheshippingandreceivingdepartmentinthecellfactory.

3. Cytoplasm–Thecytoplasmisaliquidsubstancethatfillsupthespaceinsidethemembrane.Itholdsalltheotherorganellesofthecellinplaceandhelpsgivethecellshape.Itislikethebusyfactoryfloorwiththingsmovingabout.

4. Nucleus–Thenucleusisthe“brains”ofthecell.Itisthecontroloffice.Ithousesthegeneticmaterialofthecell(DNA/genes/chromosomes).Ithasitsownmembrane,thenuclearmembrane.

5. Ribosomes-The“workers”ofthecellfactory.RibosomesusetheinstructionsstoredinDNAtoassembleproteins.Proteinsarethebuildingblocksandmachinesthecellusestocarryoutitsmanyfunctions.

RIBOSOME

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http://www.ducksters.com/science/the_cell.php http://www.biology4kids.com/files/cell_main.html

B. BasicMolecularBiology

1. DNA(deoxyribonucleicacid)–ADNAmoleculecontainstwolongstrandswoundtogethertoformadoublehelix.Eachstrandhasa“backbone”madeupofphosphateanddeoxyribose(asugar).Extendingfromthisbackbonearefourpossiblebases;adenine(A),thymine(T),cytosine(C)orguanine(G).Aphosphate,adeoxyriboseandabasemakeupanucleotide.NucleotidesarethebasicbuildingblocksofaDNAmolecule.EachstrandoftheDNAmoleculeislikehalfofaladderwithnucleotidesstackedupontopofeachother.ThetwostrandsofDNAareheldtogetherbytheinteractionor“basepairing”ofthesenucleotides.

a) Basepairingrule–adeninewillonlypairwiththymine(A-T)andguaninewillonlypairwithcytosine(G-C).

b) Antiparalleldoublehelix–Antiparallelisatermthatmeansyouhavetwostrandsthataresidebysidebutruninoppositedirections.ADNAmoleculeiscomprisedoftwostrandsthatarewoundtogetherandjoinedbythebasepairingofthenucleotidesbuteachofthetwostrandsrunsindifferentdirections.TheendofaDNAstrandthathasthephosphateisreferredtoasthe5’(5prime)end.Theendofthatstrandwithasugar(deoxyribose)isreferredtoasthe3’(3prime)end.Inthediagramsbelow,youcanseethatonestrandruns5’to3’whilethecomplementarystrandruns3’to5’.

Teamsdonotneedtounderstandthechemicalstructurethatresultsinthe designationoftheendsas5’or3’.

c) DNAstructureidentification(AppendixA)–Studentsshouldbeabletoidentifythemajorpartsdescribedinthisstudyguide.Theyshouldbepreparedtolabeladiagramoridentifypartsona3Dmodel.StudentsarenotexpectedtounderstandthechemicalstructureofDNAbeyondwhatisdescribedabove.

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2. Genes–AgeneisaspecificsectionofDNAthatcontainsalltheinformationor“code”tomakeaspecificprotein.Proteinsarelikemachinesthatworktogethertocarryoutallthefunctionsacellneedstogetdonetostayalive.Eachproteinismadeupofaminoacidsarrangedinaspecificorder.Thespecificorderoftheaminoacidsinaproteiniscodedbythespecificsequenceofthenucleotides,A,C,G,andTinthegeneforthatprotein.IfthereisachangeintheDNAsequenceinageneorpartofthesequenceismissingitcansometimescausewhatisreferredtoasamutation.Forexample,iftheDNAsequenceforaspecificgenehasanA(adenine)whereitissupposedtohaveaC(cytosine),theinstructionswillbewrongandthecellwillformadefective“part”orprotein.(Seesicklecelldiseasebelow)

http://www.ducksters.com/science/biology/dna.php

a) CodonReading–TheDNAcodeofaspecificgeneisread3nucleotidesatatimeorasatriplet.Thesetripletsarecalledcodons.Eachcodoncorrespondstoaspecificaminoacid.Individualaminoacidsarethebuildingblocksofproteins.Thinkofageneasalongsentencemadeupof3letterwords.Eachwordcorrespondstoaspecificaminoacid.Theseaminoacidsarethenstrungtogetherinaspecificordertomakeaspecificprotein.Thereisevenacodonthatrepresentsa“stop”inthesequence,whichisanalogoustoaperiod.AlthoughthefullgeneforaproteincontainsadditionalDNAsequencesthe“coding”sequencereferstothatportionthatspecificallycodesfortheaminoacidsoftheprotein.ThiscodingsequencewillstartwiththecodonATG,thecodonfortheaminoacidMethionine.AppendixBcontainstheactualDNAcodontablethestudentswillbegivenduringtheevent.Italsocontainsseveralexamplesofgenesequencesandthecorrespondingaminoacidsequenceoftheproteinthatsequencewouldproduce.Noticethatseveralcodonsrepresentthesameaminoacidsandthereare3separatestopcodons.Forthesakeofsimplicity,whenthetermgeneisusedinthiseventitisreferringtothecodingsequenceportionofthegene.5thgradeonly–Pleasesee“transcription”formoredetailedinformationaboutcodonreadingandRNA.

b) Mutations–Asmentionedabove,ifanucleotidesequenceofageneischangeditmayresultinamutation.Themutationiscausedbecausethatnucleotidechangemayresultinadifferentcodon,whichwillthenresultindifferentaminoacidbeingplacedatthatpositionintheprotein.Sometimes,onesingleaminoacidchangeinaproteincanresultinacompletelyorpartiallydefectiveprotein.Thisisthecaseforthegeneticdiseaseinhumansknownassicklecelldisease.Sicklecelldiseaseaffectsmillionsofpeopleworldwideandaffects70,000to80,000Americans.Peoplewithsicklecelldiseasehaveamutationinhemoglobin,aproteinfoundinredbloodcellsandnecessarytodeliveroxygentoallthecellsthroughoutthebody.Thedefectivehemoglobinwillstarttoclumptogetherundersomeconditionscausingtheredbloodcellstoformasickleshape.Thesesickledredbloodcellscandieleadingtoaconditionknownasanemiaorthesesicklecellsmaygetstuckinthesmallbloodvesselsresultinginpainandotherseriousmedicalcomplications.Thisgeneticdiseaseiscausedbyasinglenucleotidechangeresultinginanaminoacidchangeinthehemoglobinprotein(seebelow).Studentsdonotneedtoknowthemedicaldetailsofsicklecelldisease.Itistoserveasareallifeexampleofageneticmutation.

http://kidshealth.org/en/teens/sickle-cell-anemia.html

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GeneticmutationcausingSickleCellDisease

c) Typesofmutations

(1) Missense–asinglenucleotidechangethatresultsinthesubstitutionofoneaminoacidforanotherintheproteinmadebythegene.Amissensemutationmayormaynotresultinadefectiveprotein.Itdependsonthetypeofaminoacidbeingchangedandthelocationofthataminoacidintheprotein.Thesicklecellexampleaboveisamissensemutation.Teamswillnothavetodeterminetheimpactofanaminoacidchange.

(2) Synonymous-asinglenucleotidechangethatdoesnotresultinanaminoacidchangeinthefinalproteinduetotheredundancyinthegeneticcode(multiplecodonscodeforthesameaminoacid).

(3) Nonsense–asinglenucleotidechangeintheDNAsequenceofageneresultinginacodonforastopsignal.Thistypeofmutationresultsinashortenedproteinthatmayfunctionimproperlyornotatall.

(4) Frameshiftmutations-Frameshiftmutationsareduetoeitherinsertionsordeletionsofnucleotidesinthecodingregionofthegene.Whenoneormorenucleotidesareeitherinsertedordeletedthereisachangeinthegene'sreadingframe.Areadingframeisthesequenceofcodonsinthegenethatcorrespondtothespecificsequenceofaminoacids.Thus,frameshiftmutationsmayalterallofthecodonsthatoccurafterthedeletionorinsertion.Theresultingproteinisusuallynonfunctional.

https://ghr.nlm.nih.gov/primer/mutationsanddisorders/possiblemutations

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3. CentralDogmaofMolecularBiology(5thgradeonly)

a) TheDNAwithinagenecontainstheinformationonhowtojoinspecificaminoacidstogethertoformaprotein.TheinformationcontainedintheDNAisdeliveredtotheproteinmakingmachinery(ribosomes)throughanintermediatemessengercalledribonucleicacid(RNA).RNAandDNAaresimilarmolecules.

b) RNA-ThereareacoupleofkeydifferencesbetweenDNAandRNAmolecules.Theycontaindifferentsugars.DNAhasadeoxyribosesugarwhileRNAhasaribosesugar.Whilethreeoftheirfournitrogenousbasesarethesame,RNAmoleculeshaveabasecalleduracil(U)insteadofathyminebase.Uracilreplacesthepositionofthymineandformscomplementarypairswithadenine.DNAisadoublestrandedmoleculewhileRNAispredominatelyasinglestrandedmolecule.Finally,DNAisfoundinthenucleusofacell(alsointhemitochondriabuttheydon’tneedtoknowthat)whileRNAcanbefoundinthenucleus,cytoplasmandribosomes.

https://www.diffen.com/difference/DNA_vs_RNA

c) TranscriptionistheprocesswheretheinformationstoredasDNAinageneistransferredintoRNA.ThisRNAmoleculecanthencarrythisinformationoutofthenucleusandintothecytoplasm.Inthecytoplasm,ribosomescombinewiththeRNAmoleculeinordertoconvertthisinformationintoaprotein.Thisprocessisknownastranslation.Duringtranslation,geneticinformationisreadascodonstoassembleaminoacidsinaspecificsequencetoformaprotein.

ThereareseveraltypesofRNAmolecules.TheRNAgeneratedduringtranscriptionis messengerRNAormRNA.TeamsdonotneedtoknowthedifferencesbetweenRNA types.

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Onlytheterms“codingstrand”and“templatestrand”willbeusedintheevent.5thgrade teamsshouldunderstand:theDNAtemplatestrandisusedtogeneratetheRNAmolecule. https://basicbiology.net/micro/genetics/transcription-and-translation/ https://www.atdbio.com/content/14/Transcription-Translation-and-Replication

4. Chromosomes–AlloftheDNAinthenucleusofacellistightlypackagedintostructurescalledchromosomes.Humanshave23differentchromosomespairs.Mosthumancellshaveatotalof46chromosomesbecausetheyhavetwocopiesofeachchromosome,onefromtheirmotherandonefromtheirfather.Thesetwoversionsofthesamechromosomearecalledhomologouschromosomes.Twenty-twoofthechromosomesarecalledautosomesandarenumbered1to22.The23rdpairofchromosomesrepresentsthesexchromosomes,XorY.Ifyouareafemale,youwillhavetwoXchromosomes.Ifyouareamale,youwillhaveoneXandoneYchromosome.

3’…TACCGGACCTGAACT…5’

5’…ATGGCCTGGACTTCA…3’DNA

CodingStrand(alsoknowas:senseortopstrand)

TemplateStrand(alsoknowas:antisenseorbottomstrand)

5’…AUGGCCUGGACUUCA…3’RNA

Methionine–Alanine–Tryptophan–Threonine–Serine-….Protein

Transcription

Translation

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http://kidshealth.org/en/kids/what-is-gene.html http://kidshealth.org/en/parents/about-genetics.html

5. ChromosomeMorphologyandIdentification–Chromosomesdifferinsize,centromereposition,armlengthandstainingpattern.Inordertoidentifyindividualchromosomes,somecellsarecollectedandallowedtodividesothattheycanbeanalyzedatacertainpointduringmitosis.Thechromosomesarestainedwithspecialchemicalsandviewedunderamicroscope.Everychromosomehasacentromere(thepointwherethemitoticspindleattaches)andthechromosomestrandextendingfromthecentromereisreferredtoasanarm.Theshortarmislabeledp(forpetite)andthelongarmislabeledq(becauseqfollowspinthealphabet).Ifthecentromereisinthecenterofthechromosome,itiscalledmetacentric.Ifthecentromereislocatednearoneendofthechromosomeitiscalledacrocentric.Thethirdcentromerepositionmaybebetweenthecenterandtheendofthechromosomeandiscalledsubmetacentric.Chromosomescanalsobeidentifiedbytheiruniquebandingpatternwhentheyarestained.ThemostcommonstainisGiemsastain,whichresultsinwhatiscalledaGbandingpattern.Finally,chromosomescanalsobedistinguishedbytheiroverallsize.

Humanchromosomesstained withGiemsa(Gbanding)

6. KaryotypeAnalysis–Doctorsandgeneticistscanevaluatethenumberandconditionofanindividual’schromosomesbyassessingtheirkaryotype.Akaryotypeisthenumber,sizeandshapeofanindividual’schromosomes.Anindividual’skaryotypeisoftendisplayedasakaryogramwhichisaphotographoftheindividual’sstainedchromosomesarrangedintopairsfrom1to22followedbythesexchromosomes,XandY.Individualchromosomesareidentifiedbycomparingtheirsize,shapeandbandingpatterntoideograms,whicharediagrammaticrepresentationofthestainedchromosomes.Karyotypeanalysisisdonetoidentifygrosschromosomeabnormalitieslikemissingchromosomes,extrachromosomesorbrokenchromosomes.

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Karyograms

a) Monosomy–Monosomyisthetermforamissingchromosome.Anormalhumanshouldhavetwoofeveryautosomeandapairofsexchromosomes(XXorXY).Sometimesduringmeiosis(seebelow),amistakeismadeandonechromosomegetsleftbehind.Thehumanthatdevelopsfromthiseggorspermwouldbemissingoneofthepair.Mostfullchromosomemonosomyabnormalitiesarelethalinhumans.TheexceptionisTurnerssyndromeor45,Xwhichisnotlethal.AfemalewithTurnerssyndromemayhaveseveralphysicalabnormalitiesandisunabletoreproduce.

b) Trisomy–Trisomyisthetermforhavinganextrachromosome.Again,natureisnotperfectandsometimesaneggorspermisproducedwithanextrachromosome.ThemostcommonformofthistypeofgeneticdefectisTrisomy21orDownsyndrome.IndividualswithDownsyndromecanhaveavarietyofhealthconditions,intellectualdisabilitiesandcharacteristicfacialfeatures.

Teamsdonotneedtounderstandanyofthemolecularmechanismsthatresultinchromosomalabnormalities(nondisjunction).SomekaryotypesshowchromosomesthatlooklikeX’s.ThisoccurswhenthechromosomesareisolatedafterDNAreplicationbutbeforetheindividualchromatidshaveseparated.Iwillonlyusesinglechromatidkaryotypesliketheoneshownabove.Teamsshouldfocusonunderstandingwhatanormalhumankaryotypeshouldlooklikeandidentifyingdifferencesbetweenanormalhumankaryotypeandanabnormalone.Ifshownakaryotypethatismissingachromosome#2,theyshouldbeabletosayitisabnormalandthedefectismonosomy2.

c) Karyotypeanalysis(AppendixCandMagneticChromosomeKit)–Studentsmaybeaskedtolookatakaryogramandanswersomebasicquestionsaboutit.

http://www.slideshare.net/saimamansoorbugvi/karyotypes-and-karyotyping-15649528

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C. Celldivision

1. Mitosis–Asyougrow,yourcellsdivideandmakemorecells,makingyoubiggerandbigger.Asyouage,yourcellsalsodividetoreplaceoldcellswithneweronesortoreplacedamagedcells.Theprocessofonecelldividingintotwonewidenticalcellsiscalledmitosis.Priortothestartofmitosis,allthechromosomesinacellareduplicated.Duringmitosisthesechromosomesendupinthetwonewcellsthatareproduced.Theoriginalcell(ifhuman)willhaveatotalof46(remember,23differentonesbutoneeachfromthemotherandfather).Aftermitosis,youwillhavetwonewcells(“daughtercells”)eachwithidenticalcopiesoftheoriginal46chromosomes.

2. Meiosis–Theprocessofmeiosisincludestwocelldivisionsinwhichyoustartwithonecellwith46chromosomes(ifhuman)andendupwith4cellswith23chromosomes.Meiosisisusedtocreatesexcells(gametes,spermoregg).ThesecellshaveonlyIcopyofeachofthe23chromosomes.Whentheyarejoinedtogetherduringfertilizationtheresultingcellwillhave46chromosomes,23chromosomesfromthemotherand23chromosomesfromthefather.

Teamsdonotneedtoknowthestepsinvolvedintheprocessofmitosisormeiosis (prophase,anaphase,etc.).Theydonotneedtounderstandtheconceptofcrossing overinmeiosis. http://www.ducksters.com/science/biology/cell_division.php http://www.biology4kids.com/files/cell2_mitosis.html https://www.youtube.com/watch?v=f-ldPgEfAHI&t=310s https://www.youtube.com/watch?v=toWK0fIyFlY

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II. ClassicalGenetics–TeamsshouldonlyfocusonthefollowingbasicconceptsofclassicalorMendeliangenetics

A. TraitsandHeredity

1. Traitsarephysicalcharacteristicssuchaseyecolor,heightortheabilitytodance.Sometraitscanbeinfluencedbyanindividual’sbehaviororenvironment.Forexample,ifyouspendalotoftimeinthesun,thenyourskincolormaybecomedarkeroryoucanbecomeadancerbytrainingandpractice.Othertraitsareconsideredinheritedorgenetictraitsandaredeterminedbythegenesyouinheritfromyourparents.Forexample,youhaveblueeyesfromyourparentsorredhairfromyourgrandparents.

2. Heredityisthepassingoftraitsorphysicalcharacteristicsfromonegenerationtothenext(parentstochildren).

Teamsshouldunderstandthedifferencebetweenatraitthatisinheritedandonethatcan beinfluencedbytheenvironment.

B. Genes,Alleles,PhenotypesandGenotypes

1. AgeneisaparticularsequenceofDNAthathastheinstructionsforaparticularprotein.Thereareusuallyseveraldifferentversionsor“alleles”foragene.Forexample,thereisageneforeyecolorbutyoucanfindseveralallelesfortheeyecolorgenesuchasblueorbrown.(note-thegeneticsofeyecolorismuchmorecomplicatedbutwewanttokeepthingssimplehere).

2. Ingenetics,werefertothephysicalappearanceormake–upofanorganismasthephenotype.Whatyoulooklikeorwhetherornotyouhaveaparticularconditionwouldbeyourphenotype.

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3. Anindividual’sgenotypereferstotheirgeneticmake-up.Specifically,itisthetwoallelesthatyouinheritedfromyourparents.

a) homozygous–anindividualissaidtohaveahomozygousgenotypeifthetwoallelestheycarryarethesame

b) heterozygous–anindividualissaidtohaveaheterozygousgenotypeifthetwoallelestheycarryaredifferent

C. Dominantvs.Recessive

1. Ifwejustfocusonsimplepatternsofinheritance,thenwecanrefertodifferentversionsofallelesasbeingdominantorrecessive.

a) Adominantallelewilldetermineanindividual’sphenotyperegardlessofwhetherthatindividualishomozygousorheterozygousforthatallele

b) Arecessiveallelewillonlybeexpressedinthephenotypeofanindividualifthatindividualishomozygousforthatallele.Ifanindividualisheterozygous,withonedominantandonerecessiveallele,thedominantallelewinsandthatisthetraitthatyouwillseeinthephenotype.

c) Nomenclature–Forthepurposesofthisevent,geneswillbedenotedbythefirstletterofthedominantalleleforthattrait.Forexample,thealleleforaflowerwhosedominantcoloriswhitewouldberepresentedby“w”.ThedominantallelewouldberepresentedbyacapitalWandtherecessiveallelewithalowercasew.Aflowerthatishomozygousrecessivewouldhavethegenotypewwbutcouldbered.

2. PleaseseeappendixDforanexampleofhowthesegenetictermsworktogether.

D. PunnettSquares

1. Oneofthebenefitsofstudyinggeneticsisthatitallowsustopredictthelikelihoodofinheritingparticulartraits.Thisisveryhelpfulforplantandanimalbreedersandcanevenbeusedinhumanstohelpdeterminethechancesofhavingachildwithaparticulargeneticcondition.ThesimplestwaytodothisisbysettingupaPunnettsquare.APunnettsquareisagraphicalwaytosetupahypotheticalcrossorbreedingbetweentwoparentsanddetermineallthepossiblegeneticcombinationsorgenotypesoftheoffspring.

2. PleaseseeappendixEforaguidetosettingupandinterpretingPunnettsquares.Onlymonohybrid(singletrait)crosseswillbeused.Teamswillbeexpectedtosetupcrossesbasedontheinformationgivenaboutaparticulartraitandtheparentsandinterprettheresults.

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E. PedigreeCharts,AnalysisandPatternsofInheritance

1. Wecanbetterunderstandtheinheritancepatternofageneticdiseasewithinafamilybydoingapedigreeanalysis.Thisinvolvescollectinginformationaboutaparticulardiseasefromasmanyrelativeswithinafamilyaspossibleandconstructinga“familytree”orpedigreechart.Apedigreechartusessymbolsandlinestorepresentpeopleandrelationshipsandmakesiteasiertovisualizetherelationshipswithinfamilies.Withthisinformation,geneticistscanidentifytheinheritancepatternofaparticularconditionanddeterminetheriskofafamilymemberinheritingit.

2. AutosomalDominantandAutosomalRecessive

Bothgradesmustunderstandautosomaldominantandautosomalrecessiveinheritancepatterns.Atraitwillhaveanautosomaldominantinheritancepatternwhenonlyonecopyofitisnecessaryfortheindividualtohavethephenotypeassociatedwiththattrait.Atraitwillhaveanautosomalrecessiveinheritancepatterniftwocopiesarenecessaryforanindividualtohavethephenotype.

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3. Xlinkedrecessive(5thgradeonly) ForatraittohaveanXlinkedrecessiveinheritancepatternthegeneforthetraitmustfirstbe locatedontheXchromosome.SincefemaleshavetwoXchromosomes,anXlinkedrecessive traitwillonlybepresentinfemaleswhentheyhavetwoallelesforthattrait.However,males onlyhaveoneXchromosomesotheywillhavethephenotypeforthistraitwithonlyonecopy ofthatallele.MalesareaffectedbyX-linkedrecessivedisordersmuchmorefrequentlythan females.AcharacteristicofX-linkedinheritanceisthatfatherscannotpassX-linkedtraitsto theirsons(nomale-to-maletransmission).

4. PleaseseeappendixFforaguidetosettingupandinterpretingpedigreecharts.Teamswillbeaskedtoidentifyandunderstandthecomponentsofthepedigreechartaswellasidentifytheinheritancepatternforthetrait.

https://www.brainpop.com/health/geneticsgrowthanddevelopment/heredity/ http://anthro.palomar.edu/mendel/mendel_2.htm http://www.dnaftb.org http://www.sciencebuddies.org/science-fair-projects/project_ideas/Genom_p010.shtml-background

F. HumanABOBloodTypes–ExampleofCo-dominanceandMultipleAlleles

1. Wehavetalkedaboutallelesbeingdominantorrecessivetoeachother.Thisisnotalwaysthecase.Manytimestherearemultiplealleleoptionsforaparticulargenealthoughyouwillneverinheritmorethantwo.Inaddition,therearetimeswhenbothofthetwoallelesyouinheritareexpressedtogetherresultinginaphenotypethatisacombinationofthetwo.Thisisreferredtoasco-dominant.ThehumanABObloodtypegroupsareanexampleofco-dominanceandmultiplealleles.

2. Humansareassignedtoabloodgroupbasedonthepresenceorabsenceofspecificantigensor“markers”ontheirredbloodcells.Therearethreepossiblealleles,A,BorO.BothAandBallelesaredominantoverO.Asaresult,individualswhohaveanAOgenotypewillhaveanAphenotype.PeoplewhoaretypeOhaveOOgenotypes.Inotherwords,theyinheritedarecessiveOallelefrombothparents.TheAandBallelesareco-dominant.Therefore,ifanAisinheritedfromoneparentandaBfromtheother,thephenotypewillbeAB.

3. AppendixGshowsadetaileddescriptionofthehumanbloodgroupgenotypesandphenotypes.

http://anthro.palomar.edu/blood/ABO_system.htm Note:Someofthecrossesandpedigreestheteamswillbegivenmaybehypotheticalor simplifiedinordertopreventanyconfusionandtofocusonthebasicconceptsofinheritance patterns.

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III. HumanGeneticDiseasesandConditions

A. Pleasebesensitivewhendiscussinggeneticdiseasesandconditionswithyourteams.Itispossiblethatstudentswillhavefamilymembers,friendsorclassmateswithoneoftheseconditions.Itwouldbebeneficialtoexplaintoyourstudentsthatmanyfamiliescarrygeneticlinkstodifferentdiseases.Thereisagreatdealofresearchbeingdoneonthetreatmentanddetectionofgeneticdiseases.Manyconditionscanbetreatedand/ormanagedandindividualswiththeseconditionscanlivehappyproductivelives.

B. Pleaseconsultthechartbelowforinformationonthe6listedgeneticconditions.Frequenciesareapproximateandoftengivenforspecificgroups.Teamswillnotbeexpectedtoprovideanyofthisdetailedinformationbutshouldbeabletoidentifythegeneticconditionifgiventhespecificdetailsofthedisease.

GeneticCondition Descriptionof

Disease/ConditionFrequencyintheSpecificUSPopulation

GeneticDefect(mostcommon)/PatternofInheritance

CysticFibrosis Thebodyproducesstickymucusthatresultsinrespiratoryanddigestiveproblems

1/2500CaucasianAmericans

MutationsintheCFTRgene(autosomalrecessive)

SickleCellDisease Redbloodcellsbecomestiff,pileup,andcauseblockagesinsmallbloodvesselsandorgans

1/500AfricanAmericans Mutationinthehemoglobin-Betagene(autosomalrecessive)

Huntington’sdisease Progressivebraindisorderthatcausesuncontrolledmovements,emotionalproblemsandlossofthinkingability

1/10,000Americans Mutationinthehuntingtingene(autosomaldominant)

DownSyndrome Intellectualdisability,characteristicfacialappearanceandavarietyofbirthdefects

1/800births Trisomy21/errorinmeiosis

TurnersSyndrome Thesefemalesareusuallyshortinstature,mayhavewebbedneckandareinfertile

1/2,500females MonosomyX/errorinmeiosis

HemophiliaA(5thgradeonly)

Bleedingdisorderthataffectsthebloodsabilitytoclot

1/5000males MutationintheFactorVIIIgene(Xlinkedrecessive)

https://www.genome.gov/10001204/http://positivemed.com/2014/03/24/10-common-genetic-disorders/https://ghr.nlm.nih.gov/condition

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GlossaryofTermsDNA(deoxyribonucleicacid)Themoleculethatcarriesthegeneticinstructionsfoundinhumancellsandmostotherformsoflifeonearth.RNA(ribonucleicacid)Themoleculethatisgeneratedduringtranscriptionandplaysanessentialroleinproteinsynthesis.ThestructureissimilartoDNA.NucleotideThebuildingblockofDNAandRNA.Itiscomprisedofaphosphate,asugarandabase;adenine(A),thymine(T),cytosine(C)orguanine(G).InRNA,uracil(U)isusedinsteadofthymine.MutationAchangeintheDNAsequencethatmakesupagene,suchthatthesequencediffersfromwhatiscommonlyfound.Mutationscanbegood,badorjustdifferentversionsofthatgene.CodonAsequenceofthreenucleotidesinagenethatcorrespondstoaspecificaminoacidorastopsignalduringproteinproduction.CodonsprovidethecodethatallowsaDNAsequencetobetranslatedintoaproteinsequence.TranscriptionThetransferofaDNAsequenceintoRNA.TranslationTheprocessinwhichthegeneticcodecarriedbyRNAdirectsthesynthesisofproteinsfromaminoacids.CodingStrandThe5’to3’sequenceofagenethatcontainsthegeneticcodefortheaminoacidsequenceofaprotein.TemplateStrandThe3’to5’sequenceofagenethatisusedduringtranscriptionasatemplateforRNAproduction.ChromosomeAtightlypackedindividualmoleculeofDNAlocatedinthenucleus.Humanshaveatotalof46chromosomes,23pairs.HomologousChromosomesThetwochromosomepairofanyindividualchromosometype.Oneisinheritedfromthemother,andonefromthefather.CentromereAspecializedchromosomeregiontowhichspindlefibersattachduringcelldivision.GBandingAtechniquewhereGiemsastainisusedtocreateaspecificbandingpatternoneachchromosomesothattheycanbeidentifiedandanalyzedforabnormalities.AcrocentricAchromosomewiththecentromerelocatednearoneend.MetacentricAchromosomewiththecentromerelocatedinthecenter.

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SubmetacentricAchromosomewiththecentromerelocatedbetweenthecenterandtheend.KaryotypeThenumber,sizeandshapeofanindividual’schromosomes.Anindividual’skaryotypeisoftendisplayedasakaryogram,whichisaphotographoftheindividual’sstainedchromosomesKaryogramTheactualdisplayofasetofchromosomes.MonosomyWhenanindividualismissingachromosome.TrisomyWhenanindividualhasanextrachromosome.MitosisWhenonecelldividesinto2geneticallyidenticaldaughtercells.MeiosisTworoundsofcelldivisionresultingin4cellswithhalfthenumberofchromosomesoftheoriginalstartingcell.TraitPhysicalorbehavioralcharacteristics.Traitscanbeinheritedoracquired.HeredityThepassingoftraitsfromparentstooffspringthroughtheinheritanceofgenes.GeneThesegmentofDNAthatcontainsthespecificinstructionsformakingaprotein.AlleleDifferentversionofagene,DNAsequencewilldiffer.HomozygousHavingthesametwoversionsofanallele.HeterozygousHavingdifferentversionsofanallele.DominantThealleleforatraitthatwilldetermineanindividual’sphenotypewhentheyareheterozygous.Theallelethatisexpressed.RecessiveThealleleforatraitthathasnoeffectonphenotypewhenpresentinaheterozygousindividual.Itisonlyexpressedwhenyouhavetwocopiesofthisallele.X-LinkedRecessiveGenecarriedontheXchromosomethatisrecessiveinfemalesbutactsinadominatefashioninmalesbecauseonlyonecopyispresentPhenotypeAnorganism’sphysicalorexpressedtraits.Whattheylooklike.GenotypeTheallelesanorganismhas.Theirgeneticmake-up.PedigreeChartAdiagramusingsymbolsandlinestorepresentpeopleandrelationshipsmakingiteasiertovisualizetherelationshipswithinfamilies.Itrecordstheappearanceofaparticularphenotypeforagenewithinthefamily.PunnettSquareAgraphicalwaytosetupahypotheticalcrossorbreedingbetweentwoparentsanddetermineallthepossiblegeneticcombinationsorgenotypesoftheoffspring.

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AdditionalResourceshttps://www.soinc.org/heredity_bhttp://www.nclark.net/Geneticshttp://peer.tamu.edu/NSF_Files/Introduction%20to%20Genetics.ppthttp://knowgenetics.orghttp://www.sciencekidsathome.com/science_topics/genetics-a.htmlhttps://kidsbiology.com/biology-basics/the-science-of-genetics/

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AppendixA

IdentifywhatpartoftheDNAmoleculeeachletterrepresents. A ___________________________ B ___________________________ C ___________________________ D ___________________________ E ___________________________ F ___________________________ G ___________________________ H ___________________________ I ___________________________ adenine,cytosine,thymine,guanine,doublehelix,phosphate,deoxyribosesugar,5’ end,3’end

A

B

C D

E

F G

H

I

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AppendixB

GENE-iusDNACodonTable

(DNAnucleotidetripletstoaminoacids)2ndbase

1stbase T C A G 3rdbase

TTTT-Phenylalanine TCT-Serine TAT-Tyrosine TGT-Cysteine T

CAG

TTC-Phenylalanine TCC-Serine TAC-Tyrosine TGC-CysteineTTA-Leucine TCA-Serine TAA-Stop TGA-StopTTG-Leucine TCG-Serine TAG-Stop TGG-Tryptophan

C

CTT-Leucine CCT-Proline CAT-Histidine CGT-Arginine TCAG

CTC-Leucine CCC-Proline CAC-Histidine CGC-ArginineCTA-Leucine CCA-Proline CAA-Glutamine CGA-ArginineCTG-Leucine CCG-Proline CAG-Glutamine CGG-Arginine

A

ATT-Isoleucine ACT-Threonine AAT-Asparagine AGT-Serine TCAG

ATC-Isoleucine ACC-Threonine AAC-Asparagine AGC-SerineATA-Isoleucine ACA-Threonine AAA-Lysine AGA-ArginineATG–Methionine(start) ACG-Threonine AAG-Lysine AGG-Arginine

G

GTT-Valine GCT-Alanine GAT–AsparticAcid GGT-Glycine TCAG

GTC-Valine GCC-Alanine GAC–AsparticAcid GGC-GlycineGTA-Valine GCA-Alanine GAA–GlutamicAcid GGA-GlycineGTG-Valine GCG-Alanine GAG–GlutamicAcid GGG-Glycine

Genesequence:ATGGTTCACAGTTTCTCGGGCAAATAG Aminoacidsequenceofprotein:Methionine-Valine-Histidine-Serine- Phenylalanine-Serine-Glycine-Lysine-stop IfgivenaDNAsequencenotstartingwithATG,theyshouldbeabletofind thefirstATGandstartreadingthetripletcodonsfromthatpoint. Genesequence:GACTAATGGGATATCCAACTCTTCGTGTATGA Aminoacidsequenceofprotein:Methionine-Glycine-Tyrosine-Proline- Threonine-Leucine-Arginine-Valine-stop Note:Sequencesgivenduringtheeventwillnotbecolorcodedasabove.5thgradeteamsmustalso beabletogiveanaminoacidsequenceifgivenaRNAsequence.

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AppendixC

Isthisindividualamaleorfemale?Isthekaryotypenormal?Howmanychromosomesdoesthisindividualhave?Ifthekaryotypeisnotnormal,whatistheabnormality?

Updated:January2019

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AppendixD

Updated:January2019

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AppendixE

PunnettSquares

1. Firstyouneedtodeterminethegenotypeoftheparents.Sometimesthegenotypeisknownbasedonthephenotype(i.e.-iftheindividualexpressestherecessivetraitthentheyhavetobehomozygousforthatrecessiveallele).Otherwise,thegenotypeswillbespecificallygiven.

2. Nextyouneedtodrawasquarewith4boxeswithinit.3. Eachalleleforparent1isplacedontheleftsideofthesquareandeachalleleofparent

2isplacedonthetopasshown.(orderdoesnotmatter)4. Thepossiblegenotypesoftheoffspringarethendeterminedbycombiningtheallelesof

theparentsintothe4possibleoutcomes,oneineachbox.5. Usingthisinformationyoucandeterminethepercentageofoffspringyoushouldexpect

foreachgenotypeandresultingphenotype.6. Belowaretwosamplecrossesofmiceforthetraitofeyecolor.Blackeyesare

dominantoverredeyes.

ParentalGenotypes:

Parent1HomozygousDominant

blackeyesBB

Parent2HomozygousRecessive

redeyesbb

b b

B

B

These4squaresrepresentthe4possiblegenotypes.Eachoneis25%ofthetotaloffspring.

Bb

Bb Bb

Bb

PossibleGenotypesand%:Bb,100%PossiblePhenotypeand%:blackeyes,100%

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ParentalGenotypes:

Parent1Heterozygousblackeyes

Bb

Parent2HomozygousRecessive

redeyesbb

b b

B

b These4squaresrepresentthe4possiblegenotypes.Eachoneis25%ofthetotaloffspring.

bb

Bb Bb

bb

PossibleGenotypesand%:Bb,50%bb,50%PossiblePhenotypeand%:blackeyes,50%redeyes,50%

SampleQuestionInpeaplants,seedtexturecomesintwotypes,roundorwrinkled.Theroundseedallele(R)isdominantoverthewrinkledseedallele(r).Twopeaplantsthatareheterozygousforseedtexturearecrossed.Answerthefollowingquestions.

Whatisthegenotypeofthetwoplantsusedinthiscross?___________________Whatisthephenotypeoftheseplants(roundseedsorwrinkledseeds)?_________________FilloutthePunnettsquarebelow.

Belowarefourpossiblegenotypes.Whatpercentageofeachgenotypewouldyouexpecttoseeintheoffspringofthiscross?Genotypes: RR Rr rrPercentages:_______% _______% _________%

Belowarethetwopossiblephenotypesforseedtexture.Whatpercentageofeachphenotypewouldyouexpecttoseeintheoffspringofthiscross?Phenotypes: round wrinkledPercentages:_______% _______%

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AppendixFPedigreeCharts

AutosomalDominantorRecessiveInheritancePatternsTryingtoidentifyatraitasdominantorrecessivecanbealittletrickyespeciallywhencarriersarenotidentified.Theeasiestwaytodothisistoruleoutadominanttrait.Ifatraitisdominant,thentheaffectedindividualwillhaveinheritedthatallelefromaparentandwillhaveanaffectedparent.

Thepedigreeontheleftcouldstillbearecessivetraitwiththefatherbeinghomozygousrecessiveandthemotherbeingheterozygous(carrier).Inordertodeterminethat,moreinformationintheformofmorefamilymemberswouldbeneeded.Herearethebasicguidelines:DominantInheritance

• Traitshouldnotskipgenerations.• Anaffectedpersonmarriedtoa"normal"personshouldhaveapproximately50%oftheoffspring

beingaffected.(Alsoindicatesthattheaffectedindividualisheterozygous).RecessiveInheritance

• Traitoftenskipsgenerations.• Ifbothoftheparentsareaffected,allofthechildrenshouldbeaffected.• Mostaffectedindividualshave"normal"parents.

Squaresareusedtoindicatemales.

Circlesareusedtoindicatefemales.

Individualsthatare“affected”orhavethetraitthatyouarestudyingareshaded.

Sometimes,ashapewillbehalfshadedifthatindividualisaknownheterozygousor“carrier”ofthattrait.Note–mostofthetimecarriersarenotidentified.

Alinebetweenamaleandfemaleindicatesamarriage.Alinedrawndownfromamarriagelineindicateschildren.Eachrowofindividualsrepresentsageneration.

MightbedominantCan’tbedominant.Mustberecessive

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• Whena"normal"personismarriedtoanaffectedindividual,allofthechildrenarenormal(indicatingthenormalparentishomozygousdominant).

• Ifa"normal"personismarriedtoanaffectedindividualandoneormoreofthechildrenisaffected,thenapproximatelyhalfofthechildrenshouldbeaffected.(Showingthatthe"normal"parentisheterozygous).

XLinkedRecessiveInheritancePatterns(5thgradeonly)● Traitismuchmorefrequentinmales.● Thereisnofathertosontransmissionofthetrait.Ifthereis,itexcludesXlinkedinheritance.● Thediseasecanskipgenerationswithcarrierfemales.

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SampleQuestionExaminethepedigreechartbelowforaconditioncalledFalconianemia(Forf).Eachnumberinthechartreferstotheindividualaboveit.Answerthequestionsbelow.

1. Isindividual#1maleorfemale?

2. Whatistherelationshipbetweenindividuals#5and#6?

3. Whatistherelationshipbetweenindividuals#3,#4,and#5?

4. Whatistherelationshipbetweenindividuals#1and#3?

5. Howmanygenerationsarerepresentedinthischart?

6. Whichindividualsrepresentaffectedindividuals(thosewithFalconianemia)?

7. Whatisthegenotypeofindividual#2?

8. DoyouthinkFalconianemiaisanautosomaldominantorrecessivetrait?

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AppendixG

HumanABOBloodTypes

SampleQuestionIfamanwhoisbloodtypeABmarriesawomanwhoisbloodtypeO,whatarethepossiblebloodtypesoftheirchildren?