final gene-ius study guide · 2020-01-20 · updated: january 2019 1 gene-ius study guide this...

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Updated: January 2019 1 GENE-ius Study Guide This study guide is intended to help GENE-ius coaches understand the topics the event will cover and the level of comprehension expected for those topics. It is recommended and expected that additional materials, websites and activities be used to help prepare the teams for this event. I. Basic Cell/Molecular Biology – Students should only focus on the following basic concepts of eukaryotic (will stick to animal) cells. A. Parts of the cell 1. What is a cell? – A cell is the basic unit of life. All living things are made up of one cell (like bacteria or yeast) or many cells (like humans). Each cell is like a mini factory with individual parts (organelles) working together to carry out specific functions. 2. Cell membrane – The cell membrane is the outermost layer of the cell. It is like a bag that holds everything together. It contains openings that allow things to enter and leave the cell. It is like the shipping and receiving department in the cell factory. 3. Cytoplasm – The cytoplasm is a liquid substance that fills up the space inside the membrane. It holds all the other organelles of the cell in place and helps give the cell shape. It is like the busy factory floor with things moving about. 4. Nucleus – The nucleus is the “brains” of the cell. It is the control office. It houses the genetic material of the cell (DNA/genes/chromosomes). It has its own membrane, the nuclear membrane. 5. Ribosomes - The “workers” of the cell factory. Ribosomes use the instructions stored in DNA to assemble proteins. Proteins are the building blocks and machines the cell uses to carry out its many functions. RIBOSOME

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Page 1: Final GENE-ius Study Guide · 2020-01-20 · Updated: January 2019 1 GENE-ius Study Guide This study guide is intended to help GENE-ius coaches understand the topics the event will

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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?

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AppendixD

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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?