Post on 29-Apr-2018
INHERITANCETopic3-2017
Year10Biology
TOPIC3–INHERITANCE
Thingstocover:1. ReviewofTopics1-4
2. Genes&alleles
3. Heterozygous&homozygous
4. Genotypes&phenotypes
5. Dominanttraits&recessivetraits
6. Autosomal&sex-linkedtraits
7. Mutations
8. Pedigrees
Worktodo:
1. Activity–JerrySpringerpunnetsquares
2. Trollphenotypes
3. Punnetsquares–monohybridandsex-linked
4. TextbookQs–Ch2.6–Q-1-3,6,7,8,9,13
5. TextbookQs–Ch2.7–Q-2,3,5,6,7,8,9,
6. TextbookQs–Ch2.8–Q-1,3,4,6,7,8,10,11
7. TextbookQs–Ch2.9-Q-1-5,10,11,12,14
Ideastoknow:
• Gene
• Allele
• ABObloodgrouping
• Homologouschromosomes
• Gametes
• Heterozygous
• Homozygous
• Dominant
• Recessive
• Basesubstitutionmutation
• Frameshiftmutation
• Insertion
• Deletion
• Genotype
• Phenotype
• Completedominance
• Co-dominance
• Carrier
• Punnettsquare
• Monohybridcross
• Pedigreechart
• Genderbiasinpedigrees
• Generationskippinginpedigrees
• Sexlinkage
• Haemophilia
• Colourblindness
REVIEW
Topic1• DNAiscomposedof____________________.
• Eachnucleotideconsistsof:
− A____________________sugar
− A____________________group
− A____________________base(_____types)
• Thenucleotidesformchains.Twochainstwisttoformthe____________________shapeof
theDNAmolecule.
• ChemicalbondsholdtheDNAmoleculetogether.Strong____________________bondshold
thenucleotidestogether,whileweak____________________bondsformbetweenthe
bases.
Topic2
• DNAiscoileduptightlytoform_______________
• Thereare_______________ofchromosomesineverycell.
• Mostoftheseare_______________,controllinggeneralcharacteristics.
• Onepairarethe_______________,controllingbothsexualandgeneralcharacteristics.
• Celldivisionisnecessaryfor____________________,____________________and
reproduction.
• Onetypeofcelldivision,____________________,isusedintheformationofnewbodycells.
Itisalsousedbyunicellularorganismsfor____________________reproduction.The
__________daughtercellsformedare____________________totheparentcellandhave
__________chromosomes.
• Theothertypeofcelldivision,____________________,isusedtoformsexcells.Another
namefortheproductsofthistypeofdivisionare____________________Thisprocesstakes
placeinthereproductiveorgans.The__________daughtercellsformedare
____________________totheparentcellandhave__________chromosomes.Theyarealso
____________________insize.
• Inorderforcelldivisiontooccur,theDNAmust____________________andthe
REVIEW
chromosomesmustdivideequallybetweenthecells.
• ____________________canoccurifthisdoesnothappencorrectly.Forexample,disorders
involvingadditionalormissing____________________.
• DownSyndromeisoneexample.Thisdisorderresultsfromthepresenceof
____________________Chromosome21.Thisiscalled____________________21.
•
VARIATION
ThepopulationoftheEarthismorethan6billionpeople,andnotwoindividuals(apartfromidenticaltwins)aregeneticallythesame.Why?
• Peoplearedifferentbecausethey________________________________________
____________________(or____________________)fromtheirparents.
• Childrencarrya____________________setof____________________;halffromtheir
motherandhalffromtheirfather.
• Aperson’suniquecharacteristicsarecausedby:
− the________________________________________theyinheritedfromtheir
parents(____________________)
− the________________________________________inwhichtheydeveloped
(____________________)
• Somecharacteristics,suchas____________________colourand____________________
shape,areonlydeterminedbygenes.Thesearecalled____________________
characteristics.
• Othertypesofcharacteristics,suchas____________________andhairlength,arenot
inheritedbutdependon________________________________________.Thesearecalled
____________________characteristics.
• Differencesinsomecharacteristicsareduetoa____________________ofbothinherited
andenvironmentalfactors.Insomecases,itcanbedifficulttosayhowmuchinfluenceeach
factorhas.
• Theoverallappearanceofanorganismdependson:
1. its____________________(inheritedcharacteristics)2. theeffectsofthe____________________inwhichitlives.
• Alltheobservablecharacteristicsofanorganismarecalledits____________________.
• Thefullsetofgenesofanorganismiscalledits____________________.
• Anorganism’sphenotypethereforedependsonits____________________plus________________________________________.
VARIATION
• ________________________________________isthemostimportantcauseof
________________________________________becauseitmixesupgeneticmaterial.
• During____________________,homologouschromosomes____________________
geneticmaterial.Theythenlineupandseparateindifferentways,
producingalarge____________________ofdifferent
____________________.
• At____________________,anymalegametecancombine
withanyfemalegamete.
• Alltheseeventsoccur____________________andcreate
new____________________ofgeneticmaterial.
• ____________________isthe____________________inthe____________________or____________________of____________________andisthereforeanothercauseofgeneticvariation.
• Mutationscanarise____________________;forexample,throughtheincorrectcopyingof
basepairsduringDNAreplication,orthe____________________distributionof
chromosomesduring________________________________________.
• Mutationscanalsobecausedby________________________________________,suchas
radiationandcertainchemicals.Thesefactorsarecalled____________________.
• Somemutationsmaybebeneficial,butmanyareharmfulandincreasetheriskofdiseases
suchas____________________.
GENES&ALLELES
• Thebasic____________________of____________________isthe____________________.• Ageneisasegmentofa____________________thatcontainsthe____________________
requiredtoproducea____________________.
• Thereare____________________ofeachchromosome,knownasa
________________________________________.Eachcopyhasitsown
____________________ofthegene.
• Theseversionsareknownas____________________.
• Mostgenesarecontrolledby____________________.
• Dominantalleles:− ____________________expressedinacell’s____________________
− only____________________ofthedominantalleleneedstobeinheritedinorderfor
ittobeexpressed
− representedbyan____________________caseletter(eg._______)
• Recessivealleles:− onlyexpressedinacell’sphenotypeif____________________arepresent
− ifonlyonecopyispresent,itseffectis‘____________________bythe
________________________________________
− representedbya____________________caseletter(eg._______)
• Iftheallelesforacharacteristicinahomologouspairarethe____________________,the
organismissaidtobe____________________forthatcharacteristic.
• Ifthereare____________________alleles,theorganismissaidtobe
________________________________________
forthatgene.
• Ifthereare____________________alleles,theorganismissaidtobe
________________________________________
forthatgene.
GENES&ALLELES
• Iftheallelesforacharacteristicinahomologouspair
are____________________,theorganismissaidto
be____________________forthatcharacteristic.
• Thecharacteristic____________________byheterozygousalleleswilldependonwhich
alleleis____________________andwhichalleleis____________________.
• Thealleleforbrowneyesis____________________overthealleleforblueeyes.• Theindividualwillhave____________________eyes,becausethealleleforbrowneyes
____________________thealleleforblueeyes.
TYPESOFINHERITANCE
COMPLETEDOMINANCE:ßNORMAL!!!!!• Ifthe____________________alleleispresent,itwillbe____________________
• eg.Browneyedallele(B)alwaysexpressedwhenpresent(BBorBb)
• Specialsymbols:
− Choose____________________
− Use____________________(recessive)and____________________(dominant)− eg.BB,bborBbß_______________________________________________________
CO-DOMINANCE:• Thereis________________________________________!
• Thephenotypeisa____________________ofbothallelespresent
• eg.redallele+whiteallele=____________________phenotype
• eg.____________________bloodfromcombinationofAandBalleles
• Specialsymbols:
− Choose____________________
− Use____________________forboth
− eg.RR,WWorRWß_____________________________________________________
ABOBLOODGROUPING
• Todetermineyourbloodtype,therearethreealleles:− A–____________________
− B-____________________
− O-____________________
• TheallelesIAandIBare____________________• However,bothoftheseallelesare________________________________________overί• Thisresultsin____________________differentphenotypes.
Phenotypeorbloodgroup
Genotypes
TypeA
TypeB
TypeAB
TypeO
TYPESOFINHERITANCE
AUTOSOMALINHERITANCE:ßNORMAL!!!!!• Thegeneinquestionislocatedonan____________________
• Traitscanbe:
− ________________________________________–meaningthatatrait/disorderis
determinedbythepresenceofadominantallele
− ________________________________________–determinedbythepresenceof
tworecessivealleles
• Specialsymbols:
− BB,bb,Bb
SEX-LINKEDINHERITANCE:• Thegeneinquestionislocatedona________________________________________
• Willgenerallybeonthe____________________,astheYcarriesveryfewgenes
• eg.____________________,________________________________________
• Traitscanbe:
− ________________________________________–meaningthatatrait/disorderis
determinedbythepresenceofthedominantalleleontheXchromosomes
− ________________________________________–meaningthatatrait/disorderis
determinedbythepresenceofoneortworecessiveallelesontheXchromosomes
• Specialsymbols:
− Females:
• Homozygous____________________ • Heterozygous__________
− Males(onlyoneXchromosome):
• Unaffected __________
• Affected __________
CARRIERS:• Someonewhois____________________foragenetic
disorder
• They____________________thedisorderthemselves
• However,thedisordercanbe____________________
tothenextgeneration
GENETICMUTATIONS
• Genesarenearlyalwayspassedfromparenttooffspring_____________________________.
• Occasionallya_________________willoccurinagene.
• Thisiscalleda__________________________________.
• __________________________________:
– onebaseis_________________foranother
• __________________________________:
– _________________
• insertionofoneormorebases
– _________________
• deletionofoneormorebases
• • Why?
– MutationinvolvesapartoftheDNAwhichthatparticularcell____________________
– Mutationoccursbutthecode
stillresultsinthesame__________________________________&thereforethesame_________________
• Generally,_________________mutationsaremoreserious.
PUNNETTSQUARES
• Alsocalled_________________ _________________
• Methodusedtofindthe_________________ genotypeandphenotyperatiosof_________________ whentheparentalgenotypesand/orphenotypesareknown.
• Steps:1. Writedownthe_________________ _________________
Youmayneedtochooselettertorepresentyourtrait
–chooseeasyoneslikeT,G,HnotC,S,Y
2. Writedownthe_________________ _________________ thattheyareabletopasson
intheirgametes(sexcells)3. ConstructthePunnettsquare
4. Fillinthe_________________ _________________ oftheoffspring
5. Determinethe_________________ _________________ oftheoffspring
6. Determinethe_________________ _________________ oftheoffspring
PUNNETTSQUARES
• Example:
Analienthatishomozygousdominantforgreenskinhaschosenanalienwhohaspurpleskinforhisbride.Determinethelikelihoodthattheirchildrenwillhavepurpleskin.
LikeinMaths–youneedtostatewhatsymbolsyouwillbeusingtorepresentyourtraits:
eg.LetG=green;g=purple
• Example:Oneofthecouplessons(Neyp)marriedafemalealienwhowashomozygousrecessiveforthe
skincolourtrait.
Workoutthegenotypeandphenotypepercentageoftheirpotentialoffspring.
PUNNETTSQUARES
• Example:
OneofNeyp’ssonsmarriedafemalealienwhowashomozygousforhaemophilia.
Calculatethelikelihoodthattheycouldhaveachildwithhaemophilia.
Again–specifyyoursymbols!
Itisasex-linkedrecessivedisorder!!!
So:LetH=_________________;h=_________________
PEDIGREECHARTS
• Showsthemembersofafamilyandhowtheyare_________________ toeachother.
• A___________________________________________________!
• Pedigreechartscanalsobeusedto_________________ the_________________ ofa_________________.
• Circles=_________________
• Squares=_________________
• Shading=_________________ individuals
• Parents=linkedbya_________________ line
• Children=_________________ linesrunningdownfromparents
• Siblings=linkedbya_________________ line_________________ them
PEDIGREECHARTS
• Example:DrawapedigreechartforNeypandhiswifeGjup.,includingtheirparentsandchildren.They
had3children,2boysandagirl.TheirdaughterHefghadpurpleskinandmarriedanalien
whoalsohadpurpleskin.Theyhadoneson–Yerg.TheirsonGuolhadgreenskinandwas
alsomarriedwithonepurpledaughter,Zcug.
Remember,beingpurpleistherecessivetrait!
• Pedigreechartscanalsobeusedtodetermineif:
– Thecharacteristicis_________________ or_________________.
– Thecharacteristicis_________________ or_________________.
• Thingstolookfor:
– Genderbiasofmales:females
– Affectedoffspringfromunaffectedparents
– Affectedsonsfromaffectedfathers
PEDIGREE–AFAMILYTREEMakeyourownfamilytreeforonetraitofyourchoosing(eyecolour,naturalhaircolour,orbloodtype).
Includeasmanypeopleonyourimmediatefamilyaspossibleandusealloftherulesforpedigrees.Identify
thenamesandgenotypesofallindividualsinyourpedigree.
AttachanswerstotextbookQstothebackofthebooklet