Apple Genetics
Name _________________________
Part 1: Comparing Royal Gala and Braeburn Apples
RoyalGalaApple
BraeburnApple
Explainwhatyouobserveontheoutsideandinsideofthisparticularapple.
Writedownwhatyounotice,stemstructure,seedlayout,andcoloring.
Look
OutsideofApple
InsideofApple
Smell
OutsideofApple
InsideOfApple
Redwithgreenspeckles,someyellow Redwithgreenspeckles,someyellow
togreenareas,shorterandfatter
togreenareas,tallerandskinnier
Whitecolor
Whitecolor
Explainwhatyouobserveusingyoursenseofsmell.
Littletonosmell,smellslikeapple
Littletonosmell,smellslikeapple
Smellsalittlelikeapumpkin
Nothingdistinctive
Explainwhatyouobserveaboutthetextureoftheapple.i.e.skin,meat,seed,
stem
Touch
OutsideofApple
(Texture)
InsideofApple
(Numberof
seedsandseed
shape)
Taste
Tartness
Sweetness
Juiciness
Crunchiness
Waxyandsmooth
Waxyandsmooth
Answersmayvary(6-10seedsis
common),teardropshape
Answersmayvary(6-10seedsis
common),teardropshape
Explainwhatyouobservewhenyoutasteyourapple.
Lesstart
Moretart
Moresweet
LessSweet
Lessjuicy
Veryjuicy
Verycrunchy
Verycrunchy
1
Apple Genetics
(continued)
Part 2: Analyzing the Data:
1. ExplainwhatsimilaritiesyoufoundintheRoyalGalaandBraeburnapples?
Bothhadsimilarexteriorsvisually,smell.Bothwerejuicy,crunchyapplesgoodforeating.
2. ExplainwhatdifferencesyoufoundinRoyalGalaandBraeburnapples?
Galawassweeterandlesstart,lessjuicy,andsmelledalittlelikepumpkinwhiletheBraeburnwas
moretart,lesssweet,didn’tsmelllikemuchofanything,andwasVERYjuicyandcrunchy.
Part 3: Completing Punnett Squares
WhenmakingobservationsinPart1,youdescribedtraitsforeachapplesuchascolor,juiciness,or
sweetness.Thesetraitsaredeterminedbythegenesintheapple.Ifweweretocrossbreed
blossomsonaRoyalGalaappletreewithpollenfromaBraeburnappletree,theresultingfruit
wouldlook,smell,taste,andfeellikeaRoyalGalaapple,buttheseedsinsidewouldpossessgenes
frombothoftheseparents.Theseedscouldbeplantedandgrownintoanewhybridwithfruitthat
hastraitsofboththeRoyalGalaandBraeburnapple.
Inthisactivity,wewillimaginethatthetraitsyouobservedaredeterminedbyMendelian
inheritanceinwhichasinglegenedeterminesatrait.Eachtraitisdominantorrecessiveandthe
allelespasseddownfromtheparentsdeterminewhetherthetraitwillbeobservedintheoffspring.
BelowareexamplesofgenotypesthattheGalaandBraeburnapplesmaypossess.NOTE:These
genotypesaretobeusedasexamplesonlyanddonotrepresentaccurategenotypes.Youwill
usethisinformationtocompletePunnettSquaresonthefollowingpageandcalculateprobabilities
foreachgenotype.
a.
b.
c.
d.
e.
f.
Tartnessisrecessive(Gala’sgenotypeisTT,Braeburn’sgenotypeistt)
Sweetnessisrecessive(Gala’sgenotypeisss,Braeburn’sgenotypeisSS)
Juicinessisdominant(Gala’sgenotypeisJJ,Braeburn’sgenotypeisJJ)
Crunchinessisdominant(Gala’sgenotypeisCc,Braeburn’sgenotypeisCC)
Redskincoloringisdominant(Gala’sgenotypeisRR,Braeburn’sgenotypeisRr)
Smoothskintextureisdominant(Gala’sgenotypeisBb,Braeburn’sgenotypeisBb)
2
Apple Genetics
(continued)
CompletethePunnettSquaresandcalculatetheprobabilityofeachgenotypeforalltraits.
Tartness:(Example)
t
T
T
Tt
Tt
Sweetness
S
Tt
Tt
t
s
Probabilityofoffspringgenotypes:
Ss
Ss
Ss
Ss
S
SS=_____0%_____
Tt=_____100%_
Ss=_____100%_____
tt=________0%__
ss=_____0%_____
J
J
Crunchiness
J
JJ
JJ
JJ
JJ
J
Probabilityofoffspringgenotypes:
JJ=____100%______
C
c
C
CC
Cc
CC
Cc
C
Probabilityofoffspringgenotypes:
CC=_____50%_____
Cc=_____50%_____
Jj=_____0%_____
jj=_____0%_____
RedSkinColoring
Probabilityofoffspringgenotypes:
TT=_______0%__
Juiciness
s
cc=______0%____
R
R
RR
R RR
Rr
Rr
r
Probabilityofoffspringgenotypes:
SmoothSkinTexture
B
B BB
b Bb
b
Bb
bb
Probabilityofoffspringgenotypes:
RR=___50%_______
BB=____25%______
Rr=___50%_______
Bb=____50%______
rr=____0%______
bb=____25%______
3
Apple Genetics
(continued)
Part 4: Jazz Apple Observation:ObservethetraitsoftheJazzapple.
JazzAppleObservations
Explainwhatyouobserveontheoutsideandinsideofthisparticularapple.
Writedowneverythingyounotice,stemstructure,seedlayout,andcoloring.
Look
OutsideofApple Redapplewithyellowpatchesandyellowdots
InsideofApple
Smell
Whitecolor
Explainwhatyouobserveusingyoursenseofsmell.
OutsideofApple Littletonosmell,smellslikeapple
InsideOfApple
Nothingdistinctive
Explainwhatyouobserveaboutthetextureoftheapple.i.e.skin,meat,seed,
stem
Touch
OutsideofApple Waxyandsmooth
InsideofApple
Answersmayvary(6-10seedsiscommon),teardropshape
Explainwhatyouobservewhenyoutasteyourapple.
Taste
Tart,butnotasTartasBraeburn
Tartness
Sweet,butnotassweetatGala
Sweetness
Juiciness
VERYJuicy
VERYCrunchy
Crunchiness
4
Apple Genetics
(continued)
Part 5: Comparing Royal Gala, Braeburn, and Jazz Apples
Similaritiesanddifferencesfound:
1. Describesimilaritiesyoufoundamongall3applevarieties.
Allapplesweregood“eating”apples.Theappleswerecrunchyandhadverysimilar
exteriorcharacteristics.
2. Describedifferencesyoufoundamongall3applevarieties.
GalawasthesweetestwhileBraeburnwasthemosttart.SincetheJazzisacrossbetween
thetwo,itwasrightinthemiddle.
Crossbreedingapples
1.
Whichofthethreeappleswasyourfavorite?Why?
Answerswillvary.
2. Whydoapplebreederscrossbreedapplevarieties?
Itallowsbreederstocreatehigherquality,bettertastingvarieties.
5