Let’s review!Let’s review!
Alleles are found at the same locus Alleles are found at the same locus (place) on homologous chromosomes (place) on homologous chromosomes (remember pairs)(remember pairs)
Homozygotes (pure breds) Homozygotes (pure breds)
YY yy
or
Heterozgote (hybrid) Heterozgote (hybrid)
Yy
Recessive Allele is only expressed in Recessive Allele is only expressed in a homozygote a homozygote
yy
Phenotype (appearance) Phenotype (appearance)
Yellow Green
or
Genotype (combination of alleles) Genotype (combination of alleles)
YY Yyor yyor
Monohybrid Cross - one Monohybrid Cross - one characteristic is used characteristic is used
Key:
Y=yellow
y=greenYY yy
or
Dihybrid Cross - two characteristics Dihybrid Cross - two characteristics are used are used
Key:
Y=yellow
y=green
S=smooth
s=wrinkled
YYSS yyss
or
Dihybrid CrossesDihybrid Crosses
Chapter 11-3 Exploring Chapter 11-3 Exploring Medelian GeneticsMedelian Genetics
Do genes separate?Do genes separate?
Yes, genes Yes, genes separateseparate independently, even if you independently, even if you have more than one type of have more than one type of gene.gene.
This help us in solving This help us in solving dihybrid crosses (crosses dihybrid crosses (crosses involving involving twotwo traits) traits)
Let’s work a problem!!!!Let’s work a problem!!!!
1) Write a key
Key:
T=tall pea plant
t=short pea plant
R=round seed shape
r=wrinkled seed shape
2) Write the genotype of the parents as a cross and label them as P (for parent generation)
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shapeTTRR x ttrr
P
3) Show what alleles are available from the gametes of the parents USING THE FOIL METHOD
TR TR TR TR P
TTRR x ttrr(TT)(RR) x (tt)(rr)
Write parenthesis around the different characteristics in each parent.
NOw use the FOIL method to make gametes….
Take the first letters in each parentheses and put them in a circle to represent the gamete.
Take this allele And this allele Combined
to make this gamete
Take this allele And this allele
Combined to make this gamete
Take the Outside letters in each parentheses and put them in a circle to represent the gamete.
Take the Inside letters in each parentheses and put them in a circle to represent the gamete.
Take this alleleAnd this allele
Combined to make this gamete
Take the Last letters in each parentheses and put them in a circle to represent the gamete.
Take this allele And this allele
Combined to make this gamete
Each parent will have four gametes.
The foil method goes:•F = First•O = Outside•I = Inside
•L = Last
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shape
3) Show what alleles are available from the gametes of the parents USING THE FOIL METHOD TRTRTR TR
(TT)(RR) x
NOw use the FOIL method to make gametes for the second parent
REMEMBER!!! The foil method goes:•F = First•O = Outside•I = Inside
•L = Last
t( t)(rr)tr tr tr tr
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shape
TRTRTR TR(TT)(RR) x
Draw a Punnett square for dihybrid cross…you will need 4 columns and 4 rows
t( t)(rr)tr tr tr tr
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shape
4) Draw a Punnett square for a dihybrid cross
TRTRTR TR(TT)(RR) x
Fill in the first parent’s gametes on the left hand side and the second on top..
t( t)(rr)tr tr tr tr
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shape
5) Put the gametes on the square
TRTR
TRTR
(TT)(RR) x t( t)(rr)tr tr tr tr
TtRrTtRr
Keep the letters Keep the letters together…Example: together…Example: T’s with T’s and R’s T’s with T’s and R’s with R’s…with R’s…
Be consistent…Keep the Be consistent…Keep the first two letters the same first two letters the same throughout the square… throughout the square… ex: T’s 1ex: T’s 1stst and R’s and R’s second…second…
Fill in the boxes…Fill in the boxes…
TtRrTtRrTtRrTtRrTtRrTtRr
TtRrTtRrTtRrTtRrTtRrTtRrTtRrTtRr
TtRrTtRrTtRrTtRrTtRrTtRrTtRrTtRr
TtRrTtRrTtRrTtRrTtRrTtRrTtRrTtRr
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shape
6) Fill in the boxes with the correct genotype
TRTR
TRTR
(TT)(RR) x t( t)(rr)tr tr tr tr
TtRrTtRr TtRrTtRr TtRrTtRr TtRrTtRr
TtRrTtRr TtRrTtRr TtRrTtRr TtRrTtRr
TtRrTtRr TtRrTtRr TtRrTtRr TtRrTtRr
TtRrTtRrTtRrTtRr TtRrTtRr TtRrTtRr
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shape
7) Write the genotype and phenotype for the F1 generation
Genotype of Genotype of FF1 1 ::
F1
16 = TtRr16 = TtRr
Phenotype of Phenotype of FF1 1 ::16 = tall and 16 = tall and round seed round seed shapeshape
TRTR
TRTR
(TT)(RR) x t( t)(rr)tr tr tr tr
TtRrTtRr TtRrTtRr TtRrTtRr TtRrTtRr
TtRrTtRr TtRrTtRr TtRrTtRr TtRrTtRr
TtRrTtRr TtRrTtRr TtRrTtRr TtRrTtRr
TtRrTtRrTtRrTtRr TtRrTtRr TtRrTtRr
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shape
8) Take two from the F1 generation to cross to find out the genotype and phenotype of the F2 generation (all the same, choose two)
Genotype of Genotype of FF1 1 ::
F1
16 = TtRr16 = TtRr
Phenotype of Phenotype of FF1 1 ::16 = tall and 16 = tall and round seed round seed shapeshape
T( t)(Rr) T( t)(Rr)x
REMEMBER!!! The foil method goes:•F = First•O = Outside•I = Inside
•L = Last
TR Tr tR tr
9) Follow the same steps to cross the F1 generation and complete the F2 generation
F1
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shape
T( t)(Rr) T( t)(Rr)xTR Tr tR tr TR Tr tR tr
F1
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shape
T( t)(Rr) T( t)(Rr)xTR Tr tR tr TR Tr tR tr
trtR
TrTR
TR Tr tR trTTRRTTRR TTRrTTRr TtRRTtRR TtRrTtRr
TTRrTTRr TTrrTTrr TtRrTtRr TtrrTtrr
TtRRTtRR TtRrTtRr ttRRttRR ttRrttRr
TtRrTtRr TtrrTtrr ttRrttRr ttrrttrr
F1
F2
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shape
T( t)(Rr) T( t)(Rr)xTR Tr tR tr TR Tr tR tr
trtR
TrTR
TR Tr tR trTTRRTTRR TTRrTTRr TtRRTtRR TtRrTtRr
TTRrTTRr TTrrTTrr TtRrTtRr TtrrTtrr
TtRRTtRR TtRrTtRr ttRRttRR ttRrttRr
TtRrTtRr TtrrTtrr ttRrttRr ttrrttrr
F1
F2
Genotype of Genotype of FF2 2 ::==
TTRRTTRR11
==
TTRrTTRr22
==
TtRRTtRR22
== TtRrTtRr44== TTrrTTrr11== TtrrTtrr22== ttRRttRR11== ttRrttRr22== ttrrttrr11ttRRttRR
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shape
T( t)(Rr) T( t)(Rr)xTR Tr tR tr TR Tr tR tr
trtR
TrTR
TR Tr tR trTTRRTTRR TTRrTTRr TtRRTtRR TtRrTtRr
TTRrTTRr TTrrTTrr TtRrTtRr TtrrTtrr
TtRRTtRR TtRrTtRr ttRRttRR ttRrttRr
TtRrTtRr TtrrTtrr ttRrttRr ttrrttrr
F1
F2
Genotype of FGenotype of F2 2 ::== TTRRTTRR
Phenotype of Phenotype of FF2 2 ::99
11== TTRrTTRr22== TtRRTtRR22== TtRrTtRr44== TTrrTTrr11== TtrrTtrr22== ttRRttRR11== ttRrttRr22== ttrrttrr11
=tall and round seed =tall and round seed shapeshape==tall and wrinkled seed tall and wrinkled seed shapeshape
Key:T=tall pea plantt=short pea plantR=round seed shaper=wrinkled see shape
33
==short and round seed short and round seed shapeshape
33
==short and wrinked short and wrinked seed shapeseed shape
11
Wow…you did it!!! Good job…. All you have to do is follow the steps!
And now for something really original!And now for something really original!
In aliens from outer space, having In aliens from outer space, having ANTENNAEANTENNAE is dominant over having is dominant over having hornshorns AND AND GREENGREEN skin is dominant over skin is dominant over purplepurple skin. skin.
Key: Key: A=antennaeA=antennae a= hornsa= horns G=greenG=green g=purpleg=purple
Another Dihybrid problem…Another Dihybrid problem…On your own!!!!On your own!!!!
Key: Key: A=antennaeA=antennaea= hornsa= hornsG=greenG=greeng=purpleg=purple
Cross a Cross a homozygous antennaehomozygous antennae alien that alien that is is homozygous greenhomozygous green with a with a homozygous homozygous hornedhorned alien that is alien that is homozygous purplehomozygous purple..
What would the parent’s genotype look What would the parent’s genotype look like?like?
AAGG x aagg AAGG x aagg pp
Key: Key: A=antennaeA=antennaea= hornsa= hornsG=greenG=greeng=purpleg=purple
Cross a Cross a homozygous homozygous antennaeantennae alien that is alien that is homozygous greenhomozygous green with a with a homozygous homozygous hornedhorned alien that is alien that is homozygous purplehomozygous purple..
AAGG x aagg AAGG x aagg pp
•Write the parenthesis around parents alleles
(AA)(GG) x (aa)(gg) (AA)(GG) x (aa)(gg) pp
Key: Key: A=antennaeA=antennaea= hornsa= hornsG=greenG=greeng=purpleg=purple
Cross a Cross a homozygous homozygous antennaeantennae alien that is alien that is homozygous greenhomozygous green with a with a homozygous homozygous hornedhorned alien that is alien that is homozygous purplehomozygous purple..
REMEMBER!!! The foil method goes:•F = First•O = Outside•I = Inside
•L = Last
AG AG AG AG
(AA)(GG) x (aa)(gg) (AA)(GG) x (aa)(gg) pp ag ag ag ag
Key: Key: A=antennaeA=antennaea= hornsa= hornsG=greenG=greeng=purpleg=purple
Cross a Cross a homozygous homozygous antennaeantennae alien that is alien that is homozygous greenhomozygous green with a with a homozygous homozygous hornedhorned alien that is alien that is homozygous purplehomozygous purple..
AG(AA)(GG) x (aa)(gg) (AA)(GG) x (aa)(gg)
ppag
AGAG
AGAG
ag ag ag agAaGgAaGgAaGgAaGg AaGgAaGg AaGgAaGg
AaGgAaGgAaGgAaGg AaGgAaGg AaGgAaGg
AaGgAaGgAaGgAaGg AaGgAaGgAaGgAaGg
AaGgAaGgAaGgAaGg AaGgAaGg AaGgAaGg F1
AG AG AG ag ag ag
Genotype of Genotype of FF1 1 ::16 = AaGg16 = AaGg
Phenotype of Phenotype of FF1 1 ::16 = 16 = antennae antennae and greenand green
Key: Key: A=antennaeA=antennaea= hornsa= hornsG=greenG=greeng=purpleg=purple
Cross a Cross a heterozygous antennaeheterozygous antennae alien that is alien that is heterozygous greenheterozygous green with a with a heterozygous heterozygous antennaeantennae alien that is alien that is heterozygous greenheterozygous green
What would the parent’s genotype look like?What would the parent’s genotype look like?
AaGg x AaGg AaGg x AaGg FF11
Key: Key: A=antenA=antennaenaea= a= hornshornsG=greeG=greenng=purplg=purplee
Cross a Cross a heterozygous heterozygous antennaeantennae alien that is alien that is heterozygous greenheterozygous green with a with a heterozygous heterozygous antennaeantennae alien that is alien that is heterozygous greenheterozygous green . .
AaGg x AaGg AaGg x AaGg pp
•Rewrite the parents with parenthesis
(AA)(GG) x (aa)(gg) (AA)(GG) x (aa)(gg) FF11
Key: Key: A=antennaeA=antennaea= hornsa= hornsG=greenG=greeng=purpleg=purple
Cross a Cross a homozygous homozygous antennaeantennae alien that is alien that is homozygous greenhomozygous green with a with a homozygous homozygous hornedhorned alien that is alien that is homozygous purplehomozygous purple..
REMEMBER!!! The foil method goes:•F = First•O = Outside•I = Inside
•L = Last
AG Ag aG ag
(Aa)(Gg) x (Aa)(Gg)(Aa)(Gg) x (Aa)(Gg)AG Ag aG ag
Key: Key: A=antennaeA=antennaea= hornsa= hornsG=greenG=greeng=purpleg=purple
Cross a Cross a homozygous homozygous antennaeantennae alien that is alien that is homozygous greenhomozygous green with a with a homozygous homozygous hornedhorned alien that is alien that is homozygous purplehomozygous purple..
AG(Aa)(Gg) x (Aa)(Gg)(Aa)(Gg) x (Aa)(Gg)
agaG
AgAG
AG Ag aG agAAGGAAGGAAGgAAGg AaGGAaGG AaGgAaGg
AAGgAAGgAAggAAgg AaGgAaGg AaggAagg
AaGGAaGGAaGgAaGg aaGGaaGGaaGgaaGg
AaGgAaGgAaggAagg aaGgaaGg aaggaagg F1
Ag aG ag AG Ag aG ag
Key: Key: A=antennaeA=antennaea= hornsa= hornsG=greenG=greeng=purpleg=purple
Cross a Cross a homozygous homozygous antennaeantennae alien that is alien that is homozygous greenhomozygous green with a with a homozygous homozygous hornedhorned alien that is alien that is homozygous purplehomozygous purple..
AG(Aa)(Gg) x (Aa)(Gg) (Aa)(Gg) x (Aa)(Gg)
F1F1
agaG
AgAG
AG Ag aG agAAGGAAGGAAGgAAGg AaGGAaGG AaGgAaGg
AAGgAAGgAAggAAgg AaGgAaGg AaggAagg
AaGGAaGGAaGgAaGg aaGGaaGGaaGgaaGg
AaGgAaGgAaggAagg aaGgaaGg aaggaagg F2
Ag aG ag AG Ag aG ag
== AAGGAAGG11==
AAGgAAGg22
==
AaGGAaGG22
==
AaGgAaGg44
==
AaggAagg22
==
AAggAAgg11
==
aaGGaaGG11
==
aaGgaaGg22
==
aaggaagg11
Genotype of Genotype of FF1 1 ::
Key: Key: A=antenA=antennaenaea= a= hornshornsG=greeG=greenng=purplg=purplee
Cross a Cross a homozygous homozygous antennaeantennae alien that is alien that is homozygous greenhomozygous green with a with a homozygous homozygous hornedhorned alien that is alien that is homozygous purplehomozygous purple..
AG(Aa)(Gg) x (Aa)(Gg) (Aa)(Gg) x (Aa)(Gg)
pp
agaG
AgAG
AG Ag aG agAAGGAAGGAAGgAAGg AaGGAaGG AaGgAaGg
AAGgAAGgAAggAAgg AaGgAaGg AaggAagg
AaGGAaGGAaGgAaGg aaGGaaGGaaGgaaGg
AaGgAaGgAaggAagg aaGgaaGg aaggaagg F1
Ag aG ag AG Ag aG ag== AAGGAAGG11==
AAGgAAGg22
==
AaGGAaGG22
==
AaGgAaGg44
==
AaggAagg22
==
AAggAAgg11
==
aaGGaaGG11
==
aaGgaaGg22
== aaggaagg11
Genotype of Genotype of FF1 1 ::
Phenotype of FPhenotype of F1 1 ::9933
33
11
=antennae and green=antennae and green==antennae and purpleantennae and purple
==horns and greenhorns and green
==horns and purplehorns and purple
Dihybrid Homework Dihybrid Homework ProblemProblem
In aliens from outer space, having In aliens from outer space, having ANTENNAEANTENNAE is dominant over having is dominant over having hornshorns AND AND GREENGREEN skin is dominant over skin is dominant over purplepurple skin. skin.
Cross an alien from outer space that is Cross an alien from outer space that is Homozygous antennae and heterozygous Homozygous antennae and heterozygous green with another that is Homozygous green with another that is Homozygous horns and heterozygous green.horns and heterozygous green.
Show the genotype and phenotypeShow the genotype and phenotype
http://biology.clc.uc.edu/cohttp://biology.clc.uc.edu/courses/bio105/geneprob.htmurses/bio105/geneprob.htm