let’s review! alleles are found at the same locus (place) on homologous chromosomes (remember...

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


Take the Last letters in each parentheses and put them in a circle to represent the gamete.

Take this allele And this allele


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


TRTRTR TR(TT)(RR) x

Draw a Punnett square for dihybrid cross…you will need 4 columns and 4 rows



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..



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




6) Fill in the boxes with the correct genotype

TRTR

TRTR


TtRrTtRr TtRrTtRr TtRrTtRr TtRrTtRr



TtRrTtRrTtRrTtRr TtRrTtRr TtRrTtRr


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





TtRrTtRrTtRrTtRr TtRrTtRr TtRrTtRr


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)


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


•L = Last

TR Tr tR tr

9) Follow the same steps to cross the F1 generation and complete the F2 generation

F1


T( t)(Rr) T( t)(Rr)xTR Tr tR tr TR Tr tR tr

F1



trtR

TrTR

TR Tr tR trTTRRTTRR TTRrTTRr TtRRTtRR TtRrTtRr

TTRrTTRr TTrrTTrr TtRrTtRr TtrrTtrr

TtRRTtRR TtRrTtRr ttRRttRR ttRrttRr

TtRrTtRr TtrrTtrr ttRrttRr ttrrttrr

F1

F2



trtR

TrTR





F1

F2

Genotype of Genotype of FF2 2 ::==

TTRRTTRR11

==

TTRrTTRr22

==

TtRRTtRR22

== TtRrTtRr44== TTrrTTrr11== TtrrTtrr22== ttRRttRR11== ttRrttRr22== ttrrttrr11ttRRttRR



trtR

TrTR





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


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


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




•L = Last

AG AG AG AG

(AA)(GG) x (aa)(gg) (AA)(GG) x (aa)(gg) pp ag ag ag ag



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


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




•L = Last

AG Ag aG ag

(Aa)(Gg) x (Aa)(Gg)(Aa)(Gg) x (Aa)(Gg)AG Ag aG ag



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



AG(Aa)(Gg) x (Aa)(Gg) (Aa)(Gg) x (Aa)(Gg)

F1F1

agaG

AgAG





Ag aG ag AG Ag aG ag

== AAGGAAGG11==

AAGgAAGg22

==

AaGGAaGG22

==

AaGgAaGg44

==

AaggAagg22

==

AAggAAgg11

==

aaGGaaGG11

==

aaGgaaGg22

==

aaggaagg11


Key: Key: A=antenA=antennaenaea= a= hornshornsG=greeG=greenng=purplg=purplee


AG(Aa)(Gg) x (Aa)(Gg) (Aa)(Gg) x (Aa)(Gg)

pp

agaG

AgAG





Ag aG ag AG Ag aG ag== AAGGAAGG11==

AAGgAAGg22

==

AaGGAaGG22

==

AaGgAaGg44

==

AaggAagg22

==

AAggAAgg11

==

aaGGaaGG11

==

aaGgaaGg22

== aaggaagg11


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

let’s review! alleles are found at the same locus (place) on homologous chromosomes (remember...

Documents

short pea plantr

tall pea plantt

round seed shaper

wrinkled seed shape2

parents gametes

letters togetherexample

outside letters

inside letters