Download Punnett Square Powerpoint


Key Terms:
› Hybrid – Heterozygous Organism – Ff
› Purebred
 Homozygous Dominant - FF
 Homozygous Recessive – ff
› P Generation – Refers to the parent generation
› F1 – First Generation (first set of offspring)
› F2 – Second Generation (second set of offspring

Mendel, the father of genetics, completed
over 100 experiments examining
inheritance patters (traits) in pea plants

Today, instead of repeating all of his
experiments, we can use Punnett Squares
to predict the traits the offspring will inherit

Monohybrid Cross only studies on trait

Trait: Seed Shape
› Round – Dominant
R
› Wrinkle – Recessive
r
› P1: RR x rr
r
R

Trait: Seed Shape
› Round – Dominant
R
› Wrinkle – Recessive
r
› P1: RR x rr
r
Rr
R

Trait: Seed Shape
› Round – Dominant
› Wrinkle – Recessive
r
› P1: RR x rr
r
R
R
Rr
Rr

Trait: Seed Shape
› Round – Dominant
R
R
r
Rr
Rr
r
Rr
› Wrinkle – Recessive
› P1: RR x rr

Trait: Seed Shape
› Round – Dominant
› Wrinkle – Recessive
› P1: RR x rr

R
r
Rr
Rr
r
Rr
Rr
F1 Genotype:
› Homozygous Dominant =
› Heterozygous =
› Homozygous Recessive =

R
F1 Phenotype:
› Round =
› Wrinkled =

Trait: Seed Shape
› Round – Dominant
› Wrinkle – Recessive
› P1: RR x rr

R
r
Rr
Rr
r
Rr
Rr
F1 Genotype:
› Homozygous Dominant = 0%
› Heterozygous = 4 Rr, 100%
› Homozygous Recessive = 0%

R
F1 Phenotype:
› Round = 4, 100%
› Wrinkled = 0%

Trait: Seed Shape
› Round – Dominant
R
› Wrinkle – Recessive
R
› F1: Rr x Rr
r
r

Trait: Seed Shape
› Round – Dominant
R
› Wrinkle – Recessive
R
› F1: Rr x Rr
r
RR
r

Trait: Seed Shape
› Round – Dominant
› Wrinkle – Recessive
R
› F1: Rr x Rr
r
R
r
RR
Rr

Trait: Seed Shape
› Round – Dominant
R
r
R
RR
Rr
r
Rr
› Wrinkle – Recessive
› F1: Rr x Rr

Trait: Seed Shape
› Round – Dominant
› Wrinkle – Recessive
› F1: Rr x Rr

r
R
RR
Rr
r
Rr
rr
F2 Genotype:
› Homozygous Dominant =
› Heterozygous =
› Homozygous Recessive =

R
F2 Phenotype:
› Round =
› Wrinkled =

Trait: Seed Shape
› Round – Dominant
› Wrinkle – Recessive
R
r
R
RR
Rr
r
Rr
rr
› F1: Rr x Rr

F2 Genotype:
› Homozygous Dominant = 1 RR,
25%
› Heterozygous = 2 Rr, 50%
› Homozygous Recessive = 1 rr,
25%

F2 Phenotype:
› Round = 3, 75%
› Wrinkled = 1, 25%

Trait: Seed Color
› Yellow – Dominant
› Green – Recessive
› Cross a
Homozygous
Dominant with a
Heterozygous
Yellow
› ?x?

Trait: Seed Color
› Yellow – Dominant
› Green – Recessive
› Cross a
Homozygous
Dominant with a
Heterozygous
Yellow
› YY x Yy

Trait: Seed Color
› Yellow – Dominant
› Green – Recessive
› Cross a
Homozygous
Dominant with a
Heterozygous
Yellow
› YY x Yy
Y

Trait: Seed Color
› Yellow – Dominant
› Green – Recessive
› Cross a
Homozygous
Dominant with a
Heterozygous
Yellow
› YY x Yy
Y
Y

Trait: Seed Color
› Yellow – Dominant
› Green – Recessive
› Cross a
Homozygous
Dominant with a
Heterozygous
Yellow
› YY x Yy
Y
Y
Y

Trait: Seed Color
› Yellow – Dominant
› Green – Recessive
› Cross a
Homozygous
Dominant with a
Heterozygous
Yellow
› YY x Yy
Y
Y
y
Y

Trait: Seed Color
› Yellow – Dominant
› Green – Recessive
› Cross a
Homozygous
Dominant with a
Heterozygous
Yellow
› YY x Yy
Y
Y
y
YY
Y

Trait: Seed Color
› Yellow – Dominant
› Green – Recessive
› Cross a
Homozygous
Dominant with a
Heterozygous
Yellow
› YY x Yy
Y
y
Y
Y
YY
YY

Trait: Seed Color
› Yellow – Dominant
› Green – Recessive
› Cross a
Homozygous
Dominant with a
Heterozygous
Yellow
› YY x Yy
Y
Y
Y
YY
YY
y
Yy

Trait: Seed Color
› Yellow – Dominant
› Green – Recessive
Y
Y
Y
YY
YY
y
Yy
Yy
› YY x Yy

Genotype:
› Homozygous Dominant =
› Heterozygous =
› Homozygous Recessive =

Phenotype:
› Yellow =
› Green =

Trait: Seed Shape
› Yellow – Dominant
› Green – Recessive
Y
Y
YY
YY
Yy
Yy
› YY x Yy
Y

Genotype:
› Homozygous Dominant = 2
RR, 50%
y
› Heterozygous = 2 Yy, 50%
› Homozygous Recessive = 0%

Phenotype:
› Yellow = 4, 100%
› Green = 0%

Incomplete dominance or codominance is
when 2 alleles are dominant or expresses

Four O’Clock Japanese Flower
› Red – Dominant
› White – Dominant
 RR – Red
 WW – White
 RW – Pink

Four O’Clock
Japanese Flower
› Red – Dominant
› White – Dominant
 RR – Red
 WW – White
 RW – Pink
› RR x WW

Genotypes:
R
W
W
R

Four O’Clock
Japanese Flower
› Red – Dominant
› White – Dominant
 RR – Red
 WW – White
 RW – Pink
› RR x WW

Genotypes:
R
R
W
RW
RW
W
RW
RW

Four O’Clock
Japanese Flower
R
R
W
RW
RW
W
RW
RW
› Red – Dominant
› White – Dominant
 RR – Red
 WW – White
 RW – Pink
› RR x WW

Genotypes:
› RW = Pink, 100%

Color of Mice
› White – Dominant
B
› Black – Dominant
 WW – White
 BB – Black
 WB – Grey
› BB x WB

Genotypes:
W
B
B

Color of Mice
› White – Dominant
B
B
W
BW
BW
B
BB
BB
› Black – Dominant
 WW – White
 BB – Black
 WB – Grey
› BB x WB

Genotypes:

Color of Mice
› White – Dominant
B
B
W
BW
BW
B
BB
BB
› Black – Dominant
 WW – White
 BB – Black
 WB – Grey
› BB x WB

Genotypes:
› BB = Black, 50%
› WB = Grey, 50%

Polygenic Traits are traits that are
controlled by two or more different genes
› Example:
 Eye Color
 Skin Color

Multiple Alleles for one trait
› Example: Blood Type
Blood Type
Genotype
A
IAIA or IAiO
B
IBIB or IBiO
AB
IA IB
O
iOiO

Blood Type
› Cross:
IA
 IAIA x IBIB

Genotypes:
IB
IB
IA

Blood Type
› Cross:
IA
IA
IB
IA IB
IA IB
IB
IA IB
IA IB
 IAIA x IBIB

Genotypes:

Blood Type
› Cross:
IA
IA
IB
IA IB
IA IB
IB
IA IB
IA IB
 IAIA x IBIB

Genotypes:
› IAIB = AB, 100%

Blood Type
› Cross:
IA
 IAiO x IBiO

Genotypes:
IB
iO
iO

Blood Type
› Cross:
IA
iO
IB
IA IB
IBiO
iO
IAiO
iOiO
 IAiO x IBiO

Genotypes:

Blood Type
› Cross:
IA
iO
IB
IA IB
IBiO
iO
IAiO
iOiO
 IAiO x IBiO

Genotypes:
› IAIB = AB, 25%
› IAiO = A, 25%
› IBiO = B, 25%
› iOiO = O, 25%

Sex Linked Traits are traits coded by the alleles only
on the sex chromosomes (X or Y)

In fruit flies, eye color is determined by the alleles
found on the X chromosome
› Red Eyes – Dominant
› White Eyes – Recessive
 XR – Dominant Allele
 Xr – Recessive Allele

Some sex linked traits in humans include color
blindness (XC XC or XCY) and hemophilia (Xh Xh or
XhY)
Genotype
Sex and Eye Color
XRY
Male; Red Eyes
XrY
Male; White Eyes
XR XR
Female; Red Eyes
XR Xr
Female; Red Eyes
Xr Xr
Female; White Eyes

Fruit Flies
› Cross:


XRY
x
XR
XrXr
Genotypes:
Xr
Xr
Y

Fruit Flies
› Cross:


XRY
x
XR
XrXr
Genotypes:
Xr
Xr
XRXr
Y

Fruit Flies
› Cross:


XRY
x
XrXr
Genotypes:
Xr
Xr
XR
Y
XRXr
XrY

Fruit Flies
› Cross:


XRY
x
XR
Y
Xr
XRXr
XrY
Xr
XRXr
XrXr
Genotypes:

Fruit Flies
› Cross:


XRY
x
XR
Y
Xr
XRXr
XrY
Xr
XRXr
XrY
XrXr
Genotypes:

Fruit Flies
› Cross:


XRY
x
XR
Y
Xr
XRXr
XrY
Xr
XRXr
XrY
XrXr
Genotypes:
› XRXr = Female; Red
Eyes, 50%
› XrY = Male; White
Eyes, 50%

Dihybrid Crosses study 2 traits on a
Punnett Square
› This punnett square will have 16 boxes
instead of 4

Plant Height and Seed Shape
›
›
›
›

Tall = Dominant
Short = Recessive
Round = Dominant
Wrinkled = Recessive
Cross a Tall Round x Short Wrinkled
› All Possible combinations of alleles in
gamete:
 TTRR x ttrr
 TR; TR; TR; TR & tr; tr; tr; tr
TR
tr
tr
tr
tr
TR
TR
TR
TR
TR
TR
TR
tr
TtRr
TtRr
TtRr
TtRr
tr
TtRr
TtRr
TtRr
TtRr
tr
TtRr
TtRr
TtRr
TtRr
tr
TtRr
TtRr
TtRr
TtRr
Phenotye: 16 Tall and Round, 100%

Plant Height and Seed Shape
›
›
›
›

Tall = Dominant
Short = Recessive
Round = Dominant
Wrinkled = Recessive
Cross two heterozygous tall and round:
› ?X?
› All Possible combinations of alleles in
gamete:
?

Plant Height and Seed Shape
›
›
›
›

Tall = Dominant
Short = Recessive
Round = Dominant
Wrinkled = Recessive
Cross two heterozygous tall and round:
› TtRr X TtRr
› All Possible combinations of alleles in
gamete:
?

Plant Height and Seed Shape
›
›
›
›

Tall = Dominant
Short = Recessive
Round = Dominant
Wrinkled = Recessive
Cross two heterozygous tall and round:
› TtRr X TtRr
› All Possible combinations of alleles in
gamete:
 TR; Tr; tR; tr & TR; Tr; tR; tr
TR
Tr
tR
tr
TR
TTRR
TTRr
TtRR
TtRr
Tr
TTRr
TTrr
TtRr
Ttrr
tR
TtRR
TtRr
ttRR
ttRr
tr
TtRr
Ttrr
ttRr
ttrr

Phenotypes:
›
›
›
›

9 Tall and Round – 56%
3 Tall and Wrinkled – 19%
3 Short and Round – 19%
1 Short and Wrinkled – 6%
When you cross 2 heterozygous organisms in a
dihybrid cross, you will always have:
›
›
›
›
9 of the same phenotype – Dominant/Dominant
3 of the same phenotype – Dominant/Recessive
3 of the same phenotype – Recessive/Dominant
1 of the same phenotype – Recessive/Recessive
› 9:3:3:1