1. Punnett Squares Punnett Squares show:
1. The alleles in the gametes of each parent,
2. Possible results of genetic crosses, and
3. The genotypes of the offspring.
Steps to Creating and Using Punnett Squares:
1. Identify the trait and possible alleles (dominant and recessive)
2. Determine the genotype of the parents
3. Create the Punnett Square - each trait needs 2 boxes to represent it
4. Put the male across the top, Female along the side.
5. Fill in the Punnett Square representing the offspring produced
6. Determine the Genotype Ratio (GR) of the offspring.
7. Determine the Phenotype Ratio (PR) of the offspring.

2. Punnett Squares 1. Trait = gender.
2. Genotype of a male = ___. Genotype of a female = ___.
3. Create the punnett square -
2 boxes per trait across the top x 2 boxes per trait down the side
4. Put the dad’s genotype across the top, mom’s down the side
5. Fill in the punnett square for the offspring
6. Determine the offsprings’ genotypes.
7. Determine the offsprings’ phenotypes. XY XX
Law of Segregation X Y X
X X
X Y X
X X
X Y
__ offspring genotype ___: __ offspring genotype ___ = ratio of ______:_______ 2 XX 2 XY
2 XX
2 XY
__ offspring phenotype ____: __ offspring phenotype ____ = ratio of ______:______ 2
girls 2
boys
2 girls
2 boys

3. Probability
Seed shape: Round is dominant (R), Wrinkled = recessive (r)
P Generation Cross - True homozygous dominant/recessive parents
Genotype
Phenotype
RR =
Round
R R
Homozygous Dominant r Rr Rr
Rr =
Heterozygous
Round Rr Rr
rr =
Homozygous Recessive
Wrinkled
0:4:0 Ratio
4:0 Ratio
F1 Generation Cross - Hybrid (heterozygous) offspring
RR =
Homozygous Dominant
Round
R r
Rr =
Heterozygous
Round
R r RR Rr Rr rr
rr =
Homozygous Recessive
Wrinkled
1:2:1 Ratio
3:1 Ratio

4. Punnett Square Practice
Hair Color
Eye Color
Plant Height
Flower Color
D d
E e
t t
p p d Dd dd E e EE Ee T t Tt Tt P Pp Pp Dd dd Ee ee tt tt Pp Pp
Genotypes ___________ ________________ ________________ _________________
Phenotypes __________ ________________ ________________ _________________
2 Bb, 2 bb
2 brown, 2 blonde
Trait
Dominant/Recessive
Parents Genotypes
Dimples
Yes = Dominant = D
Heterozygous dad
No = Recessive = d
Homozygous recessive mom
Earlobes
Detached = Dominant = E
Attached = Recessive = e
Heterozygous mom
Plant Height
Tall = Dominant = T
Homozygous recessive male
Short = Recessive = t
Heterozygous female
Flower Color
Purple = Dominant = P
White = Recessive = p
Homozygous dominant female

5. Independent Assortment
The idea that different traits sort themselves separately (independently)
of each other. For example earlobes and dimples color are two separate
traits and will be represented on 2 separate genes:
Earlobes: Detached (E)
Attached (e)
Dimples: Yes (D)
No (d) o o
FOIL Method f f
Dad: EEDD Mom: eedd i i L L ED ED ED ED ed
EeDd
What are the genotypes of all of the babies? ed
What are the phenotypes of all of the babies? ed ed 5

6. Independent Assortment
The idea that different traits sort themselves separately (independently)
of each other:
Dad: EeDd Mom: EeDd
Earlobes: Detached (E)
Attached (e)
Dimples: Yes (D)
No (d) o o f f i L i L ED Ed eD ed ED
EEDD
EEDd
Where’s the attached earlobe, no dimple baby? Ed
EEdd
Eedd
Where’s an attached earlobe, dimpled baby? eD
eeDD
eeDd
Where’s a detached earlobe, no dimple baby? ed
Eedd
eedd
eedd 6

7. Monohybrid Crosses - from handout
7. Heterochromia
h h
Dad = ____, Mom = ____
Offspring :
Genotypes __________________________________________
Phenotypes _________________________________________ H Hh Hh Hh Hh
8. Heterochromia
h h
Dad = ____, Mom = ____
Offspring :
Genotypes __________________________________________
Phenotypes _________________________________________ h hh hh hh hh
heterochromia (Greek: heteros 'different' + chroma 'color'[1]) is a difference in coloration, usually of the iris but also of hair or skin. Heterochromia is a result of the relative excess or lack of melanin (a pigment). It may be inherited, or caused by genetic mosaicism, chimerism, disease, or injury.[2]
Heterochromia of the eye (heterochromia iridis or heterochromia iridum; the common incorrect form "heterochromia iridium" is not correct Latin) is of two kinds. In complete heterochromia, one iris is a different color from the other. In partial heterochromia or sectoral heterochromia, part of one iris is a different color from its remainder.
Eye color, specifically the color of the irises, is determined primarily by the concentration and distribution of melanin.[3][4][5] The affected eye may be hyperpigmented (hyperchromic) or hypopigmented (hypochromic).[6] In humans, usually, an excess of melanin indicates hyperplasia of the iris tissues, whereas a lack of melanin indicates hypoplasia.
9. Forelock
F f
Dad = ____, Mom = ____
Offspring :
Genotypes __________________________________________
Phenotypes _________________________________________ f Ff ff Ff ff

8. SeX-Linked Chromosome Disorders
Colorblind
Hemophilia
Muscular Dystrophy
Dad - color blind
Mom - a carrier
Dad - normal blood clotting
Mom - a Hemophilia
Dad - Muscular Dystrophy
Mom - normal
How does the world look to a
color blind person? Xc Y XH Y Xd Y XC
XCXc
XCY Xh
XHXh
XhY XD
XDXd
XDY
XcXc
XcY
XHXh Xc Xh
XhY
XDXd
XDY XD
G: ____________
____________
1 heterozy: 1 homozy rec
G: ____________
____________
2 heterozygous females
G: ____________
____________
2 heterozygous females
1 dom male, 1 recessive
2 recessive males
2 dominant males
P: ____________
____________
P: ____________
____________
2 normal carrier females
1 Normal carrer: 1 Colorblind
P: ____________
____________
2 normal carrier females
2 hemophiliac males
1 normal male
1 Colorblind male
2 normal males