Punnett squares

Punnett squares

The tool which The tool which uses the uses the

combination of combination of alleles to predict alleles to predict the probability of the probability of traits showing up traits showing up

in offspring.in offspring.

Green eyes are dominant and yellow eyes are recessive. The genotype of two insects are Gg and

Gg.Complete a Punnett

square!

G

Gg

GgGG

g

G

g

??

?? = gg

What % of the young would have green

eyes?

Yellow eyes?75%

25%

If B=black and b=brown and two wolves are

heterozygous Bb and homozygous bb what would

their young be?

Complete a Punnett square!

B

Bb

bbBb

b

b

b

bb

What % of young would be black and what % would be

brown? Black = 50 %Brown = 50 %

B=Brown eyes which are dominant, b=blue

eyes which are recessive

What are the alleles of the parents for the

following chart?

B

Bb

BbBB

b

B

b

bb

The parents would be Bb and Bb and both would have

brown eyes!

Curly hair is dominant, and a

couple have curly hair. How many of

their babies will have curly hair?

A. All of the babies B. Probably most of the babiesC. None of the babies

Answer - B

What percent of your genes come from

each parent?

50%

What % of genes come from each

grandparent?

25%

If green snake skin is dominant and

yellow is recessive, what are the alleles of the

parent snakes for the following:

G

Gg

GgGg

g

g

G

Gg

Homozygous (GG) green

Homozygous (gg) yellow

How many different Punnett squares can

you think of?

If big ears are dominant and both

parents are homozygous

dominant, what percent of babies will

have big ears?

E

EE

EEEE

E

E

E

EE

100%

Three fingers is dominant and five

fingers recessive. If mom is homozygous dominant and dad is heterozygous, what percent of young will have three fingers?

F

Ff

FFFF

f

F

F

Ff

100%

Big noses are dominant and little noses are recessive. If Dad is

homozygous dominant and mom is

homozygous recessive, what percent of

children will have big honkers?

N

Nn

NnNn

n

n

N

Nn

100%

Short is dominant and tall is recessive. If dad

is heterozygous dominant and mom is

homozygous recessive, what percent of the children will be short

and tall?

S

Ss’

s’s’

Ss’

s’

s’

s’

s’s’

50% short

50% tall

Long neck is dominant and short neck is

recessive. If dad is heterozygous dominant

and mom is heterozygous

dominant, what percent of the children will have

long necks and short necks?

N

Nn

NnNN

n

N

n

nn

75% Long

25% Short

Short tongues are dominant and long are recessive. If mom is

homozygous recessive and dad is homozygous recessive, what percent of the children will have

long tongues?

t

tt

tttt

t

t

t

tt

100%

CROSSING TWO TRAITS

• CROSS A HOMOZYGOUS TALL , HETEROZYGOUS GREEN PEA PLANT WITH A HOMOZYGOUS SHORT, HOMOZYGOUS YELLOW PLANT.

• TTGg X ttgg

TTGg x ttgg1

2

34

56

78

1

TG 2

Tg 3

TG

4

Tg

5

tg

6

tg

7

tg

8

tg

TtGg Ttgg TtGg Ttgg

TtGg Ttgg TtGg Ttgg

TtGgTtggTtGg

Ttgg

Ttgg

TtGg Ttgg TtGg

1

TG 2

Tg 3

TG 4

Tg 5

tg

6

tg

7

tg

8

tg

TtGg Ttgg TtGg Ttgg

TtGg Ttgg TtGg Ttgg

TtGg Ttgg TtGg Ttgg

TtGg Ttgg TtGg Ttgg

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

TtGg = 8/16Heterozygous TallHeterozygous Green

Ttgg = 8/16Heterozygous Tall

Homozygous Yellow

Genotypes and percentages Phenotypes and percentages

Thank you