Thursday, April 4th, 2013
Name: ____________________________________ Period: ____
Describe heredity as the passage of instructions from one generation
Competency
to another and recognize that heredity information is contained in
3d – DOK 2
genes, located in the chromosomes of each cell.
8th Grade –
I can fill in Punnett squares to determine possible offspring genotypes
Lesson 5.4
and phenotypes.
Page
4
Unit 5 – Heredity and Genetics: Punnett Square Introduction
Quick Review
1.
2.
3.
4.
5.
The number of electrons flowing through a wire = current (I), units of amps (A).
The amount of force pushing electrons through a wire = voltage (V), units of volts (V).
How much the wire wants to stop electron movement = resistance (R) units of Ohms (Ω).
If the voltage in a wire increases, the current will increase.
If the resistance in a wire increases, the current will decrease.
Key Points on Punnett Square Introduction:
1. What
a. An organism that is homozygous (DD or dd) is also called a purebred. An organism that is
heterozygous (Dd) is called a hybrid.
b. A Punnett square is a tool that can be used to predict the genotypes and phenotypes of
offspring of produced by mating two parents.
c. The mating of two parents is also called a cross.
2. Why
a. It is very helpful to be able to predict the genotypes and phenotypes of offspring.
b. Scientist making seeds for use on farms may want all of the offspring of a cross to have
certain traits. He or she can use a Punnett square to make sure the offspring will have the
trait.
c. If a parent has a genetic disease, a genetic counselor can determine the two parent’s
alleles and predict the chance of their child having the disease. Parents could use this
information to help them decide to have their own children or to adopt.
3. How
a.
b.
c.
d.
e.
f.
g.
h.
Determine the parents’ genotypes.
Write down your cross.
Draw an empty Punnett square.
Split the letters of the genotype for
each parent and put them on the
outsides of the Punnett square.
Write the letters on the left side of
the square in the two squares on
the right.
Write the letters on top of the square
down in the two squares below.
Determine the genotype of the
offspring.
Determine the phenotype of the
offspring.
Two rabbits with spots are crossed. They are both
hybrids. Setup the Punnett square and determine
the possible genotypes and phenotypes of their
offspring.
Cross:
X
Punnett Square:
Genotypes of Offspring:
Phenotypes of Offspring:
Thursday, April 4th, 2013
Competency
3d – DOK 2
8th Grade –
Lesson 5.4
Name: ____________________________________ Period: ____
Describe heredity as the passage of instructions from one generation to
another and recognize that heredity information is contained in genes,
located in the chromosomes of each cell.
I can fill in Punnett squares to determine possible offspring genotypes and
phenotypes.
Page
4
Unit 5 – Heredity and Genetics: Punnett Square Introduction
Quick Review
1.
2.
3.
4.
5.
The number of electrons flowing through a wire =
The amount of force pushing electrons through a wire =
How much the wire wants to stop electron movement =
If the voltage in a wire increases, the current will
If the resistance in a wire increases, the current will
(
), units of
( ), units of
( ) units of
( ).
( ).
( ).
.
.
Key Points on Punnett Square Introduction:
1. What
a. An organism that is homozygous (
or
) is also called a
. An
organism that is heterozygous (
) is called a
.
b. A Punnett square is a tool that can be used to
the
and
of
produced by
two parents.
c. The mating of two parents is also called a
.
2. Why
a. It is very helpful to be able to
the genotypes and phenotypes of offspring.
b. Scientist making
for use on farms may want all of the offspring of a cross
to have certain traits. He or she can use a Punnett square to make sure the
offspring will have the trait.
c. If a parent has a genetic disease, a
can determine the two
parent’s alleles and predict the chance of their child
.
Parents could use this information to help them decide to have their own children
or to adopt.
3. How
a. Determine the parents’
. Two rabbits with spots are crossed. They are both
hybrids. Setup the Punnett square and determine
b. Write down your
.
c. Draw an empty
square. the possible genotypes and phenotypes of their
d.
the
of the genotype offspring.
for each parent and put them on
Cross:
X
the
of the Punnett square. Punnett Square:
e.
the letters on the
side of the square in the
on the
.
f.
the letters on
of the
square
in the ______
.
g. Determine the
of the offspring.
Genotypes of Offspring:
h. Determine the
Phenotypes of Offspring:
of the offspring.
Thursday, April 4th, 2013
Name: ____________________________________ Period: ____
Punnett Square Introduction: Guided Practice
A homozygous dominant tall plant is crossed with a
homozygous recessive short plant. Setup the Punnett
square and determine the possible genotypes and
phenotypes of their offspring.
X
A hybrid with round seeds is crossed with a
homozygous dominant plant. Setup the Punnett
square and determine the possible genotypes and
phenotypes of their offspring. The phenotype of the
recessive allele is oval shaped seeds.
Punnett Square Introduction: Independent Practice
Directions: Answer the following questions in complete sentences.
1. KP1a: What are the two possible genotypes of an organism if it is considered a purebred?
2. KP3a: What must be known to predict the genotypes and phenotypes of offspring?
3. KP2a: How can a Punnett square be useful?
Horses have a gene for coat color. The dominant allele gives a brown (B) coat while the
recessive allele gives a white (b) coat. A breeder is crossing a purebred brown horse with a
hybrid brown horse.
4. Use letters to show the genotypes of the two parents that are being crossed.
5. Setup and fill in the Punnett square to show the genotypes of the offspring.
6.
What are the possible phenotypes of the offspring?