Animal Science: Unit 3 Genetics and Breeding
Lesson: Genetics and Heredity
Frameworks: 3.1 and 3.2
Material List:
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PowerPoint
Pictures for interest approach
Punnett Square worksheet
Situation:
 This lesson is designed for an animal science class with students ranging from
grades 10th through 12th. This class has already discussed about different breeds and
safety with animals in agriculture.
Interest Approach:
 Show pictures of parents and children and ask the students to point out similarities
between the parents and the children. Then once the students start pointing out
similarities and differences I will ask the students why they think that there are
similarities between the generations. Then the class will start go in to a discussion
about genetics and heredity.
Objectives:
 Define key terms over genetics and breeding with 80% accuracy.
 Discuss Gregor Mendel and his contributions to genetics with 80% accuracy.
 Create a Punnett square detailing different color characteristics on a pea plant
similar to Gregor Mendel’s experiment.
Reasons to Learn:
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Why should we know about genetics?
Why is Gregor Mendel important to genetics?
Why is it important to understand how punnet squares work?
Questions to Answer:
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What are the terms for this unit?
Who is Gregor Mendel?
What is a punnet square?
How does a punnet square work?
Answers to Questions:
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What are the terms for this unit?
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Cell: The basic unit of life
Chromosome: A strand of genetic material that contains genetic code
Crossbreeding: The breeding of two different pure breeds
Gene: A unit of inheritance composed of DNA
Genetics: the study of heredity
Genotype: Genetic makeup of an animal
Heredity: the passing of traits from parents to offspring
Phenotype: The outward expression of a gene
Purebred breeding: The breeding of animals within the same breed
Reproduction: The process by which new organisms are derived normally
involving the union of the male and female sex cells.
o Alleles: alternative form of a gene (one member of a pair) that is located at
a specific position on a specific chromosome
o Heterozygous: The two genes are different. Ex, Rr
o Homozygous: Both genes are the same. Ex, RR
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Who is Gregor Mendel?
o In 1866 Gregor Mendel discovered principles of inheritance while
working with garden pea plants. He noticed inheritance through selective
cross-breeding of different colored pea plants. He also noticed certain traits
show up in offspring without any blending of parent characteristics. Gregor
Mendel decided to use the garden pea plants because they grow easily, and
abundantly, and are easy to manipulate.
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What is a punnet square?
o Technique for predicting genotype of potential offspring. It considers the
dominant and recessive genes of the male and female parents for one trait.
Homozygous and heterozygous genes are considered.
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How does a punnet square work?
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o This is an example of how to predict the probability of having a wrinkled
seeded offspring. Both parents are heterozygous with the recessive gene
being wrinkled.
o Practice Punnett Square Worksheet
 Will begin at the end of class and will finish at home and will go
over the answers at the beginning of class the next day.
Review
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Ask students questions to learn and have them tell the answers based on what they
learned.
 What is genetics and heredity?
 Who was Gregor Mendal and what was his contribution to genetics?
 What is a punnett square?
 How does a punnett square work?
Punnett square worksheet
Complete the following monohybrid crosses: draw a Punnett square, list the ratio and describe
the offspring. Be sure to remember that the capital letter is dominant.
Example)
GG
GG
A green
pea plant
pea plant (GG) is being crossed with a green
(Gg) yellow is the recessive color.
Gg
G
GenoType=
Gg
G
2 GG: 2 Gg
Gg Phenotype= 4 Green pea plants: 0 yellow pea plants
1) A green pea plant (Gg) is crossed with a yellow pea plant (gg).
2) A tall plant (TT) is crossed with a tall plant (Tt).
3) A tall plant (Tt) is crossed with a short plant (tt).
4) A red flower (Rr) is crossed with a white flower
(rr).
5) A white flower (rr) is crossed with a white flower
(rr).
6) A black chicken (BB) is crossed with a black chicken
(BB).
Complete the following problems. List the parent genotypes, draw and fill in a Punnett square,
and then list the offspring genotypes and phenotypes.
1. A homozygous dominant brown mouse is crossed with a heterozygous brown mouse (tan
is the recessive color).
2. Two heterozygous white (brown fur is recessive) rabbits are crossed.
3. Two heterozygous red flowers (white flowers are recessive) are crossed.
4. A homozygous tall plant is crossed with a heterozygous tall plant (short is the recessive
size).
5. A heterozygous white rabbit is crossed with a homozygous black rabbit.