Bell Ringer
February 06, 2014
School Day 109
Homework:
Punnett Square
Activity
Daily Decimal (DD)
1.
What is the school day to the 2nd Semester as a
decimal not rounded.
Clear Target – Students will be able to use basic
theoretical probability to solve problems.
Genetic Problems
Working with
Punnett Squares
The Punnett Square
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Recall that for each trait, there are two genes
(one from the mother, one from the father)
Let’s use earlobes as an example
Free earlobes are dominant to
attached earlobes
FF = pure dominant or homozygous;
(free earlobes)
Ff = heterozygous; (free earlobes)
ff = pure recessive or homozygous;
(attached earlobes)
The Punnett Square
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Complete the Punnett square to show the
cross between two heterozygous parents
Father’s Genes
F
f
Ff x Ff
Mother’s
Genes
F
f
FF
Ff
Ff
ff
The Punnett Square
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What are the genotypes of offspring with free
earlobes? FF and Ff
If the genotype is ff, what will the phenotype
be (what will it look like)? Attached earlobes
Genotype Ratio: 1FF : 2Ff : 1ff
F
f
F
f
FF
Ff
Ff
ff
The Punnett Square
How many offspring will have free
earlobes? 3
 How many will have attached earlobes? 1
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Attached: 25%
And free earlobes?
Free: 75%
Father’s Genes
What is the probability of
one offspring having attached earlobes?
Mother’s Genes
F
f
F
FF
Ff
f
Ff
ff
The Punnett Square
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The type of chin a person has is also a genetic
trait
A person with a cleft chin has a small
indentation in the middle of their chin
Cleft chin = dominant trait
Smooth chin = recessive trait
The Punnett Square
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I = cleft chin
i = smooth chin
What are all possible genotypes if the father is Ii and
mother is ii?
Ii, ii
What phenotypes will
I
i
the offspring have and
how many will there
Ii
be?
i
ii
50%  cleft chin
50%  smooth chin
i
Ii
ii
SWYK
Use your composition notebook to complete the following:
Heterozygous round pea plant (Rr) “cross (x)”
Heterozygous round pea plant (Rr)
Closure
In your composition notebook, write down what you learned
during today’s lesson.
I learned that_______________.
I am having difficulty in understanding_____________.
I want to learn more about__________________.
Include more details as you write.
Homework
Show the first generation and the second generation of
the following pea plants:
Homozygous round (RR) x heterozygous round (Rr)
1. Write down percent chance statements for round and
wrinkled peas.
2. Now cross two of the offspring’s genotypes and show
the next generation.
3. Write down percent chance statements for round and
wrinkled peas for this Punnett Square.
4. Use Punnett Squares to show your work and write
down all genotypes, phenotypes and corresponding
percentages.