Think about how your features compare with your parents……
What color eyes do you have? What color eyes do your parents have?
If we know the genotypes of the parents we can predict the traits of their offspring.

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Sponge Bob Square Pants!!!! :)

1. Scientists at Bikini Bottoms have been investigating the genetic makeup of the organisms in this community.
Use the information provided and your knowledge of genetics to answer the following questions: For each Genotype below indicate whether it is heterozygous (He) or
Homozygous (Ho).

For Each Phenotype, give the genotypes that are possible for Patrick

Create a Punnett square to show the possibilities that would result if Sponge Bob and
Sponge Susie had children.

A Punnett Square
A Punnett Square is a graph used to determine all possible combinations of genotypes of offspring and their probability of occurrence.

Determine the genotype of each parent.
Example Problem:
Cross a Sponge Bob (heterozygous square) with Susie Roundpants (homozygous round)
Answer:
The Cross is Ss x ss

Draw A Punnett Square

Seperate the alleles of each parent & put outside the squares.
FOR OUR
CROSS
Ss x ss s ss s
Ss
S s

Fill in the Punnett Square to determine offspring genotypes.
Ss ss s s
S s
Ss s s
S s s s

1. Report the resulting genotypes of
Bb
2. Then determine phenotype based on dominant traits.
GENOTYPES: PHENOTYPES:
Ss ss
50% Ss
50% ss
Ss = Square ss = round
Ss ss
RESULTS: Probability of square children is 50% and Probability of round children is 50%

Create a Punnett square to show the possibilities that would result if Sponge Bob and
Sponge Susie had children.

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The Law of Segregation – Because each organism has two different alleles, it passes one allele for each trait at random to each offspring.

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The law of independent
assortment – Genes for different traits are inherited independently of each other.
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For example: Eye color & Hair Color is inherited independently.

Basic Steps To Complete a Punnett Square
1. Determine the genotype of each parents and determine your cross.
2. Draw Punnett Square.
3. Separate the alleles of each parent & place them outside the square.
4. Fill in the Punnett Square to determine combinations of alleles (genotypes).
5. Report your results and determine phenotypes.

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A Dihybrid Cross is a cross in which two traits are considered.
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Mendel performed a dihybrid cross with pea plants. He crosses both seed shape and seed color.

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We can cross parents with two traits. The parents genotypes are TTRR and ttrr.
T= Tall t = short
R= round r = wrinkled
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What are the phenotypes of the parents?

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In a dihybrid cross traits are inherited independently from each other. (Law of
Independent Assortment)
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In order to set up your punnett square for a dihybrid cross you must find all the possible combinations that can be passed on for each parent. (All the possible gamete genotypes)
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Dihybrid
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What are the 4 combinations of parent TtRr?

T t R r