Lab 7 Punnett Squares

 

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Complete your answers in the spaces provided. USE YOUR OWN WORDS – Yes even

for definitions! Remember to add your last name and first initial to the file name prior to

saving and submitting your completed assignment through Canvas.

 

 

 

 

 

Use your textbook, notes and this website to answer the pre lab questions.

 

http://www.biology.arizona.edu/Mendelian_genetics/mendelian_genetics.html

 

 

 

PreLab Questions:

 

 

 

1. Define the terms haploid and diploid.

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2. What information do we gain from doing a punnett square?

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3. Define the term allele.

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4. How many copies of each trait are contained in a single gamete?

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Click on the link below to access the online lab.

 

 

 

http://www.mhhe.com/biosci/genbio/virtual_labs_2K8/pages/PunnettSquares.html

 

 

 

Download and print the instructions for reference as you work through the lab. As you

work through the lab fill in the table below. Use this information to answer the questions

that follow contained in this document.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

Complete all ten scenarios and record your results in Table 1.

 

 

 

When you record a ratio, whether it is genotypic or phenotypic ratio, always record the

most dominant characteristic first, followed by the recessive.

 

 

 

Offspring Genotypes

 

Genotypic Ratio

 

Phenotypic Ratio*

 

1 GG, 2 Gg, and 1 gg

 

1 GG : 2 Gg : 1 gg

 

3:1

 

2 GG and 2 Gg

 

2 GG : 2 gg

 

1:1

 

4 gg

 

4 gg

 

0:4

 

 

 

* With monohybrid standard dominance traits there are only 2 possible phenotypes. The

dominant and the recessive. You always report the dominant phenotype first followed by

the recessive phenotype.

 

 

 

 

 

 

Table 1:

 

Scenario #

 

Genotype of

Parent I

 

Genotype of

Parent II

 

Genotypic Ratio

of Offspring

 

Phenotypic Ratio

of Offspring

 

1

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

3

 

 

 

 

 

 

 

 

 

4

 

 

 

 

 

 

 

 

 

5

 

 

 

 

 

 

 

 

 

6

 

 

 

 

 

 

 

 

 

7

 

 

 

 

 

 

 

 

 

8

 

 

 

 

 

 

 

 

 

9

 

 

 

 

 

 

 

 

 

10

 

 

 

 

 

 

 

 

 

 

 

 

 

Post Lab Questions

 

 

 

5. If you mate two black flies what color(s) can their offspring be and why?

 

 

 

 

 

 

 

 

 

6. How can two flies with normal wings have offspring with vestigial wings?

 

 

 

 

 

 

 


 

 

 

7. Someone removed the labels from your fly jars. You have a jar of gray flies. Do you

know their genotype? Why or why not?

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8. You mate two gray normal winged flies and get offspring which are all gray but 25%

of them have vestigial wings. What are the genotypes of the flies you mated? Explain

your answer.

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9. Explain how many phenotypes are there for a trait that has two alleles that are

governed by incomplete dominance.

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10. Explain how many phenotypes are there for a trait that has two alleles that are

governed by co- dominance.

 

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