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Monohybrid (One-Gene)

 

Monohybrid II

Introduction

Now that you can tell the probability of your sister who has blue eyes, is the offspring of both of your parents who have brown eyes. Today, lets try a few more problems.

Part II: Now its time to practice more Punnett Squares.

If you are experimenting with seagulls, where white feathers are dominate over grey feathers. (Use the letter "W"). Make the following crosses:

   
  1. If the mother is homozygous recessive, and the father is homozygous dominate.
  2. Write the genotype probabilities.

 

 

  1. Write the phenotype probabilities.
  1. If the mother is heterozygous, and the father is heterozygous.

 

  1. Write the genotype probabilities.

 

  1. Write the phenotype probabilities.
  1. If the mother is heterozygous, and the father is homozygous dominate.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.
  1. If the mother is homozygous recessive, and the father is heterozygous.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.

 

Part III: Ready for practice more Punnett Squares?

If you are experimenting with flies, where red eyes are dominate over white eyes. (Use the letter "R"). Make the following crosses:

  1. If the mother is heterozygous recessive, and the father is homozygous recessive.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.
  1. If the mother has white eyes, and the father is heterozygous.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.
  1. If the mother is heterozygous, and the father is homozygous dominate.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.
  1. If the mother is homozygous recessive, and the father is heterozygous.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.

 

Part IV: Lets do some more Punnett Square practice using flower traits. This time, you are looking at co-dominant traits.

If you are experimenting with roses, where red petals and which petals are co-dominate. (Use the letter "R"). Make the following crosses:

  1. Cross red homozygous roses with white homozygous roses.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.
  1. Cross Pink heterozygous roses with Pink heterozygous roses.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.
  1. Cross homozygous recessive roses with Pink roses.
    1. Write the genotype probabilities.

 

    1. Write the phenotype probabilities.
  1. Cross Red homozygous roses with Pink roses.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities

Part V: Now for more practice using traits from people.

Now look lets look at people, using noses. Large noses and small noses are co- dominant. (Use the letter "N"). Make the following crosses:

  1. Mix two large nose parents together.

    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.
  1. Mix two medium nose parents together.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.
  1. Mix a medium nose mom with a large nose dad together.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.
  1. Mix a medium nose mom with a small nose dad together.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.

 

Part VI:

Are you now ready for that sex-linked gene a challenge again?

"Sex-linked traits" come from genes that are located on the X chromosome, and not on the y. (Remembers women are XX and men are Xy). For example, hemophilia is a genetic disorder where a person can not form a blood clot. Hemophilia is a recessive sex-linked trait. Now you write the allele letter as a part of the X chromosome, like this:

 

XH or Xh; y stays blank.

The players: B is not bald, b is bald.

Genotype:

XHXH

XHy

XHXh

Xhy

XhXh

Phenotype:

Not hemopilic female

Not hemopilic male

Not hemopilic "carrier" female

Hemopilic male

Hemopilic female

  1. Cross (mate) a carrier female with a male without hemophilia.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.
  1. Cross a carrier female with a male with hemophilia.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.
  1. Cross a female with hemophilia with a male without hemophilia.
    1. Write the genotype probabilities.

     

    1. Write the phenotype probabilities.
  1. If you’re a guy, which member of your family should you look at to tell if you have hemophilia? Why? (Use a Punnett Square in your answer).