Original Author: Unknown

Presented by: Tracy M Harper, Western Technical College

Introduction:

Rebops are marshmallow ‘animals’ that have eight characteristics that are determined by their ‘genetic makeup’. Each trait is represented by both a dominant and recessive trait, which depending on how the genes are inherited, will determine the phenotype of the offspring. Rebop offspring traits are made based the genes they inherit from the parents.

Learner Objectives:

  1. Apply the principles of meiosis and genetic transfer of traits.
  2. Determine traits of an offspring based on genetic information from chromosomes by simulating a model of meiosis.
  3. Relate the genotype to the phenotypic expression of a trait.
  4. Determine the mathematical probability of the genotype and phenotype of offspring produced from a Rebop sire and dam.

Assessment Strategies:
Teacher observation
Lab activity analysis questions

Time Allocation

This lesson plan requires 1 hour of in class lab time, and an additional 1 hour of individual practice time to complete the assignment.

LAB PREPRATATION

MARSHMALLOW MEIOSIS LAB : Rebops!

Materials and Supplies:

Large Marshmallows

Mini Marshmallows, colored

Multi colored push pins

Blue Pipe Cleaners

Toothpicks

Thumbtacks (or different colored toothpicks for the antenna)

Preparation:

  1. Create the eight gene pairs listed including the sex chromosomes.

All eight gene pairs should be cut at different lengths.

Each chromosome should have its partner cut at the same length.

Each parent will have a heterozygous pair of genes, the sire’s genes are blue, and the dam’s genes are red.

Use the following traits:

Physical trait / Genes / Supply
Antenna / Aa / Thumbtacks
Nose / Qq / Colored Mini Marshmallow: pink, orange or yellow
Eyes / Ee / Thumbtacks or push pins
Body Segments / Bb / Large Marshmallows
Humps / Mm / Green Mini Marshmallows
Tail / Tt / Pipe Cleaner
Legs / Ll / Toothpicks
Sex / XX or XY
  1. Make up at least one Rebop parent for example.

  1. Students should work in pairs for this exercise, with each pair building their own Rebop. Each student pair should start with a Sire and Dam Rebop set of chromosomes. Students will select one chromosome from the sire (blue) and one from the dam (red) for each gene pair. This mimics fertilization, where one trait is inherited from each parent, and will result will be a ‘genetic code’ for their Rebop.
  2. Every student will likely end up with a different genetic code for their Rebop. However, in the event that there two identical Rebop babies…they have twins!

Part II

Determining Heritability

  1. Have students find a suitable mate for their Rebop, allowing students to use a Rebop ‘stud’ more than once.
  2. Using the Pearson Square, have students determine the probability of the expression of genetic and physical traits based on their cross.

STUDENT LABORATORY

MARSHMALLOW MEIOSIS

Part I: The Making of a baby Rebop

  1. Select one chromosome from each parent for each trait . You should have two gene’s ( one red, one blue) for each trait.
  2. Using the supplies given and the Decoder Key, construct your own Rebop.
  3. Record the genotype and phenotype of your Rebop.

GENOTYPE / PHENOTYPE
Rebop Decoder Key
AA = one antenna
Aa = two antenna
aa = zero antenna / MM = 3 green humps
Mm = 3 green humps
mm = 2 green humps
QQ = red nose
Qq = orange nose
qq = yellow nose / TT = curly tail
Tt = Curly tail
tt = straight tail
EE = 3 eyes
Ee = 3 eyes
ee = 2 eyes / LL = Blue legs
Ll = Blue legs
ll = red legs
DD = 3 body segments
Dd = 3 body segments
dd = 2 body segments / XX = female
XY = male

STUDENT LABORATORY

MARSHMALLOW MEIOSIS: Rebops!

Part II: Determining Heritability

  1. Determine the sex of your Rebop by selecting a sex chromosome from each parent Rebop.
  2. Select a suitable mate for your Rebop, you may use a sire more than once, but not the dam.
  3. Using a Pearson Square for each trait, determine the probability of both the genotype and phenotype of the offspring.

Antenna

Nose

Eyes

Body Segements

Humps

Tails

Legs

TM HARPER

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