ReeBops

Goal: We are going to look at how the genetic information contained in DNA helps to determine what we look like. In addition, we are going to see how sexual reproduction can lead to a large amount of variation.

You will need the following 2 tables to help figure out what your ReeBop looks like.

Gene Reference Sheet
Chromosome / Alleles / Trait
1 / X or Y / Sex
A or a / Antennae
2 / Q or q / Nose
G or g / Leg color
3 / D or d / Body segment
N or n / Leg number
4 / T or t / Tail
5 / M or m / Hump
6 / E or e / Eye number

Phenotype Reference Sheet

Trait / Possible Genotypes / Phenotype
Sex / XX / Female
XY
/ Male
Antennae / AA, Aa or A- (A-blank) / 2 antennae
Aa / No antennae
Nose / QQ or Qq / Black nose
qq / Blue nose
Leg color /

GG

/ Red legs
Gg / Orange legs
gg / Yellow legs
Body segments / DD or Dd / 3 body segments
dd / 2 body segments
Leg number / NN or Nn / 6 legs
nn / 4 legs
Tail / TT or Tt / Curly tail
tt / Straight tail
Hump / MM or Mm / 2 humps
mm / 3 humps
Eye number / EE or Ee / 2 eyes
ee / 3 eyes

Round 1: Figuring Out What the Mother and Father Look like

For the mother…

  1. Get the “Mother” envelope and dump pink chromosomes on the table so the numbers are facing up.
  2. Match the chromosomes in pairs (They will have the same number) and put the pairs in order.
  3. Start with the #1 chromosomes, and flip them over.
  4. For each of the genes on that chromosomes, record the alleles and the genotype.
  5. Use the Key (1st page) to figure out the phenotype.
  6. Do the same for each of the other chromosome pairs.

Chromosome
# / Trait / Allele from
one chromosome / Allele from other chromosome / Genotype / Phenotype
1 / Sex
Antennae
2 / Nose
Leg color
3 / Body segments
Leg number
4 / Tail
5 / Hump
6 / Eye number
  1. When you have recorded all of the information for the mother, use the space below the table to draw a picture. (You decide what the ReeBop looks like, just make sure that it matches the features described above.)

For the father…

  1. Get the “Father” envelope and dump blue chromosomes on the table so the numbers are facing up.
  2. Follow the same procedure as you used for the mother to record the father’s information.

Chromosome
# / Trait / Allele from
one chromosome / Allele from other chromosome / Genotype / Phenotype
1 / Sex
Antennae
2 / Nose
Leg color
3 / Body segments
Leg number
4 / Tail
5 / Hump
6 / Eye number
  1. When you have recorded all of the information for the father, use the space below the table to draw a picture. (You decide what the ReeBop looks like, just make sure that it matches the features described above.)

Round 2: Let’s Make Some Babies

Today you and your shoulder partner will make 2 new ReeBops from your mother and father.

Mixing the parents…

  1. Pour out the Mother chromosomes and arrange them in pairs with the numbers facing up.
  2. Split the mother chromosomes evenly - each partner takes a pink #1, each partner takes a pink #2, etc.
  3. Now, pour out the Father chromosomes and arrange those in pairs with the number facing up.
  4. Split the father chromosomes evenly – each partner takes a blue #1, each partner takes a blue #2, etc.

What does your baby look like?

  1. Arrange your 6 pairs of chromosomes in order (each pair will have a blue and a pink).
  2. Following the procedure of Day, record the allele, genotype and phenotype.

Chromosome
# / Trait / Allele from
Mother / Allele from Father / Genotype / Phenotype
1 / Sex
Antennae
2 / Nose
Leg color
3 / Body segments
Leg number
4 / Tail
5 / Hump
6 / Eye number

8. Make a drawing of your baby ReeBop. Be sure it includes all the phenotype information above.

ReeBops Data Analysis

In order to understand what happened, we are taking a closer look at a couple of the traits.

Write the class data collected for the frequency of each genotype and phenotype in the space below. Then, use the data to create a pie chart for the frequencies of genotype and phenotype for each trait in the space provided.

Sex / Genotype / XX: ____ / XY: _____
Phenotype / Female: ______/ Male:_____
Sex / # / # / Total / Fraction / % / Fraction / % / Fraction / %
genotype / XX / XY / XX / XY
phenotype / Female / Male / Female / Male
Leg
Color / Genotype / GG:_____ / Gg: ______/ gg: _____
Phenotype / Red Legs: ______/ Orange Legs:______/ Yellow Legs:_____
Leg Color / # / # / # / Total / Fraction / % / Fraction / % / Fraction / %
genotype / GG / Gg / gg / GG / Gg / gg
phenotype / Red / Orange / Yellow / Red / Orange / Yellow
Leg Number / Genotype / NN:_____ Nn:______/ nn: _____
Phenotype / 6 Legs: ______/ 4 Legs:_____
Leg # / # / # / # / Total / Fraction / % / Fraction / % / Fraction / %
genotype / NN / Nn / nn / NN / Nn / nn
phenotype / 6 Legs / 4 legs / 6 legs / 6 Legs % / 4 legs
Hump / Genotype / MM:_____ Mm:______/ mm: _____
Phenotype / 2 humps: ______/ 3 humps:_____
Hump / # / # / # / Total / Fraction / % / Fraction / % / Fraction / %
genotype / MM / Mm / mm / MM / Mm / mm
phenotype / 2 humps / 3 hmps / 2 humps / 2 humps % / 3 humps

Comparison of Genotype and Phenotypes for Various ReeBop Traits

Sex
/ Leg Color
/ Leg Number
/ # of Humps

GENOTYPE
K
E
Y
Sex
/ Leg Color
/ Leg Number
/ # of Humps

PHENOTYPE
K
E
Y

Questions:

  1. Neither of the parents had four legs and yet some of the babies have four legs. Explain how some of the babies could have four legs when neither of their parents had four legs.
  1. Is it possible for two babies with the same phenotype to have different genotypes? Explain why or why not. If you think it is possible, give an example. If you think it is not possible, explain why it isn’t possible.
  1. Is it possible for two babies with the same genotype to have different phenotypes? Explain why or why not. If you think it is possible, give an example. If you think it is not possible, explain why it isn’t possible.
  1. Look at the genetic coding for Leg Color. Explain how Leg Color is different from other traits and why we might call it “co-dominant?”
  1. Just like ReeBops, human males are XY and human females are XX. And, just like ReeBops, the human Y-chromosome is shorter than the X-chromosome (and so has fewer genes, or more blanks). Explain why the short Y-chromosome means there are some traits that most likely show up in males rather than females, but when males have the trait, they received the trait from their mother.

Answer the following questions regarding the pie-charts.

  1. Are there any traits that have 100% the same phenotype in the babies? For that trait, what percentage of the babies has each genotype? Now, look at the genotypes for the parents for that same trait. Can you look at the genotypes of parents to explain why there are NO babies with a certain phenotype?
  1. Pick one pair of genotype/phenotype pie-charts for a single trait and make an observation about the connection between genotypes and phenotypes for that trait.
  1. Look at the genes for Leg Number for the mother and the father. What is the probability that one of their babies would have four legs? Show how you can make a precise theoretical probability of the number of babies that would have four legs.