Name ______

Baby Reebops

Congratulations! You and a partner are about to become surrogate parents of a baby reebop! Don’t worry I know you can handle it. But, just like in real-life parenting, you’ll have to do a lot of new learning along the way.

Part I: Analyzing the Parental Chromosomes – Making Gametes!

Now, you’re ready to examine the reebop chromosomes. Lucky for you, reebops have only 18 chromosomes (9 homologous pairs) and each chromosome only carries one gene that codes for one trait. Even luckier, the allele is clearly written on the chromosome!

Take out all of your reebop parents’ chromosomes and arrange them from largest to smallest. Notice the letter on each chromosome. This is the allele, or version of the trait that the chromosome carries. Then, using the table below:

Record the genotype of your reebop’s biological parents.

AND

For each chromosome, list whether the reebop parent is homozygous recessive (dd) meaning homozygous with alleles that require two doses to show trait, or homozygous dominant (DD) meaning homozygous with alleles that require only one does to show trait or heterozygous (HZ). Remember: recessive alleles are represented by lower case letters and dominant alleles are represented by UPPER CASE LETTERS.

Reebop Biological Mother / Reebop Biological Father
Chromosome # / Allele / Allele / (DD)(dd), or
HZ (Dd) / Chromosome # / Allele / Allele / (DD)
(dd), or
HZ (Dd)
1. / 1.
2. / 2.
3. / 3.
4. / 4.
5. / 5.
6. / 6.
7. / 7.
8. / 8.
Sex chromosomes / Sex chromosomes

Gametes (egg or sperm) are haploid and only receive one copy of an allele for each trait. Each gamete produced has a 50% chance of receiving one of the two alleles for any given trait. To determine the genotype of the gamete the biological mother will contribute (egg) and the gamete the biological father will contribute (sperm), you will flip a coin.

Heads = dominant allele (UPPER CASE LETTER)

Tails = recessive allele (lower case letter)

Record the genotype of the egg and sperm for your reebop below. Note that each gamete only carries one allele for each trait.

Reebop Biological Mother’s Egg / Reebop Biological Father’s Sperm
1. / 1.
2. / 2.
3. / 3.
4. / 4.
5. / 5.
6. / 6.
7. / 7.
8. / 8.
Sex chromosome / Sex chromosome

Part II: Fertilization and Embryo Development!

During fertilization, the egg and sperm unite, forming a zygote. Note that the zygote has two copies of each allele. In the chart below:

Record the genotype of your baby reebop.

Determine whether the baby reebop is DD, dd, or HZ (Dd) for each trait.

Then, based on the genotype and the key below, record the phenotype (and sex) of your baby reebop.

Baby Reebop
Genotype / (DD),(dd), or HZ(Dd) / Phenotype
1.
2.
3.
4.
5.
6.
7.
8.
Sex chromosome

Key to Reebop Traits:

AA = 2 antennae

Aa = 1 antenna

aa = 0 antenna

RR = Blue nose

RY = green nose

YY = yellow nose

EE = 2 eyes

Ee = 2 eyes

ee = 3 eyes

TT = curly tail

Tt = curly tail

tt = straight tail

LL = black tail

LW = brown tail

WW = white tail

BB=green legs

Bb=green legs

bb=white legs
DD = 3 body segments

Dd = 3 body segments

dd = 2 body segments

MM = 3 green humps

Mm = 2 green humps

mm = 1 green hump

Now, build your baby reebop with the materials supplied, and place it in the “nursery” along with a card showing the names of the surrogate parents (you and your partner) and the name of your baby reebop.

Part III: Reebop Nursery Analysis

  1. In the space below, record the number of baby reebops that have each of the following traits.

Trait / Phenotype / # / Phenotype / # / Phenotype / #
Antennae
Nose
Eyes
Body segments
Green Humps
Tail structure
Tail color
Leg color
Gender
  1. All of the baby reebops in the nursery were created from gametes from the same two parents. Why aren’t all of the baby reebops identical?
  1. What is the most common phenotype for antennae? Why? (Think about the genotype – phenotype connection.)
  1. What is the most common phenotype for green humps? Why? (Again, think about the genotype – phenotype connection.)
  1. Can you tell the genotype of a baby reebop just by looking at it? Why or why not?
  1. What information would you need to make an accurate prediction about the genotype of a baby reebop?