catChromosomes and Genes - A Simulation

Objective: In this simulation you will examine how alleles are inherited in an organism. The alleles govern the traits for blood type, coat color, and bob tails in cats. In this simulation, the alleles for bobtails and ear shape are located on the same chromosome. The alleles for coat color are located on the sex chromosomes.

Construct Your Parents

In your bag you have 6 chromosomes, represented by pipe cleaners. The white represent autosomes, and the red and blue represent sex chromosomes. Blue for Y, Red for X

You also have beads to represent the alleles for the following traits. You only have 4 white chromosomes for the three traits: blood type, tails, and ears because the tails and ears alleles are located on the same chromosome.

Coat Color
- sex linked, codominant

BB = black
Bb = black & white, spotted
bb = white

Beads used:
Black (B) & white (b)

Blood Type
- multiple allele trait

AA or AO = type A
BB or BO = type B
AB = type AB
OO = type O

Beads used:
Red (A), Blue (B), Clear (O)

Bob Tails
- Single Allele Trait

TT = normal tail
Tt = normal tai
tt = bobtail

Beads used:
Orange (T) & Yellow (t)

Ear Shape:
-Single Allele trait

RR = rounded
Rr = rounded
rr = pointed

Beads used:
Purple (R) & Pink (r)

- alleles located on the same chromosome as bobtail alleles

Parent Genotypes



The dominant alleles TR are on different chromosomes



** The dominant alleles TR are on the same chromosome

Using the pipe cleaners and beads, one partner constructs the male genotype, and the other constructs the female genotype.

Have your teacher check your chromosomes before proceeding! checkbox Instructor Initials
If you got this step wrong, your simulation data will be wrong.

Make Your Predictions

With the parents genotypes given. Predict the phenotypic ratios for each trait, using a punnet square method. Show your work and calculations below

Coat Color Blood Type



Tails & Ears


Run the Simulation

As parents, you will contribute HALF of your genes to the offspring. For each chromosome set, place behind your back and have your partner choose at random which chromosome will be donated to the offspring. One chromosome of each type must be donated from each parent, so that the offspring has a complete set. The offspring will probably not be like either of the parents.

You will repeat this process 12 times to complete the data table below. For each offspring, list the phenotype for each trait.

Coat Color
Blood Type
Offspring 1          
Offspring 2          
Offspring 3          
Offspring 4          
Offspring 5          
Offspring 6          
Offspring 7          
Offspring 8          
Offspring 9          
Offspring 10          
Offspring 11          
Offspring 12          


1. Compare your predicted values with your actual values (from the simulation).

Black Females Spotted Females Black Males White Males Type AB Blood Type A Blood Type B Blood Normal tail, round ears Normal Tail, pointed ears Bobtail, round ears Bobtail, pointed ears
Actual (from simulation)
Predicted (from Punnett)

2. What would you expect the phenotypic ratios to be if the alleles for tail length and ear shape were NOT located on the same chromosome?


3. What chromosomal anomoly would allow for a male to be spotted?