Reproducing a Cootie and the Inheritance of Traits

BIOTECH Project University of Arizona

Reproducing a Cootie and the Inheritance of Traits.

Introduction:

Cooties are an unusual life form that have lived on opposite sides of the Sierra Nevada Mountain range in California, and have not reproduced with each other for over 100 generations. The Cooties from the two regions in the mountain range look very differently. Cooties from the east side of the mountains where the rocks are mostly red sandstones have red bodies. The Cooties from the west side where bluish limestone rocks are found to have blue bodies. We assume that these color differences help them survive in their different environments.

We have observed a total 5 physical characteristics, traits, between the two groups of Cooties:

Body and head color that is either red or blue
Ears that are either wide ear or bow
Eyes that are either purple or surrounded by lashes
Mouths that are either lips or tongues
Feet that are either boots or barefeet

Cooties from the east side of the Sierras always have the following 5traits: Red body color, wide ears, purple eyes, lips and boots. Because they always have these traits, these Cooties are “true breeding” for these traits.
Cooties from the west side of the Sierras consistently have the other 5 traits:Blue body color, bows, lashes, tongue and feet. These Cooties are “true breeding” for these traits.

Recently researchers tried to mate the Cooties from the two different regions and found that they were still able to reproduce. You will investigate what happens to the Cooties offspring’s five traits when they are mated.

If a Cootie that is true breeding for red body color, wide-ear, purple eyes, lips and boots were to mate with a Cootie that is true breeding for red body color, wide-ear, purple eyes, lips and boots, what would you predict their babies would look like?

If a Cootie that is true breeding for blue body color, bow ears, lashes on eyes, tongue and feet were to mate with a Cootie that is true breeding for blue body color, bow ears, lashes on eyes, tongue and feet, what would you predict their babies would look like?

What if a Cootie that is true breeding for red body color, wide-ear, purple eyes, lips, and boots were to mate with a Cootie that is true breeding for blue body color, bow ears, lashes on eyes, tongue and feet, what do their babies look like?

What happened and why do you think this happened? Come up with a hypothesis as to why you got these results and what could you do to test your hypothesis?

We will now take two of the above Cooties and mate them. Remember one of their parents had visible traits of red body color, wide-ear, purple eyes, lips, and boots; the other parent had visible traits of blue body color, bow ears, lashes on eyes, tongue and feet. We lost some of these traits in this generation, what do you think will happen in the next generation if we mate two of these cooties?

To play the Cootie Genetics game, break up into groups of three:

One of you will be the mother
One of you will be the father
The third person will record the offspring reproduction events (the doctor)

You will make 40 offspring, recording the five different traits by random drawing of the ”trait factors” by two individuals (the parents). Record factors in the computer program as was demonstrated in the reproduction and offspring generation yesterday.

We will abbreviate the factors for trait that we see with the capital letter referring to the trait visible in this generation, and the small letter referring to the trait we do not see if this generation. For the factors that represent the five traits the one letter abbreviation that we will use are as follows:

Red body color (R)blue body color (r)

Wide-ear (W)bow (w)

Purple-eye (P)lashes (p)

Lips (L)tongue (l)

Boots (B)feet (b)

The one-letter trait corresponds to one of the colors of the cubes, which you are going to use as the factor that will determine the traits of your offspring. You will be randomly selecting for each of your offspring’s traits Body color trait factors: R=red, r=blue; Ear trait factors: W=white, w=black; Eye trait factors: P= purple, y=yellow; Mouth trait factors: L=Lime green, l= orange; Feet trait factors B=Brown, b=green.

To make the offspring you need to find out what traits it will have. It turns out that both parents start out with factors for both red and blue body color, they should have the ability to give either of these factors to their offspring. As a parent you have a cup with an equal number of red and blue factors, you will randomly pick the factors from the cup to give to your offspring.

To make the first offspring each parent will:

Reach into cup 1 and pull out the factor for body color (either a red or a blue cube).
The “doctor” will record which body color factors the offspring received from the parents.
Reach into cup 2 and pull out the factor for auditory appendage (either a white or a black cube).
The “doctor” will record the auditory appendage factors the offspring received from the parents.
Reach into cup 3 and pull out the factors for ocular appendage (either a purple or a yellow cube).
The “doctor” will record which ocular appendage factors the offspring received from the parents.
Reach into cup 4 and pull out the factors for vocal appendage (either a lime green or an orange cube).
The “doctor” will record which vocal appendage factors the offspring received from the parents.
Reach into cup 5 and pull out the factors for motile appendage (either a brown or a green cube).
The “doctor” will record which motile appendage factors the offspring received from the parents.

Once the first offspring is completed, check out your baby, what traits does it have? Same as Mom and Dad? Different? Any of the grandparent’s traits show up? Do the same thing to make the second offspring, then the third and so on. The key is to keep it random, so don’t look in the cup and try to get a specific color cube.

Analysis of Cootie Genetics

Let’s review what we have learned about the inheritance of traits by Cooties:

Recall the original Cooties were either true breeding for red body, wide-ear, purple-eye, lips and boots or true breeding for blue body, bow, lashes, tongue and feet

True breeding means that if two Cooties with red body, wide-ear, purple-eye, lips and boots mate, they will only have babies with red body, wide-ear, purple-eye, lips and boots. Iftwo Cooties with blue body, bow, lashes, tongue and feet mate, they will only have babies with blue body, bow, lashes, tongue and feet.

We discovered that a Cootie with red body, wide-ear, purple-eye, lips and boots mates with a Cootie Cooties with blue body, bow, lashes, tongue and feet, all of the offspring look like this:

Red body, Wide-eared, Purple eyes, with Lips and Boots. These babies looked just like mom and had nothing of dad….What happened to Dad’s traits?

We then took two of those Cooties and mated them to see what the offspring looked like:

How many different Cooties did you have (look at the traits)?

How many Cooties had traits that you did not see in the parents?

How many of your Cooties had the same factors as the parents (look at the factors recorded by the doctor) how many Cooties had factors that were different from the parents?

Did the Grandfather’s traits reemerge?

Using the data you recorded in the Cootie offspring file to fill in the following:

Total # of / Total # of / Total # of / Total # of / Total # of / Total # of
RR / Rr / rR / rr / Red / blue
WW / Ww / wW / ww / Wide-ear / bow
PP / Pp / pP / pp / Purple-eye / lashes
LL / Ll / lL / ll / Lips / tongue
BB / Bb / bB / bb / Boots / feet

Recall the factors correspond to the following cubes: R=Red & r=blue, W=White& w=black, P=Purple & p=yellow, L=Lime-green & l=orange, and B=Brown & b=green.

Look at each trait individually and determine the percentage of Cooties for each trait.:

How many red Cooties were there compared to blue, how many of your Cooties had wide-ears and how may bows, etc?

Do you see a trend? Does one trait appear more often than the other? If yes, why do you think this is the case?

Are both grandparents traits represented in the Cootie offspring of your reproductions? If yes, are they represented equally? Why do you think you had the number of offspring with each represented trait (Red versus blue, purple eye versus lashes, wide ear versus bow, etc)

We know what factors were involved in the representation of each of the traits for all of your Cootie offspring. Each parent had two possible factors that they could offer each of their offspring, however they could only give them one. For example both mom and dad have the R trait factor (for the red cube) and the r trait factor (for the blue cube), however each can only give one of these trait factors to their child.

What are the four possible trait factor representations that Mom and Dad could give their child for body color (represent Mom first)?

From your data, at what ratio are the four possible factor combinations represented in your Cootie offspring?

What can you say about this ratio?

How do the ratios for the trait factor combinations compare to the ratio for your traits?

What conclusions can you make from your data?