Case File: 1007“Who Killed Yanni the Yeast?”

The Victim

Yanni “The Yeast” Yarkow

Earned his nickname by building 5000 factories that produce bread yeast throughout the United States of America

Married to Yasmina Yarkow

Location: Found in the library, holding a glass.

Cause of Death: Suspected poison

The Victim

The Crime Scene

The Crime Scene

At the scene, three unknown compounds were found next to the victim

- Compound A

- Compound B

- Compound C

It is your job to identify these compounds

How to identify the unknown compounds

• We will use yeast as a model system to test the compounds

• Each group will be assigned a compound (A, B or C) to test– Perform a dose response with

your compound and compare to

a control (no compound)

– Compare your dose response

to known chemicals

If yeast are healthy, they will produce a great deal of CO2

The Ziploc baggie will fill up with C02

Q. What is CO2?

Yeast + water + sugar + O2 CO2 + alcohol

What if the yeast are not healthy because something toxic has been added?

Q. Will the baggie fill up as much?

Yeast as a model system

Hei

ght o

f Z

iplo

c B

ag(c

enti

met

ers)

Dose of Compound(Teaspoon)

Which compound is the most toxic? Hint: If it is toxic, would the yeast produce more or less C02?

Which compound is the least toxic?

1.

2.

3.

Making a dose response curveDose response curves are used to determine how much of a compound is toxic

Example: When you take Tylenol, you only take two at a time. If you take more, they can be toxic and lead to an overdose, making you very sick.

Instructions

Control

High(1 teaspoon)

Medium(1/2 teaspoon)

Low(1/4 teaspoon)

Label 4 plastic bags as shown – put your initials on each bag!

To ALL bags, add:-1 ½ teaspoons yeast-1 ½ teaspoons sugar

Add either Compound A, B or C to the three bags labeled “High”, “Medium”, or “Low” following the directions

Add 2 tablespoons of warm water

InstructionsPlace your bags on the heating tables

Things to think about

What happens if the water was too hot?

What if the water was too cold?

Why do we need controls?

+ +

Case File: 1007“The Murder of Yanni the Yeast”

The Suspects

72097Corvallis, OR

Yasmina Yarkow

Yasmina Yarkow

Occupation: Jewelry designer

Relationship to the victim: Wife

Potential motive: Yasmina wanted to open her own jewelry design business, but her husband refused to lend her the money she would need to buy materials

Found at the Crime Scene:1 earring, belonging to Yasmina Yarkow

72098Corvallis, OR

Yardley Tohilo

Yardley Tohilo

Occupation: Owns his own bakery, Tohilo Breads

Relationship to the victim: Has baked for the Yakow family for 20 years, using yeast provided by Yanni. His is the only bakery allowed to use Yakow Yeast. He is famous for his Tohilo loaf; a loaf consisting of only yeast, flour, salt and powdered milk

Potential motive: A new bakery has opened down the street, and Yanni has agreed to sell them his yeast.

72099Corvallis, OR

Yvonne Scherz

Yvonne Scherz

Occupation: Owner; Scherz Cleaning Co.

Relationship to the victim: Distant cousin of Yasmina Yarkow

Potential motive: A year ago, was hired by Yanni’s company to clean the floors of his factory. Yanni was dissatisfied when his floors did not sparkle as promise, and sued. She is in danger of losing her cleaning company.

“Floors so clean they sparkle!” That’s the Yvonne Scherz promise!

Scherz Cleaning Co.The only cleaning company authorized to use a top-secret cleaning compound!

The Poison

Powdered milk

Cleaning compound

Salt

Which is the most toxic?

• The most toxic compound is assumed to be the one that killed Yanni the Yeast– To confirm this, a police laboratory tested the

compound that Yanni ingested right before he died

Results from the Police LaboratoryThe unknown substance found to have poisoned Yanni

Yarkow was identified as the top secret cleaning compound.

72099Corvallis, OR

Yvonne Scherz

Yanni was suing her company.

She couldn’t pay the legal bills, and was about to lose her business. She thought that if Yanni was gone, the civil suit against her would go away, and she could keep her business.