February 2013 Teacher's Guide for Sniffing Out Cancer Table of Contents



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February 2013 Teacher's Guide for
Sniffing Out Cancer
Table of Contents



About the Guide 2

Student Questions 3

Answers to Student Questions 4

Anticipation Guide 5

Reading Strategies 6

Background Information 8

Connections to Chemistry Concepts 15

Possible Student Misconceptions 16

Anticipating Student Questions 16

In-class Activities 18

Out-of-class Activities and Projects 19

References 19

Web sites for Additional Information 20

About the Guide

Teacher’s Guide editors William Bleam, Donald McKinney, Ronald Tempest, and Erica K. Jacobsen created the Teacher’s Guide article material. E-mail: bbleam@verizon.net


Susan Cooper prepared the anticipation and reading guides.
Patrice Pages, ChemMatters editor, coordinated production and prepared the Microsoft Word and PDF versions of the Teacher’s Guide. E-mail: chemmatters@acs.org

Articles from past issues of ChemMatters can be accessed from a CD that is available from the American Chemical Society for $30. The CD contains all ChemMatters issues from February 1983 to April 2008.

The ChemMatters CD includes an Index that covers all issues from February 1983 to April 2008.
The ChemMatters CD can be purchased by calling 1-800-227-5558.
Purchase information can be found online at www.acs.org/chemmatters

Student Questions


    1. What is a Volatile Organic Compound (VOC)?

    2. For people with tumors, what body products can carry or contain VOCs?

    3. Volatility of an organic compound depends on its vapor pressure. What is meant by vapor pressure?

    4. Describe the chemical properties of reactive oxygen species
      and how they are related to cancer.

    5. What is the relationship between VOCs and reactive oxygen species?

    6. Give two advantages when choosing dogs over chemical instrumentation for cancer detection?

    7. What types of cancer are dogs capable of detecting?

    8. What two biological products of the body are sniffed by dogs in detecting cancer?



Answers to Student Questions


  1. What is a Volatile Organic Compound (VOC)?

A volatile organic compound is a molecule that evaporates or sublimates from a liquid or solid phase of the same substance.

  1. For people with tumors, what body products can carry or contain VOCs?

Some of the body products containing VOCs include exhaled breath, urine, and stool, among others.
  1. Volatility of an organic compound depends on its vapor pressure. What is meant by vapor pressure?


Vapor pressure is the pressure at which vaporized molecules reach equilibrium with the solid or liquid phase of the same substance in a closed system.”

  1. Describe the chemical properties of reactive oxygen species
    and how they are related to cancer.

Reactive oxygen species are molecules with unpaired valence electrons that make them highly reactive with surrounding biological materials. If reactive oxygen species are in excess, perhaps because of a deficiency of antioxidant molecules that keep reactive oxygen species in check, then they can damage DNA and healthy cell tissue. This damaging process is known as oxidative stress and is known to be a precursor of cancer.

  1. What is the relationship between VOCs and reactive oxygen species?

Under oxidative stress as outlined in answer #4, “reactive oxygen species oxidize fats in cell membranes, resulting in increased emissions of VOCs ..”. Dozens of specific VOCs have been linked to various types of cancer. Tumors produce changes in not just one type of VOC, but many.

  1. Give two advantages when choosing dogs over chemical instrumentation for cancer detection?

A dog’s nose is a highly efficient chemical sensor, ready-made to sniff cancer VOCs. Second, a dog can detect a cancer through smelling VOCs without needing to know the specific chemical or chemicals present in the vapor. A chemical instrument can only be designed when a specific chemical to be detected is known.

  1. What types of cancer are dogs capable of detecting?

Dogs that are trained can detect skin, breast, lung, prostate, colon, bladder, and ovarian cancer.


  1. What two biological products of the body are sniffed by dogs in detecting cancer?

The two biological products sniffed for cancer-produced VOCs are urine and exhaled air.

Anticipation Guide


Anticipation guides help engage students by activating prior knowledge and stimulating student interest before reading. If class time permits, discuss students’ responses to each statement before reading each article. As they read, students should look for evidence supporting or refuting their initial responses.
Directions: Before reading, in the first column, write “A” or “D” indicating your agreement or disagreement with each statement. As you read, compare your opinions with information from the article. In the space under each statement, cite information from the article that supports or refutes your original ideas.


Me

Text

Statement







  1. A report of a dog alerting his owner to a malignant melanoma was first published in 2002.







  1. Vapor pressure depends on intermolecular forces.






  1. Cancerous cells produce different concentrations of volatile organic compounds (VOCs) than healthy cells do.








  1. A dog’s sense of smell is up to 100,000 times better than a human’s sense of smell.







  1. Cigarette smoke interferes with a dog’s ability to detect lung cancer in a patient’s breath.







  1. Researchers need to know what chemical they are looking for before they can train dogs to detect cancer-related smells.







  1. Artificial noses are being developed that will eventually take over the work of dogs in detecting cancer in human patients.







  1. All VOCs in our environment are harmful to human beings.



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