History of DNA WebQuest

Introduction

While DNA (DeoxyriboNucleic Acid) was discovered in 1868, it wasn't recognized as genetic material until almost a century later. Upon completeing this WebQuest you will have learned about the scientific experiments that lead to the realization of DNA as genetic material and the scientists who conducted those vital tests.

Task

You will visit several websites to learn about the work of eleven scientists who conducted reaserch and ran experiments that lead to the realization of DNA as genetic material. You have quiding questions to answer about each of the following; Friedrich Miescher, Frederick Griffith, Oswald Avery, Alfred Hershey & Martha Chase, Erwin Chargaff, Rosalind Franklin, Linus Pauling, Maurice Wilkins, and James Watson & Francis Crick.

Process

1. Friedrich (Fritz) Miescher

http://www.dnai.org/timeline/index.html

Find Miescher on the timeline and click on the bucket with the Red Cross to watch the animation. In 1869, he extracted a substance from white blood cells that he called nuclein. What do you think he was actually extracting?

2. Frederick Griffith

https://www.dnalc.org/view/16375-Animation-17-A-gene-is-made-of-DNA-.html

Frederick Griffith's famous experiment was conducted in 1928. In his experiment, ______________________ smooth virulent bacteria plus live rough _______________ bacteria killed mice. His experiment demonstrated that DNA was the ______________________ material.

Griffith's Famous Experiment: Transformation

3. Oswald Avery

https://www.dnalc.org/view/16375-Animation-17-A-gene-is-made-of-DNA-.html

In 1944, what did he discover that DNA is responsible for?

4. Alfred Hershey and Martha Chase

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/H/Hershey_Chase.html

In 1952, their experiments showed that ________ is the genetic material instead of ______________.

5. Erwin Chargaff

http://www.dnai.org/timeline/index.html

Watch "Chargaff's Ratios". Chargaff used relative proportions of bases in DNA to come up with his rules for base pairing. What are four sources of DNA that he used?

http://fig.cox.miami.edu/~cmallery/150/gene/chargaff.htm

Adenine (A) pairs with ______________

Guanine (G) pairs with ______________

The bases that are purines include __________ & __________.

The bases that are pyrimidines include __________ & __________.

6. Rosalind Franklin

http://www.dnai.org/timeline/index.html - watch Franklin's X-ray diffraction pattern.

What is X-ray crystallography (a.k.a. X-ray diffraction)?

What did she discover about the shape of DNA?

7. Linus Pauling

http://www.dnai/timeline/index.html - watch the animation.

Linus Pauling propsed a structure for DNA that was incorrect. Describe or draw it.

8. Maurice Wilkins

http://www.nzedge.com/heros/wilkins.html

His research, with the help from _______________, led to the discovery of the DNA molecule structure. This discovery was made by American biologist, _______________, and British physicist, _______________.

9. James Watson and Francis Crick

http://www.dnai.org/timeline/index.html

What did they receive a Nobel Prize for in 1962?

What was the difference between Pauling's structure and the actual structure of DNA?

Evaluation

DNA GAME

http://nobelprize.org/educational_games/medicine/dna_double_helix/

Play the game and record what three organisms you had:

1.

2.

3.

Credits