Published using Google Docs
DNA History WebquestV2.docx
Updated automatically every 5 minutes

DNA History Webquest                         Name ______________________________________

Using the links provided, work your way through the history of the discovery of DNA as genetic material..

1. Friedrich (Fritz) Miescher ( )

        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  ( )

or  ( )  Frederick Griffith’s famous experiment was conducted in 1928.  

What happened when smooth (S) virulent bacteria were injected into mice?  __________________

What happened when the rough (R) bacteria were injected into mice?  _______________________

What happened when heat-killed (S) bacteria were injected into mice? _______________________

What happened when heat-killed S and normal R bacteria were mixed and then injected into mice?


In his experiment, ______________  bacteria plus ______________ bacteria killed mice. Something was transferred into the Type R bacteria; all that the Type S bacteria could have transferred was DNA.  His experiment demonstrated that DNA was the _______________ material.

3. Alfred Hershey and Martha Chase ( )

What is a bacteriophage?

How does a bacteriophage kill a bacteria?

Which radioactive materials did Hershey and Chase use in their experiment? Explain why these radioactive materials were used.

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

4.  Erwin Chargaff    ( )

Watch “Chargaff’s Ratios.”  Chargaff used relative proportions of bases in DNA to come up with his rules for base pairing.

What are 4 sources of DNA that he used?

Adenine (A) pairs with ___________________  and Guanine (G) pairs with ______________________

The bases that are purines are __________________ and ___________________.  They have ___________ carbon-nitrogen rings.

The bases that are pyrimidines are _______________ and ____________________.  They have _______________ carbon-nitrogen rings.

5. Rosalind Franklin   ( )

 Click on Rosalind’s picture to view her biography.

Why might some people say she was robbed of a Nobel Prize?

Watch Franklin’s X-ray diffraction pattern by clicking on the small X-ray diffraction picture.  

What is x-ray crystallography (aka x-ray diffraction) ?

What did Franklin discover about the shape of DNA?  

6.  Linus Pauling   ( )  Watch the animation.

Linus Pauling proposed a structure for DNA that was incorrect.  Describe Paulus’ structure and draw it below.

7.  Maurice Wilkins  ( )  

( )

( )

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

8.  James Watson and Francis Crick   ( )

For what did they receive the Nobel prize?  What year?

Describe the difference between Pauling’s structure and Watson and Crick’s structure.