Hershey and chase used radioactive atoms of sulfur

  • No School
  • AA 1
  • 9

This preview shows page 2 - 4 out of 9 pages.

Hershey and Chase used radioactive atoms of sulfur and phosphorus to learn whether proteins or DNA entered cells. Proteins contain sulfur, but not phosphorus. DNA contains phosphorus, but not sulfur. The results of their experiment supported Avery’s conclusion that DNA is the genetic material. Experiment 1 Experiment 2 Hershey-Chase Experiment Result: 35 S did not enter bacterial cells. Conclusion: Protein is not the genetic material. Result: 32 P entered bacterial cells. Conclusion: DNA is the genetic material. 1. First, the scientists grew two batches of bacteriophages. One batch grew in an environment rich in 32 P. The DNA in these viruses therefore contained a great deal of 32 P. The second batch grew in an environment rich in 35 S. The protein in those viruses contained a great deal of 35 S. Each batch of viruses was allowed to infect a separate batch of bacteria. 2. Then, the bacteria and viruses were broken apart in a blender. The scientists spun the mixture in a tool called a centrifuge. This separated the heavier bacteria from the lighter bacteriophage proteins. 3. Finally, the scientists used machines to detect radioactivity from the 32 P and 35 S. They found radioactivity from 32 P, but not from 35 S, in the bacteria. This showed that the DNA of the virus, but not the protein, was transferred to the bacteria. 35 S-labeled protein Bacteriophage Phage proteins 32 P-labeled DNA Phage proteins Bacteria Bacteria READING CHECK 3. Explain How did Avery’s experiments show that DNA is the genetic material? dggcaf_8[dgk]j8 4. Identify Which radioactive atom was found in the infected bacteria? W¤}“}wu¢4h|}/¡}/{ 5. Infer Describe how the results of the Hershey-Chase experiment would have been different if proteins were the genetic material.
Image of page 2
Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Reader 133 DNA, RNA, and Proteins Name Class Date SECTION 1 The Structure of DNA continued READING CHECK 6. Identify Which two scientists determined the structure of DNA? READING CHECK 7. Describe What are the two chemical groups that form the backbone of a DNA strand? dggcaf_8[dgk] 8. Identify Give one difference between purines and pyrimidines. What Does DNA Look Like? By the late 1950s, scientists accepted that genes consisted of DNA. However, they still knew nothing about the DNA’s structure. Several groups set out to discover this structure and the role of DNA in the transfer of genetic information. The research of many scientists helped James Watson and Francis Crick to determine the structure of DNA. The structure of DNA is a double helix . It looks like a spiral staircase made of two parallel, winding strands of linked subunits called nucleotides. Each nucleotide consists of three chemical groups: a phosphate group, a five-carbon sugar molecule, and a nitrogen-containing, or nitrogenous , base. The five-carbon sugar, called deoxyribose, gives DNA its name.
Image of page 3
Image of page 4

You've reached the end of your free preview.

Want to read all 9 pages?

  • Fall '19
  • DNA, Holt, Rinehart

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes
A+ icon
Ask Expert Tutors