14. DNA Synthesis

The Hershey-Chase Experiment

Hershey and Chase Experiment (2016) IB Biology

 No. This is an attractive attribute of viruses and bacteria, but there is a better answer. 

 They typically have relatively small genomes. 

 Their chromosomes have a simpler structure. 

 All of the listed responses are correct. 

Think about all the issues involved in choosing an experimental model.

Which of the following considerations was/were important in the choice of viruses and bacteria for early experiments on DNA?

Describe the general function of the shoot and the general function of the root system. Which tissues are continuous throughout these two systems? Suggest a hypothesis to explain why the shoot and root systems of different species are so variable in size and shape.

Animation: The Hershey-Chase Experiment

The Hershey and Chase Experiment | Discovery of DNA as the genetic material

 Amino acids because of all the ways they can join together 

 No. Amino acids are the monomers that make up proteins. They are not macromolecules, and biologists realized that only macromolecules are large and complex enough to serve as the genetic material. 

 Carbohydrates because they are found in abundance in all organisms 

 No. Carbohydrates were not seriously considered to be the genetic molecules. 

 Sterols because of the different variations on their ring structure 

 No. Lipids were not seriously considered to be the genetic molecules. 

 Nucleoside triphosphates because of the ability to add and remove phosphate groups 

 No. Nucleotide triphosphates, such as ATP and the monomers that are used to build nucleic acids, are not large or diverse enough to encode genetic information. 

 Proteins because they were thought to be the only molecule with both the variety and specificity of function to account for the array of heritable traits observed 

What type of macromolecule was thought to be the most diverse and flexible?

Until Hershey and Chase showed that DNA was the genetic molecule of the phages they studied, what class of molecules was considered the best candidate for carrying genetic information and why?

 No. This was already known before the experiment was carried out. 

 No. This was already known and in any case was not shown by the experiment. 

 the genetic material of the phage is protein 

 No. In fact, the experiment demonstrated that this is not the case. 

 No. This was already known. The experiment here addressed whether the genetic material is present in the DNA or the protein component of chromosomes. 

 the genetic material of the phage is DNA 

This experiment was performed by Hershey and Chase in 1952 as part of the search for the molecule of inheritance.

In an important experiment, a radioactively labeled bacteriophage was allowed to infect bacteria. In a first trial, the phage contained radioactive DNA, and radioactivity was detected inside the bacteria. Next, phage-containing radioactive protein was used, and the radioactivity was not detected inside the bacteria. These experiments led to the conclusion that __________.

Bacteriophages

DNA contains sulfur, whereas protein does not.

DNA contains phosphorus, whereas protein does not.

DNA contains nitrogen, whereas protein does not.

DNA contains purines, whereas protein includes pyrimidines.

Which of the following facts did Hershey and Chase make use of in trying to determine whether DNA or protein is the genetic material?

Hershey and Chase set out to determine what molecule served as the unit of inheritance. Which molecular component of the T2 virus actually ended up inside the cell?

Hershey and Chase Experiment-Finding the genetic material (T2 bacteriophage)

Radioactive labeled protein was found in the bacteria.

Radioactive labeled DNA was found in the bacteria.

DNA was labeled with radioactive phosphorus.

Protein was labeled with radioactive sulfur.

Radioactive labeled protein was found outside of the bacteria.

Choose the incorrect statement about the results of the Hershey-Chase Experiment.

7.1 Analysis of Results of the Hershey and Chase Experiment

Hershey and Chase Experiment: DNA is the Molecule of Heredity

 No. Viral protein does not contain the information for the production of more viral protein. 

 No. However, this answer is partially correct. 

 a mixture of the DNA and proteins of both phages 

 No. Only the DNA and protein of the phage whose genetic material was used would be produced. 

 No. This would be true only if protein were the genetic material. 

Consider the famous Hershey and Chase experiment.

A scientist assembles a bacteriophage with the protein coat of phage T2 and the DNA of phage T4. If this composite phage were allowed to infect a bacterium, the phages produced in the host cell would have __________.

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1. Introduction to Biology

2. Chemistry

3. Water

4. Biomolecules

5. Cell Components

6. The Membrane

7. Energy and Metabolism

8. Respiration

9. Photosynthesis

10. Cell Signaling

11. Cell Division

12. Meiosis

13. Mendelian Genetics

15. Gene Expression

16. Regulation of Expression

17. Viruses

18. Biotechnology

19. Genomics

20. Development

21. Evolution by Natural Selection

22. Evolution of Populations

23. Speciation

24. History of Life on Earth

25. Phylogeny

26. Prokaryotes

27. Protists

28. Plants

29. Fungi

30. Overview of Animals

31. Invertebrates

32. Vertebrates

33. Plant Anatomy