Griffith, Hershey, Chase

Question 1

Frederick Griffith

Answer 1

British medical officer that performed experiments in the late 1920s while trying to develop a vaccine against pneumonia. Dealt with two strains of bacteria: one pathogenic and one nonpathogenic. He heat killed the pathogenic bacteria and mixed the remains with the nonpathogenic bacteria. He studied the mixture and realized that some of the bacteria had become pathogenic. This lead him to the idea of transformation.

http://www.nlm.nih.gov/visibleproofs/media/detailed/vi_a_202.jpg

Question 2

What was Frederick Griffith’s purpose for studying the Streptococcus pneumoniae bacterium?

Answer 2

He was hoping to develop a vaccine against pneumonia

http://i.telegraph.co.uk/multimedia/archive/01899/Streptococcus-pneu_1899711i.jpg

Question 2

Name the experiment described below:

1. Goal was to find which of the two materials that make up a virus actually infect a cell
2. They tagged the protein with a radioactive isotope of sulfur and tagged the DNA with a radioactive isotope of phosphorus
3. They found that the radioactive phosphorus (phage DNA) entered the cell but the protein did not

Answer 2

Hershey and Chase Experiment, 1952

http://bioap.wikispaces.com/file/view/hershey.jpg/130922721/hershey.jpg

Question 2

Name the scientist whose experiment is described below:

1. Dealt with two strains of bacteria: one pathogenic and one nonpathogenic
2. Heat killed the pathogenic bacteria and mixed the remains with the nonpathogenic bacteria and injected the various strains into mice
3. Observed which mice died and which survived after the injections
4. This scientist formed the idea of bacterial transformation

Answer 2

Frederick Griffith, 1928

http://cf067b.medialib.glogster.com/media/18/18a2067f144520eeaec36b9b00d1a5a6ef439d7ad48ae6287a05848430998dd8/sadava-11-1-large-2-1.gif

Question 4

What was the purpose the Hershey and Chase experiment?

Answer 4

Determine which of the two components of a virus actually enters a cell and reprograms it to produce more viruses.

http://upload.wikimedia.org/wikipedia/en/1/1e/Virus_stucture_simple.png

Question 5

Which animals did Frederick Griffith use in his experiment with DNA transformation?

Answer 5

Mice!

https://www.youtube.com/watch?v=MPhLFFAQYbw

Question 6

Which virus and bacteria did Hershey and Chase test in their experiment?

Answer 6

T2 virus E. coli bacteria

http: //fc08.deviantart.net/fs70/f/2011/270/e/e/t2_virus_by_ravihara_weerathunge-d4b3a1y.jpg
http: //foodpoisoningbulletin.com/wp-content/uploads/ecoli-bacteria-green.jpg

Question 7

Transformation

Answer 7

A change in genotype and phenotype due to assimilation of foreign DNA

http://www.bio.davidson.edu/Courses/Molbio/MolStudents/spring2003/Siegenthaler/fig2.gif

Question 8

Which two radioactive isotopes did Hershey and Chase use in their experiment?

Answer 8

Radioactive isotope of sulfur for the proteins

Radioactive isotope of phosphorus for the DNA

Question 9

Why was a radioactive isotope of phosphorus a good choice for the DNA tag?

Answer 9

The atoms of radioactive phosphorus labeled only the DNA and not the protein because all of the phage phosphorus is found in DNA

Question 10

Why was a radioactive isotope of sulfur a good choice for the protein tag?

Answer 10

Proteins contain sulfur while DNA does not. Therefore, the radioactive isotope of sulfur would only mark the protein.