Bioquest 11

Question 1

Griffith, Frederick

Answer 1

British- studied steptococcus pneumoniae bacteria to develop a vaccine. Used 2 strains (R and S) and did testing on mice. Concluded that heat killed S released hereditary factor that transformed R cells into killer cells (transformation)

Question 2

R strain

Answer 2

grew in rough edged colonies, large colonies, harmless- non disease causing

Question 3

S strain

Answer 3

grew in small, smooth edged colonies. Were virulent (disease causing). Had a capsule/shell around bacteria for protection

Question 4

Griffith’s mouse experiment steps

Answer 4

1) inject R into mouse –> mouse lives
2) inject S into mouse –> mouse dies
3) inject heat killed S into mouse –> mouse lives
4) Inject heat killed S mixed with live R –> mouse dies

Question 5

Avery Oswald

Answer 5

American, wants to know exactly what is the transforming agent (DNA, RNA or Protein). used enzymes to determine which one.

Question 6

Oswald’s experiment

Answer 6

used DN’ase to break down DNA
used RN’ase to break down RNA
used Protease to break down Protein
-concluded that DNA was responsible for transformation in bacteria

Question 7

Hershey/Chase

Answer 7

Alfred Hershey and Martha Chase. Also wanted to know if DNA was the transforming agent. Used E. coli. Found that DNA was the substance that got into E. coli

Question 8

Hershey/Chase experiment steps

Answer 8

1) labeled protein with radioactive sulfur (35S)
2) labeled DNA with radioactive phosphorous (32 P)
- wanted wanted DNA and Protein labeled so they could follow each one
- mixed the labeled phages with E. coli

Question 9

DNA history- watson and crick

Answer 9

England - Cambridge university- James Watson (american) and Francis Crick (british)- relied on other peoples work to discover the structure of DNA
-got 1952 nobel peace prize for DNA structure

Question 10

DNA history- Rosalind Franklin

Answer 10

PhD- worked at king’s college in england. x-ray diffraction- her assistant: maurice wilkins

Question 11

DNA structure

Answer 11

large, heavy molecule; 2 strands; made up of repeating subunits called nucleotides

Question 12

parts of nucleotides

Answer 12

1) 5 carbon sugar: deoxyribose
2) phosphate group: 1 phosphorous, 4 oxygens
3) nitrogenous base: carbon, nitrogen & usually oxygen

Question 13

nitrogenous bases

Answer 13

4 kinds:
2 categories:
purines: Adenine and Guanine
pyrimidines: Thymine and Cytosine
-adenine always pairs with thymine
-purines always pair with pyrimidines
-guanine always pairs with cytosine

Question 14

Erwin Chargaff and Complementary Bases

Answer 14

did chemical analysis of DNA- discovered that the % of A always = the % of T (% of occurrence) and that % of G = % of C; means that bases pair very specifically

• bases are complementary
• large purine always pairs with small pyrimidine
• in DNA replication 1 strand acts as a template for a new strand