1What are nucleotides made up of?
deoxyribose sugar, base, and phosphate
2What bonds are in DNA?
Phosophodiester for backbone and hydrogen bonds for nucleotides
3Summarize the methods that located DNA in chromosomes
F. Meischer (1869) extracted "nuclein" which was DNA
Staining in 1923 showed DNA localized in chromosomes
4What is transformation?
The ability to change genetic characteristics
5Bacteria Transformation with Strep. R vs S. Conclusion of Experiment
Griffith (1928) two different strains of strep - smooth and rough injected into rats
Smooth was severe response and rough was mild/no response
R could be transfromed to S by heat killed S cells
6Explain how Avery and his colleagues demonstrated bacterial transformation
- growing R-form bacteria in medium in the presence of components from dead S forms
- used enzymes that degraded RNA, protein, or polysaccharide which had no effect on the transforming principle, but an enzyme that degrades DNA destroyed activity completely
7 explain the significance of this Avery's experiment
DNA was the transforming principle
8What are bacteriophages?
viruses that infect bacteria
9Describe the blender experiments of Hershey and Chase
Phages labeled with radioactive DNA or protein based on which elements are incorporated into each (phosphorus versus sulfur) were centrifuged out of phageinfected bacteria
10What happened during the Hershey-Chase experiments?
Infected bacteriophages with radioactive phosphorus was recovered in host/cell
ones with radioactive sulfur was recovered in ghosts
11What was the conclusion for the blender experiements?
Phages confirmed DNA was the transforming principle.
12X-Ray deffraction showed....
Double helix structure
13What are the key features of the Watson-Crick model for DNA structure?
- Strands are antiparallel
- Sugar – phosphate backbone on the outside
- Base pairs in the middle
- Two chains held together by H bonds between A-T and G-C base pairs
14Z-form DNA
forms left-handed helix and has an irregular backbone: observed in vitro but role unkown
15How does DNA store complex instructions?
sequence of its bases
16two ways in which the information in DNA may be accessed by proteins
- unwound DNA during synthesis of DNA or RNA
- DNA binding proteins that regulate gene expression