Chapter 16 - The Molecular Basis Of Inheritance Flashcards
Who performed an experiment using Streptococcus pneumonia that proved DNA could transform bacteria?
Frederick Griffith, in 1928
What were the 2 strains Griffith used?
- S strain - pathogenic
* R strain - non-pathogenic
What are bacteriophages?
“Bacteria-eaters” : viruses that only affect bacteria
Why are viruses simpler than cells?
They are DNA (or RNA) enclosed by a protective coat (protein)
What is a phage composed of?
- protein coat
* encapsulated DNA or RNA
Which phage infects E. coli?
T2
DNA
What did Hershey & Chase’s experiment consist of?
They used radioactive sulphur and phosphorus to trace the fates of protein and DNA of T2 phages that infected bacterial cells.
What results did Hershey and Chase obtain?
When proteins were labelled, radioactivity remained outside the cells. When DNA was labelled, radioactivity was found inside the cells. Bacterial cells with radioactive phage DNA released new phages with some radioactive phosphorus.
Conclusion- Phage DNA entered bacterial cells but phage proteins do not. Hershey & Chase concludes that DNA, not protein, functions as the genetic material of phage 2.
What is Chargaff’s rule?
Adenine => Thymine
Cytosine => Guanine
___ took an X-ray diffraction photo of DNA resulting in the deduction of a double-helical structure of DNA by ____ & ____
- Rosalind Franklin
- J. Watson
- F. Crick
How does the double strand assemble in DNA?
- 1 is assembled in 5’ to 3’
- the other runs anti-parallel, from 3’ to 5’
What links 2 bases of the nucleotide ?
Hydrogen bonds
How many HBs between A & T?
2
How many HBs between C & G?
3
True/False:
At higher temperatures, a species with 4 million G-C and 2 million A-T will live longer than a species with 2 million G-C and 4 million A-T
True