Exam 2-Chapter 10 Flashcards
What did Griffith discover
the principle of transformation
How did Griffith discover principle of transformation
isolated two stands of streptococcus pneumonide
one strand was virulent and had a coat that made colonies appear smooth
the other was non-virulent and did not have the coating
Found that virulent forms would mutate into non-virulent forms and lose the smooth coat
What did Avery, McCloud and McCarty do
showed transforming principle is DNA
How did Avery, McCloud and McCarty do this
used RNases, proteases, and DNases to destroy RNA, Protein, and DNA, respectively, in virulent bacteria
the one with the DNA destroyed was the only one that couldn’t transform
What did Hershey-Chase do
confirmed that DNA is the genetic material
How did Hershey-Chase Experiment work
use Bacteriophage T-2
DNA contained phosphorous, protein contained sulfur
used radioactive isotope labeling to track phosphorus and sulfur
Found that phosphorous was maintained in the progeny but not sulfur
What did Watson and Crick do
discovered the 3D structure of DNA
How did Watson and Crick do it
used existing data from Rosalind Franklin’s molecular models and knowledge of structural chemistry
recognized that an Adenin bonded with thymine and a Cytosine bonded with Guanine
William Ashbury
used X-ray diffraction on DNA but could not get a good picture
Rosalind Franklin
also used X-ray diffraction and got much better results but still could not determine structure
Pyridines
single ring strucutre
Cytosine and Thymine
Purines
double ring structure
Adenine and Guanine
Chargraff’s Rule
amount of A= amount of T
amount of C= amount of G
DNA Helix Structure
Two polynucleotide strands that are complimentary and antiparallel
Phosphodiester linkages join nucleotides at the 5’ phosphate and 3’ OH
The two strands are held together by hydrogen bonds
- A-T has 2 H bonds
- C-G has 3 H bonds
DNA Primary Structure
string of nucleotides joined by phosphodiester linkages
