DNA Flashcards
What year did Frederick Griffith do experiments with bacteria in?
1928
What bacteria was used in Griffith’s experiments?
Streptococcus pneumoniae
What is the difference between the two strains of bacteria in Griffith’s experiments?
The smooth strain is virulent and the rough strain is non-virulent. The smooth strain has a polysaccharide coat that protects it from the host’s immune system.
What happened when heat-killed S strain was mixed with the R strain in Griffith’s experiment?
The heat-killed S strain transformed the R strain to make the R strain virulent. The S strain was taken up by the R strain and the mouse used was killed.
How did Avery, McCleod and McCarty conclude that DNA was the transforming principle?
They mixed the strains of bacteria with different enzymes and found that if DNase was use, only R cells remained and no transformation occurred.
Who and in what year found the base ratios?
E. Chargaff in 1949.
When was the DNA diffraction pattern found and by who?
1952 by R. Franklin and M. Milkins, but in 1953 the structure of DNA was found by J. Watson and F. Crick.
What components make up nucleotides?
A 5-carbon pentose sugar, nitrogenous bases and a phosphate group.
What is the sugar in DNA?
2’-deoxy-D-ribose
What is the sugar in RNA?
2’-D-ribose.
What are the differences between purines and pyrimidines?
Purines are larger and are a bicyclic ring rather than a single ring.
What is the diameter of a DNA molecule?
20 angstroms.
What are phosphodiester bonds?
5’ and 3’ links to a pentose sugar.
What are N-glycosidic bonds?
Bonds that join the nitrogenous base to a Carbon-1 pentose in the beta configuration.
What are some essential features of DNA?
Right twisting, double stranded helix, anti-parallel, bases on the inside of the helix, major and minor grooves, complementary base pairing.
