Chemical Analysis Flashcards
What was ultracentrifugation used for and how was it done?
Used for Molecular weight estimation
Extract applied to the top of gradient and put in the machine
The bigger molecules moved farther!
What four methods were used for physical-chemical analysis of the purified transforming substance?
Ultracentrifugation
Electrophoresis
UV absorption spectrophotometry
Chemical analysis
What did electrophoresis determine?
High mobility due to high charge-to-mass ratio of DNA
Phosphate groups have a _______ charge and proteins naturally have _______ charge
Negative
No
What did uv absorption spectroscopy determine?
The absorption spectrum matched the of DNA at 260 nm
Proteins absorb at _____nm due to …
280nm
Due to aromatic amino acids
The chemical analysis found…
A nitrogen to phosphorous ratio of 1.67 protein contamination would raise the ratio
Proteins have little ______ and also contains _____. DNA contains __________.
Phosphorous ; Nitrogen
Both phosphorous and nitrogen
What did early chemical analysis indicate?
That DNA was a monotonous repeat of a four nucleotide sequence of …ACGT-ACGT-ACGT…
If DNA was monotonous then…
DNA could not have been the genetic material
What were two controversies regarding the genetic material?
Whether slight protein contamination in the transforming material was actually the “stuff of genes”
Whether bacterial genes were like that of higher organisms
