Discovery of DNA Flashcards
What was known about DNA before it was proved to be the genetic material
- genes were known to be carried on chromosomes
- chromosomes contain DNA and proteins
- composition of DNA was known (thought too simple to carry genetic material)
- genes were known to be associated with specific characters but the nature of them were unknown
what is the criteria of a molecule that is a carrier of genetic information
ability to store, transmit and maintain genetic information but with a capacity to change
who discovered structure of DNA
watson, crick and franklin
who defined base pairing
chargaff
who found that DNA carries genetic info
avery, macleod, mcCarty
who defined the molecular structure of DNA
Levene
who discovered nucleic acid
miescher
explain fredrick griffith’s experiment
suggested that bacteria are capable of transferring genetic material through a process called transformation.
He used two strains of streptococcus pneumoniae - R and S strains where R is nonvirulent and S is virulent, and heat treated S strain is also non-virulent.
when r strain and heat killed s strain were given to a mouse it died, shows that bacteria can share genetic info
explain the macleod and mccarty experiment
was to explain that DNA was the material causing the bacterial transformation
Heat killed S strain was mixed with enzymes to denature different biomolecules such as RNase, Protease and DNase and then this was added to cultures of R strain. bacterial transformation occurred each time except with the DNase- indicating dna is the genetic material
explain the hershey and chase experiment
this confirmed thay DNA is genetic material.
two tests were carried out including bacteriophages.
one bactieriophage had sulfur in its protein capsule while the other had phosphorus in its DNA core. when each bacteriophage injected their DNA into a bacteria cell, there was no sulfur decected in the cell, while there was phosphorus detected in the cells from the other bacteriophage. proves DNA is the genetic material
