3 Major experiments in confirming DNA is the genetic material

http://www.youtube.com/watch?v=qoERVSWKmGk (Bozeman Biology History of DNA) Frederick Griffiths Frederick Griffiths looked at ___________________, which has 2

strains________________ (virulent) and ____________________ (non-virulent).

The mouse ____________ when Smooth (S) live bacteria where injected, unlike when live

___________ (R) were injected. Which of these experiments was the

control?____________________ When S bacteria were heat killed the

mouse____________________, since the bacteria were dead they could not infect the

mouse. Griffiths then mixed heat killed _________________ strain and live Rough (R).

He then injected the mouse which then died. This, Griffith believed was from a

_______________________ moving from the dead Smooth (virulent) to the living

_____________ (non-virulent)

Avery: What did Avery figure out? What 3 molecules did his team isolate that were candidates for the genetic material? Avery‟s team isolated 3 main molecules from heat killed smooth strain. Avery then added

_________________ separately to digest _______, _______, or ______________.

(One enzyme per biological molecule). These digested mixtures were added to Rough live

bacteria and then injected into mice. Avery then observed whether or not they killed the

mice. Avery determined that when ____________ was digested with DNAse (meaning it

was no longer „transforming‟ the _____________ strain) the mice lived. If the isolated

DNA was added without being destroyed by enzymes the mouse died. This meant that Avery

determined that ___________ was the genetic material. Why did scientists think

otherwise?

Image taken from textbook:

Hershey and Chase: Above we learned that Fredrick Griffith discovered a __________________. By the late

1940‟s, scientists knew that eukaryotic chromosomes consisted of two substances: DNA and

protein. There are twenty amino acids and only four bases that make up DNA, so scientists

at the time thought that DNA was too simple to account for all the traits in organisms. In

1952 Alfred Hershey and Martha Chase performed one of the most convincing experiments,

that DNA not protein is the genetic material. They used bacteriophages

(_____________________) (called phages for short). Bacteriophages are actually

____________. Viruses do not have their own machinery to replicate, so they hijack cells

to create more copies of themselves. Hershey and Chase used 2 different

__________________, Sulphur, which was “dyed” red and Phosphorus “dyed”

________. Sulphur was important because it is found in ___________________ but

not_______________. Phosphorus is found in DNA but not in _______________.

The only one that was found to “transfer” was the green dye finally proving that

___________was the „transforming‟ material and was „transferring the genetic code.

http://en.wikipedia.org/wiki/Hershey%E2%80%93Chase_experiment