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Griffith
Experiment:
Griffith used two strains of bacteria. The R-straing (rough) and the S-strain (smooth). The diffreence between the 2 strains is the S-straing has a smooth coat that protects it. Griffith enjected the R-straingn into a mouse and 3 days later it was still alive. The S-strain was also enjected into a different mouse, 3 days later the mouse had died. For the next step Griffith boiled the S-strain until the protien coat was destroyed. -
Griffith
[Griffith's Experiment:](file:///Users/student/Desktop/342395_Bio-07-01-Griffiths-Experimental-Results.jpg.jpg)Experiment Continued:
After the S-strain coat was destroyed it was then enjected into a mouse, 3 days later it was still alive. For Griffith's last experiment he enjected the S-strain with no protien coat and the R-strain. 3 days later the mouse was dead. Conclusion:
Giffith concluded that something caused the R-strain to turn into the S-strain (with no protien coat) when they're both enjected into a mouse. -
Griffith
Significance:
It showed that there was something going into the R-strain to make it an S-straing with a protien coat. This showed something from S-strain plus R-strain produce a new S-strain (S proved to be donminant. Genetic material (DNA) is the substance.) -
Period: to
History of the Discovery of DNA
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Avery, Mclead, McCarty
[Experiment: ](file:///Users/student/Desktop/FG11_02.JPG)Experiment:
Avery et al first put S-train (no protien coat), R-strain, and an enzyme that kills protien. The mouse 3 days later the mouse died. During the second experiment Avery et al enjected an S-strain (no protien coat), R-strain, and a enzme that kills DNA. 3 days later the mouse was still alive. Conclusion:
Avery et al concluded that DNA holds the genetic information. -
Avery, Macleod, McCarty
Significance:
This proves that the mystery genetic material is not a complex protient, but a simple DNA. This helps lead to the discovery because it's the infromation that's passed on to reproduce. -
Lederberg and Tatum
Conclusion: This proved that the bacteria has to donate a copy of it's genes to the other to produce more bacteria. Just like how humans need to make a copy of their DNA to reproduce.
Significance:He discovered that there was some type of genetic material that get's passed on to reproduced and without that genetic material then reproduction can't occur. If he didn't find out that there is a substance (DNA) that needs to be passed down to reproduce without derformity then no one would've look -
Lederberg and Tatum
looked for a genetic material (DNA). Without this discovery no one would've even known genetic material is needed to reproduced, thus that is was DNA or a protien. -
Lederberg and Tatum
Experement:
Ledergerg added supplements to 2 mutant genes then later saw that more bacteria was produced, that started from bacteria cell dividing many times. Then he put both mutants together (one -MET-BIO the other -PRO -THR) in an enviroment with all 4 supplements (+MET+BIO+PRO+THR). After the two strains had grown together he put them on a plate with no suplements and waited overnight to let them grow. The next morning he saw few bacteria colonies had grown. -
Chargaff
[Discovered:](file:///Users/student/Desktop/chargaffs_rule2.png)Chargaff discovered that the amount of (A) Adenosine is always equal to the amount of (T) Thymine and that the amount of (C) Cytosine is always equal to the amount of (G) Guanine. Conclusion:
Finding A=T and that C=G lead to him discovering A always bonds with T and that C always bonds with G.
Significance:
This discovery help lead to the discovery on how DNA is formed. -
Hershey and Chase
Conclusion:
Because DNA is what was injected into the molecule by the bacteriaphage this proves that DNA is the genetic material. Significance:
This is another way that showed DNA is the genetic material. This answered the question, what is DNA? -
Franklin and Wilkins
[Experiment:](file:///Users/student/Desktop/franklin-typebphoto.jpg)
Franklin and Wilkins took pictures of DNA using X-ray diffraction that produced a picture where the genetic material was blocking the light.
Conclusion:
Franklin's pictures had just one big X on them. Wilkins shared one of Franklinds pictures on the genetic material that Watson and Krick used to model DNA.
Significance:
This was a huge help in finding the structure of DNA. This helps anwer what DNA looks like. -
Hershey and Chase
Experiment:
Hershey and Chase tagged a protien coat (on a bacteriaphage) with radioactive isotope that creates a glow. Later in showed there was no glow in the molecule. This proves the protien was not what was being enjected into the molecule (not the genetic material). The next time they tagged the DNA in a bacteriaphage with the radioactive isotope. Later there was a glow in the molecule. DNA is what moved into the molecule. -
Watson and Crick
[Experiment:](file:///Users/student/Desktop/Image197.gif)Experiment:
Watson and Crick focused on finding the shape of DNA (genetic material). At first they went off on what little information they had. After making a fool of themselves with their first presentaion of what they thought DNA looked like Watson and Crick started "borrowing" information from the scientists also working on DNA (genetic material). -
Watson and Crick
Conclusion:
In conclusion, Watson and Crick "borrowed" everyone else's work and put it all together to figure out what the shape of DNA is. Significance:
Watson and Crick put everyone's information about DNA and put it all together. Which lead to discovering the structure of DNA and the discovery of DNA itself.
