DNA and RNA---Outline

---Hi! Ok, well, finals are coming up and I had nothing better to do with my time, so I decided to write up an overview (is still not finished) of one of my Biology chapters. And I thought you guys might find it interesting since so many of you find my journal entries pointless. That's fine. Just don't be retard-ios about it when I say: "WHAT WHAT! IN THE BUTT!!" etc. etc.
...Don't ask...

Biology Chapter 12 Outline

GRIFFITH

In 1928, a British scientist named Frederick Griffith had two isolated bacterial strains that were slightly different from each other. They were two types of pneumonia bacteria from mice. They both grew well on culture plates, ever though only one of them caused pneumonia.
Disease-causing strains: grew in smooth colonies.
Harmless strains: grew colonies with rough edges.
The mice, when injected with the disease-causing strain, developed pneumonia and died. When injected with the harmless strain, they were fine. These results made Griffith wonder whether or not the smooth colonies excreted poison. To find out if he was correct, he took the disease-causing strain and heated it to kill the bacteria. He then injected the heat-killed bacteria into the mice which survived. This proved that the smooth colonies did not, in fact, release poison.
Griffith then decided to mix the heat-killed bacteria with the living, harmless strain of bacteria and inject the mixture into the mice. The mice developed pneumonia and most died. When he examined the lungs of the mice, he found not the harmless strain of bacteria, but with the disease-causing bacteria. This meant that somehow, the heat-killed strain converted its disease-causing bacteria to the harmless strain. Griffith called this process transformation because one strain had been apparently transformed permanently into another (the disease-causing strain).

AVERY AND DNA

In 1944, a group of scientists was led by Oswald Avery, who decided to repeat Griffith’s work to find which molecule in the heat-killed bacteria was most important for transformation.
They made an extract (juice) from the heat-killed bacteria and then carefully treated the juice with enzymes that destroyed proteins, lipids, carbohydrates and other molecules including RNA. Transformation still occurred. That meant these molecules were not responsible for transformation.
They repeated the experiment, this time using enzymes that would break down DNA. Transformation did not occur when the DNA was destroyed, meaning that DNA was the transforming factor.
-They discovered that DNA stores and transmits the genetic information from one generation to the next.

HERSHEY-CHASE EXPERIMENT
Hershey and Chase conducted their experiments on the T2 phage (bacteriophage), a virus. The phage consists only of a protein shell containing its genetic material. The phage infects a bacterium by attaching to its outer membrane and injecting its genetic material, causing the bacterium's genetic machinery to produce more viruses, leaving its empty shell attached to the bacterium.
For a first experiment, they grew bacteria on culture plates containing Phosphorus-32* and Sulfer-35*.
*- to be used as radioactive markers.
If Sulfer-35 was found in the bacteria, it would mean that the viruses’ protein had been injected into the bacteria. If Phosphorus-32 was found in the bacteria, then DNA had been injected. The scientists mixed the bacteria with the viruses, waited a few moments, and then separated them.
Nearly all the radioactivity turned out to be Phosphorus-32, which meant DNA was the injected genetic material.