The Hershey-Chase experiments were a series of experiments conducted in 1952 by Alfred Hershey and Martha Chase, confirming that DNA was the genetic material, which had first been demonstrated in the 1944 Avery-MacLeod-McCarty experiment. While DNA had been known to biologists since 1869, most assumed at the time that proteins carried the information for inheritance.
Hershey and Chase conducted their experiments on the T2 phage, a virus whose structure had recently been shown by electron microscopy.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.Structural overview of T2 phage
In a first experiment, they labeled the DNA of phages with radioactive Phosphorus-32 (the element phosphorus is present in DNA but not present in any of the 20 amino acids from which proteins are made). They allowed the phages to infect E. coli, then removed the protein shells from the infected cells with a blender and separated the cells and viral coats by using a centrifuge. They found that the radioactive tracer was visible only in the pellet of bacterial cells and not in the supernatant containing the protein shells.
In a second experiment, they labeled the phages with radioactive Sulfur-35 (Sulfur is present in the amino acids cysteine and methionine, but not in DNA). After separation, the radioactive tracer then was found in the protein shells, but not in the infected bacteria, supporting the hypothesis that the genetic material which infects the bacteria is DNA.
Hershey shared the 1969 Nobel Prize in Physiology or Medicine for his "discoveries concerning the genetic structure of viruses."
Hershey and Chase found that DNA was the genetic material.
I just had Biology Homework on them. :)
how ironic?.. well have fun learning about them.. not.
kjkj.kj
Bacteriophage
controlled results stay the same in an experiment
The results of an experiment are called your data.
DNA controls heredity, not proteins.
bacteriophages
An experiment in which the results are repeatable....apex
The outcome of an experiment is a "conclusion", the interpretation of the results compared with the expected results and the goal of the experiment.
A disadvantage of a vitro experiment is that the results can be misleading.
The results of a science experiment do not have to match the original hypothesis. Indeed, the results collected in an experiment may be completely different to those that the scientist predicted.
Observations and measurements made during an experiment are called the data.
Analyze the experiment to decide whether the results were flawed.