DNA as Genetic Material Hershey And Chase Experiment: Overview and Diagram

History Of Hershey And Chase Experiment

The discovery of DNA as the genetic material was a very momentous breakthrough in molecular biology. Up to that time, the scientific world was in contention as to whether proteins or DNA were the bearers of genetic information. The Hershey and Chase experiment delivered an answer to this question, providing final evidence showing that DNA is the genetic material responsible for the process of heredity. Alfred Hershey and Martha Chase proved that it is DNA and not proteins which represent the agent that carries genetic information into bacterial cells, thus laying the foundation of molecular biology.

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This Story also Contains

1. History Of Hershey And Chase Experiment
2. The Hershey And Chase Experiment
3. Results Of The Experiment
4. Conclusion Of The Experiment
5. Recommended video for The Hershey And Chase Experiment
6. Implications Of The Experiment

The Hershey And Chase Experiment

Objective

The Hershey and Chase experiment aimed at determining if DNA or rather protein is the genetic material that viruses use to replicate inside the bacteria. Their preliminary hypothesis was that one of the two that were injected into bacteria would be given, directing the production of new viral particles.

Materials And Methods

• Bacteriophages: These are viruses that infect bacteria, in particular the T2 phage used in this experiment. Since these bacteriophages just possess a protein coat with DNA, it greatly served the experiment in determining which component is holding the genetic information.

• E. coli Bacteria: Another common bacterium used was yet another host in this experiment for the T2 phage. This is so because the explanation of the transfer of genetic material had to be demonstrated as a result of the relation of the phage with E. coli.

Isotopes Used

• Phosphorus-32 (P-32): DNA - These bacteriophages are then allowed to infect the bacteria, and the radioactive DNA is labelled with phosphorus 32, as DNA is known to be rich in phosphorus.

• Sulfur-35 (S-35): The phages are allowed to infect the bacteria following the labelling step to enable the radioactive proteins coat of the phages to be labelled with Sulphur 35 because neither the proteins nor the sulfur are involved in the DNA material.

• Bacteriophages were cultured in a supplemented culture medium made with radioactive phosphorus (P-32). In this way, the obtained phages were therefore marked with radioactive DNA.

Labelling Of Proteins With Sulfur-35:

The remaining bacteriophages were cultured in a culture medium supplemented with radioactive sulphur (S-35), resulting in radioactive proteins on the coat of the bacteriophage.

Infection Of E. Coli With Labeled Bacteriophages:

• E. coli cultures were infected with either P-32 or S-35 labelled phages to label the components entering the bacterial cells.

Breakage And Centrifugation:

• After the infection was allowed, the mixture was agitated to separate phage coats from bacterial cells.

• Then, centrifuging followed to separate the heavier bacterial cells from the lighter phage coats.

Radioactivity Measurements:

• Radioactivity was measured in the bacterial pellet and the supernatant, the fluid containing the phage coats, to determine the location of the P-32 and S-35 isotopes.

Results Of The Experiment

• The P-32 labelled DNA was within the E. coli cells, and the S-35 labelled protein was out of the cells in the supernatant.

• It can, therefore be deduced that only the DNA entered the bacterial cells and was responsible for directing the synthesis of new phages.

Conclusion Of The Experiment

The conclusion from the Hershey and Chase experiment was the final and clear evidence to show that DNA was indeed the genetic material. It was the DNA, not that protein, of the bacteriophage that had been injected into the bacteria and had specified the assembly of a new generation of infectious viral particles. This experiment has shown the way to understand the molecular basis of heredity.

Recommended video for The Hershey And Chase Experiment

Implications Of The Experiment

• The Hershey and Chase experiment was very influential in molecular biology, providing concrete evidence that DNA is the genetic material and that the discovery of its structure and function was significant and relevant for later scientific study.

• This experiment resulted in the determination of the DNA double helix structure by James Watson and Francis Crick in the year 1953. The perception that DNA is the genetic material also led to huge advancements in genetic engineering, biotechnology, and medical research.

• The realisation of the fact that DNA is the molecule of heredity was crucial to the follow-up influence on molecular genetics, the science that studies how the information encoded in genes is stored, replicated, and expressed.

• This discovery has also contributed towards future progress in techniques such as the sequencing of DNA, polymerase chain reaction (PCR), and genetic cloning, which, at present, have a major stake in biological research and medicine.

Conclusion

The Hershey and Chase experiment yielded irreparable proof that DNA and not some protein is the material responsible for the genetic nature of heredity and caused a complete turn of events in molecular biology conception. It would be the foundation from which the structure and function of DNA would become known and have huge impacts from that time moving forward on the study of genetics, biotechnology, and medicine. These bottom lines established by this experiment even to this day still keep propelling the growth in genetic engineering, genomics, and personalised medicine—an outcome from the fundamental basis this formed in contemporary research and applications.