Hershey–Chase experiment

Hershey shared the 1969 Nobel Prize in Physiology or Medicine with Max Delbrück and Salvador Luria for their "discoveries concerning the genetic structure of viruses".

Phoebus Levene's influential "tetranucleotide hypothesis", which incorrectly proposed that DNA was a repeating set of identical nucleotides, supported this conclusion.

Before that, Oswald Avery, Colin MacLeod, and Maclyn McCarty had shown that DNA led to the transformation of one strain of Streptococcus pneumoniae to another.

It was found that these "ghosts" could adsorb to bacteria that were susceptible to T2, although they contained no DNA and were simply the remains of the original viral capsule.

[1] Hershey and Chase were also able to prove that the DNA from the phage is inserted into the bacteria shortly after the virus attaches to its host.

They determined that a protective protein coat was formed around the bacteriophage, but that the internal DNA is what conferred its ability to produce progeny inside a bacterium.

[citation needed] Hershey and Chase's experiment concluded that little sulfur-containing material entered the bacterial cell.

Furthermore, Watson and Crick suggested that DNA, the genetic material, is responsible for the synthesis of the thousands of proteins found in cells.

They had made this proposal based on the structural similarity that exists between the two macromolecules: both protein and DNA are linear sequences of monomers (amino acids and nucleotides, respectively).

Using X-ray crystallography, the structure of DNA was discovered by James Watson and Francis Crick with the help of previously documented experimental evidence by Maurice Wilkins and Rosalind Franklin.

[9] Knowledge of the structure of DNA led scientists to examine the nature of genetic coding and, in turn, understand the process of protein synthesis.

George Gamow proposed that the genetic code was composed of sequences of three DNA base pairs known as triplets or codons which represent one of the twenty amino acids.

These steps include transcription, RNA splicing, translation, and post-translational modification which are used to control the chemical and structural nature of proteins.