The first year of the new decade, 1970 a discovery was already made. Hamilton Smith made the discovery of the first restriction enzymes. Smith was working with the bacterium Haemohphilus influenzae. Smith demonstration of his discovery was that the bacterium cuts the DNA from the virus ‘phage P22’ at specific places and also into somewhat equal sized portions. The analogy to describe these restriction enzymes is as follows. The enzymes are scissors to the DNA. They are a necessity to dissembling and reassembling of DNA molecules. This discovery also is a help in launching a revolution in recombinant DNA.
For a decent amount of time, it was thought that the genetic information only moves in one direction, from DNA to RNA and then to a protein. Yet another idea was proven to be false. Howard Temin made the discovery in 1970 that changed the idea, and amazingly, so did David Baltimore. It was discovered that certain viruses, like the Rous sarcoma virus or RSV transmit RNA instead of DNA to the host cell. So that instead of the DNA being inserted into the host cell, the RSV’s RNA acts as the template for the host cell to make the viral DNA, this process is called reverse transcription. The enzymes that made reverse transcription were also discovered. Named simply reverse transcriptase, the enzyme proved to be crucial to the study of molecular biology because of it’s ability to make complementary DNA copies of messenger RNA.
Also in 1970, the first oncogene was discovered. Oncogenes are genes that cause cancer in the organism. The Rous sarcoma virus was the subject of study once again. Peter Duesberg and Peter Vogt are responsible for the discovery of the cancer causing gene sequence. The virus infects chickens and causes them to develop cancer. The gene responsible for it was soon after isolated and named the gene src. Later other researchers made the surprising discovery that the very same gene already exists in other organisms, including humans. The oncogenes that are inside of us are a normal part of what makes up our genetic make-up. They have been the subject of a lot of cancer research and what causes these genes to become active inside our bodies, so this was another very important discovery.
The next year, 1971, the first DNA sequence was made. Even though the genetic code had been cracked more than five years ago, researchers still haven’t developed an easy way to read DNA sequences. It was Ray Wu and Ellen Taylor that made the successfully read the sequence of an unpaired set of nucleotides at two ends of the DNA molecule that came from the virus bacteriophage lambda. Wu and Taylor used various enzymes as methods of cutting repairing the sequence from the rest of the DNA chain. The two could read the twelve nulceotides at each of the ends as ‘GGGCGGCGACCT’. This was another step closer to being to fully sequence genes.
In 1973, the precursor to the Human Genome Project took place. Frank H. Ruddle was interested in finding genes on the chromosomes of humans. His first workshop was responsible for finding one hundred genes. Then multiple later workshops also found ~2000 genes on the chromosomes. All the data discovered from these projects were published publically, setting the scene for the Human Genome Project, which started in 1989.
To help the efforts of genomic development, Ed Southern developed a new and quick way to find individual genes in 1973. For a long time Southern was working with finding genes by studying pieces of DNA put onto a special gel, this method did not prove to be effective, so naturally Southern set out to find a better method. The result of his studies was a new process that is as follows: First he started by getting gel with the DNA on it and soaking it. He then used paper towel as a medium to draw out the DNA, trapping it on a fine membrane filter. The next step in his process was using a radioactively labeled piece of DNA or RNA to poke around for it’s twin gene, and then was located using a photographic film. This method was nicknamed ‘Southern blotting’ This striking discovery ended up being a very important piece to the success of later discoveries, one of the most notable being DNA fingerprinting.
In 1975 the Asilomar Conference was held. Around 140 biologists, lawyers, and doctors were present and debated the legality, ethicalness, and the bio-safety of the research of recombinant DNA. A year prior to this conference a committee that was a part of the US National Academy of Sciences said that all researches of that type were to be stopped and that the conference was to be held. The verdict that they reached was to continue under new conditions that ensured the containment of all genetically modified organisms.
Then in 1977 Richard Roberts and Philip Sharp made the discovery of split genes. These genes were the DNA that coded for proteins could possibly be interrupted by sequences that did not code for proteins. The conclusion that the two came to was that the process known as transcription into mRNA includes a step that some unwanted loops, also called introns and cut out and the coding sequence, called exons, then spliced back together. One of the consequences to this process is that the same gene can be spliced in many different ways, and then could make many different products. The thought is that during the process of evolution, individual exons could potentially be shuffled around between different genes, and gave a different and quicker source of variation of the random, single-nucleotide mutation.
Fred Sanger and Alan Coulson made a crucial discovery in 1977. They developed what they called the ‘plus and minus’ system to sequence the DNA of the bacteriophage ΦX174, a very small virus. Almost humorous, Coulson and his colleagues made a quicker and simpler method when they were almost complete with the sequencing. The method is called the dideoxy chain termination method. With that new method, they completed the ΦX174 genome very quickly, The final count of base pairs is 5386, a decent number. This dideoxy method that they developed was what led up to the high speed and fully automated sequencing technology that was responsible for the completion of the Human Genome Project in 2003.
The final major discovery of the 70’s was a staggering one. In 1978 Recombinant human insulin was produced. It was David Goeddel and his associates that were responsible for this breakthrough. They used E. coli that had been genetically modified to contain the gene that was responsible for the production of human insulin. This discovery provided insulin to people that crucially needed it.