History of DNA

Keywords

DNA, history, Charles Darwin, Gregor Mendel, origin of species, variation, dominant, recessive, genes, Friedrich Miescher, deoxyribonucleic acid, Eugenics, Sir Archibald Edward Garrod, Alkaptonuria, Oswald Avery, transforming principle, Erwin Chargaff, guanine, cytosine, adenine, thymine, bases, Rosalind Franklin, x-ray, crystalline scanning, James Watson, Frances Crick, Maurice Wilkins, chromosomes, human genome, cytogenetics, Frederick Sanger.

Introduction

Our DNA has been around for centuries, but the study of it, and the visual presentation of it has not been as long. Here, we take a slight in-depth look at the history of DNA.

First Impressions - 1800s

Let's start way back in 1859. This is when Charles Darwin first publishes his book, 'The Origin of Species'. When he visited places around the world on his expedition with HMS Beagle, he wrote a lot of information about the species he looked at. Although this wasn't relative to our actual DNA, it did set the precedent as to what we know about our own DNA, and that of other organism.

During 1866, Gregor Mendel, an Augustinian monk, looked at Charles Darwin's collection, and further worked on them. He is widely considered the father of genetics, due to his papers and experiements. He figured out what we now use in a Punnett square, using pea plants to show recessive and dominant genes, among other aspects. He released a paper in 1866 which described invisible factors that provide us with visible traits. This was later to be known as genes.

Last one in the 1800s, as in 1869, Friedrich Miescher identifies 'nuclein', which we now term as DNA (Deoxyribonucleic Acid). He also came across a substance that was unlike what he had seen before. He sensed the importance of this and wrote down his findings.

Unfortunately for him, this information would take another 50 years before it was recognised.

Now We're Cooking - 1900s

There was a lot of development during this century. It all starts with the Eugenics movement. This was a period of darkness, where people did not understand what they had found. In 1900, Mendel's work was rediscovered, and was quickly converted to a mathematical science, with predictions made about traits such as height, eye colour, etc.

What then happened was the darker side of genetics, with the Eugenics movement. This was where scientists were looking at how we can grasp these traits and be able to control others. The first quarter of the century saw us looking at changing to make the human race a more superior race.

A couple of years after the turn of the century, Sir Archibald Edward Garrod associates the first disease to Mendel's theory. His theory behind Alkaptonuria, a urinary genetic disease that doesn't break down two protein building blocks, he figured out that it was a recessive disorder. He published an account of what happened when he investigated it. This was the first time he noted something being linked to a metabolism, and noted that it was his belief that some diseases were because there were errors in our chemical pathways.

Fast forward to 1944, and Oswald Avery. He identified DNA as the transforming principle. Up until this point in time, genes were known to be the discrete units of heredity, as well as generating the enzymes which controlled metabolic functions. This is when DNA was linked to being the transforming principle.

Post-World War Two

A big moment in 1950, where DNA was figured out to be species specific. Erwin Chargaff began working on the chemistry of nucleic acids. He was able to specify in research that there were equal amounts of Guanine and Cytosine units in a double-strand of DNA, and that there are equal parts of Adenine and Thymine units there too. His other finding was that the composition of DNA is different between species.

A couple of years later, in 1952, Rosalind Franklin was the first person to successfully photograph (through x-ray) strands of DNA in its double helix formation as we know today. Unfortunately, she was beaten to the post by two other scientists - James Watson and Frances Crick.

The big find in 1953 - the structure of DNA - was found by James Watson and Frances Crick. As a result of their work, they were awarded the Nobel prize in 1962. The other scientist given recognition was Maurice Wilkins. Unfortunately, for Rosalind Franklin, she did not receive recognition, even though her photographs helped the other three to find the structure. She later died in 1958 after a battle with cancer.

Forward some more to 1959, and a copy of Chromosome 21 is linked to Down's syndrome. It was through a form of research called cytogenetics, which is the research on chromosomes. During the late 1960s and 70s stains were introduced which enabled scientists to see individual chromosomes.

The swinging 60s saw some development, but items with significance include the ability to show that RNA could be broken down with an amino acid, thus opening up the code of DNA. By 1965, Marshall Nirenberg sequenced this code, which allowed future scientists to know how the four bases connected.

The 70s saw scientists research the RNA code further, but also Frederick Sanger devlopes a quicker way to sequence DNA. He figured out that if proteins were ordered molecules, then the DNA that makes them are also ordered. His work on sequencing RNA, and later applying it to DNA became the primary method and it still used today.

In 1990, the Human Genome Project was started. It was a project that was set out to last 15 years, with a 5-year mission to map the human genome. This was to help with medications, and to identify mutations that nuclear radiation might cause.

Also in the 90s, the first bacterium is sequenced, Haemophilus influenza. This is an infection that can infect children and affect the ear, as well as causing meningitis. It was the first time the shotgun sequence was used, and proved to be a success, as an even quicker way to sequence DNA. In 1996, Dolly the sheep was cloned. She was able to live a full and healthy life, and reared her own offspring. She is currently in a museum, stuffed. In 1999, the first human chromosome is decoded. The chromosome in question was Number 22, which contained 33.5 million chemical components.

The Next Century

We've now reached this century. We've only been in it for 21 years, but we've already done so much. Smaller organisms have had their DNA decoded, such as the fruit fly and the mouse, and in 2003, the human genome project finished. Through this research, scientists found out that our DNA had a relatively small amount of protein-encoding genes, and that there were similar genes with the same functions present in different species.