Knowing how DNA works took many decades for science. Although all the mysteries about these fascinating mechanisms have not yet been unraveled, there is already a solid explanation about the nature of DNA and how it works.
The story of the discovery and how DNA works began in 1868, when a Swiss medical student named Johann Friedrich Miescher managed to isolate a substance that was in white blood cells from pus. He called it “nuclein ” and noted that it was acidic.
One of Miescher’s disciples called the same substance “nucleic acid“, since this name was more precise. Almost a century later, scientist Rosalind Franklin studies the structure and tries to unravel how DNA works. He manages to take an X-ray photograph of the DNA molecule.
One of his colleagues, Maurice Wilkins, without permission took the photograph to James Watson and Francis Crick, at the University of Cambridge. They were already building a model of the same molecule and published their findings in 1953. For this discovery they won the Nobel Prize in 1962. Then, gradually, they discovered how DNA works intimately.
What is DNA?
DNA is an acronym that stands for Deoxyribonucleic Acid. This is a chemical compound that is at the core of all cells in the human body. It is made up of a set of molecules, which are known as nucleotides.
DNA contains our genetic information. It is like a kind of manual in which are the biological instructions so that we are as we are and function as we do. Genetic information determines the characteristics of each species and of each individual of the species.
99% of DNA is the same in all human beings. The remaining 1% is what makes each of us unique. Another property of DNA is that it has the ability to replicate itself. This happens when cells divide. In this way, each new cell will have an identical copy of the DNA of the cell that gave rise to it.
As we already indicated, DNA is made up of molecules called nucleotides. These form chains that intertwine and form a double helix. Keeping the proportions, it is as if two streamers were linked together.
The structure of DNA.
The double helix is divided into several segments, each of which is what we know as a gene. The gene is the basic unit of genetic information. Human beings have around 20,000 genes, and each one of them determines some of our characteristics, such as eye color or blood type.
Likewise, the genes are grouped together and form a kind of package, in the shape of an elongated ” X “. Those packages are the chromosomes. They contain groups of genes, sometimes hundreds, sometimes thousands. Not all species have the same number of chromosomes.
Humans have 23 pairs of chromosomes, that is, a total of 46. Half of these chromosomes are provided by the mother and the other half by the father. The whole set of genes, which is in the whole set of chromosomes, is what is called the genome.
One fascinating aspect is that each strand of the double helix has the entire genetic code and is exactly the same as the other strand, but in an antiparallel fashion. This means that one has the code written from front to back and the other from back to front.
Chromosomes are like packets of genetic information.
How DNA works?
The two chains that make up the double helix are held together thanks to the action of four chemicals, which are called bases. Each of these bases is identified with a letter and they are the following:
- Adenine (A).
- Cytosine (C).
- Guanine (G).
- Thymine (T).
The union between these bases is what determines the characteristics of each gene. However, these bases have to fulfill a rule: when one chain has an adenine base, the other has a thymine base. And when one has a cytosine base, the other is guanine. If this rule is broken, an abnormality occurs, which is called a mutation.
As we noted before, DNA must be replicated in order to transmit genetic information correctly. This process is fundamental and determines how DNA works. The process is complex, but it can be simplified as follows:
- At the moment of division, the two chains or strands that make up the double helix momentarily separate. The double helix is temporarily undone.
- A replica is made of each of the strands or chains, but this is “antiparallel”, that is, with the same information written in the opposite direction.
- Thus, two equal DNA molecules are obtained. Each molecule contains an original strand or mother strand, and another strand derived from it. Together they form a new double helix structure.