Greetings! Hope you are doing well in these trying times. I thought a lot about what would make a great first post for a blog. Initially, I gravitated towards writing something related to Linux or maybe another Python post, but it has been done a million times. We will get there, just not today. Today, I would like to bring to your notice one of the more fundamental things about biology, “The Central Dogma of Biology”.
What is the central dogma?
Dogma is defined as a principle or set of principles that are incontrovertibly true. The central dogma is the one fundamental truth of biology. It was stated by Francis Crick. A simple summarization would be that once information flows from nucleic acids (i.e. DNA or RNA) to proteins, it cannot flow back. The process is irreversible. Or in the words of the author,
The Central Dogma. This states that once “information” has passed into protein it cannot get out again. In more detail, the transfer of information from nucleic acid to nucleic acid, or from nucleic acid to protein may be possible, but transfer from protein to protein, or from protein to nucleic acid is impossible. Information means here the precise determination of sequence, either of bases in the nucleic acid or of amino acid residues in the protein.
For me, when I went through the above sentence, I could not make out a lot of stuff. Let’s break down new terms.
- Nucleic Acids: Our very own DNA and RNA. They carry information about the cell and by directing the process of protein synthesis determine what characteristics are inherited by living things.
- Proteins: Macromolecules, consist of one or more long chains of amino acid residues. Proteins are an extremely important part of a cell, they help with various cellular functions like catalyzing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another.
- Bases in Nucleic Acid: Nitrogenous bases. The primary nucleic acid bases are adenine(A), cytosine(C), guanine(G), thymine(T), and uracil(U). Of these, A, G, C, and T are found in DNA while A, G, C, and U are found in RNA.
- Amino Acid: Building blocks of proteins. Gives rise to polypeptides and oligopeptides.
Most common pattern of information flow
So, the central dogma of biology states that information flows from DNA to RNA to make a functional product called protein. The DNA contains information needed to make all our proteins. The pattern for information flow that is most common is as follows:
- DNA Replication: Create new DNA from existing DNA.
- Transcription: Make a new RNA from DNA.
- Translation: From RNA make new proteins.
The image taken from Wikipedia below showcases how this flow of information takes place.
There are a ton of new terms here but they are out of the scope of this article. Maybe I will cover them in some future articles.
Is this all about the Central Dogma?
Fortunately no! There is a lot more information flow patterns present. We just showcased the most common one.
The 3 main characters of our story, DNA, RNA, and protein can transfer information between them in 9 different ways, divided into 3 classes. Of these 3, the unknown transfer is thought not to occur naturally.
It’s easy to visualize it in the table below.
Does the Central Dogma always hold true?
Not sure if it is a good thing or a bad thing, but it does not hold true for nc-RNA. Non-coding RNA is an RNA molecule that although is transcribed from the DNA is not translated into a protein.
So this is it! The end of my very first article! I tried my best to explain what the Central Dogma is and why it’s so so important to biology to the best of my abilities. Any and all criticism is welcome.