Protein, this unknown star
We often hear about it, whether in terms of health or diet, but few people know what it is all about. Where do our proteins come from, how are they made, and most importantly, what are they used for?
To answer that, you have to look closely at a cell and zoom into the nucleus, DNA. It is from this molecule, which contains our entire genetic heritage, that proteins come from. Initially, our DNA, which is in double helix, will open and thus allow molecules called enzymes, to read our DNA and also to produce messenger RNA. This step is the transcription.
It is here that the messenger RNA, which contains the precious information which will allows to produce our protein, will be extracted from the nucleus of our cell to find itself between this one and the membrane of the cell, and thus arrives at the cytoplasm stage. A new mechanism is then set in motion: to obtain our protein, the messenger RNA must be translated. The cell uses a very large protein, the ribosome, another decoder that specializes only in messenger RNA. It will serve as a mounting table for our proteins.
So here we are at the translation stage. For this latter mechanism to work, the intervention of RNA, a molecule from our nucleus, is essential: it is charged with amino acids and energy. This will read and identify three by three the nucleotides (these are complex molecules which form our DNA. In our diagrams they are illustrated by the red and blue bonds between our two strands of DNA) of the messenger RNA. Amino acids, on the other hand, are fascinating molecules that are the basis of life.
Their association and the form they decide to take once assembled can completely change the game, like modifying our protein and its function. Once, this stage of translation passed, we get a polypeptide chain. Clearly the component of our protein. Each protein is thus composed of one or more of these chains. So what are these proteins for, which are only synthesized in 20 seconds and which, depending on their shape, have completely different roles? Well, they do most of the work within our cells – like producing themselves – and, therefore, our organs. For example, antibodies are those proteins that target viruses and bacteria to protect our bodies. They can also take on the role of messenger so that cells can communicate with each other or with the environment around them. We are thus made up of all kinds of proteins, small and large.
These famous proteins are therefore not only found on our plate. Although our body is a wonderful performance machine, we cannot, however, produce all of the amino acids needed to make our proteins. Nine of them must be provided by our food. These are the essential amino acids. This is why a balanced and diversified diet is necessary for the proper functioning of our cells and therefore for the production of our proteins thanks to the amino acids that we have on our plate!
1. Bruce Alberts et al. Molecular Biology of the Cell. 4th edition. Garland Science.2002.
2. Nature.com. Protein function
3. Peter Lengyel and Dieter Söll. Mechanism of protein biosynthesis. Bacterial reviews, June 1969. 264-301. Vol 33. No. 2.
4. Philippe Luchetta. Biologie Moléculaire. Dunod. 2009.
5. Uniprot.org 6. US. National Library of Medecines. What are proteins and what they do?.2019.
7. http://www.hprd.org/. Protein data base.
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