03. Proteins

We think of protein as being a food group – meat and pulses – but this stuff called ‘protein’ is made up of lots of very different individual ‘molecules’. A molecule is what you get when lots of atoms – of carbon, hydrogen, oxygen, nitrogen and other elements - are stuck together. You can make models of different molecules using blobs of playdoh and straws or computer animation programs. Protein molecules are far too small to see with a microscope that would show us cells easily. They’re what cells are made out of; they make up the stuff that cells are glued together with and they are how cells communicate with each other. ‘Enzymes’ are a type of proteins that help chemical reactions to happen and are important in our bodies for things like digesting food. The specific 3D shape of each protein molecule is very important for how they stick to each other and carry out their specific jobs inside our bodies. Our skin is made from lots of different cells and proteins all sticking to each other. 

Protein molecules are long chains of amino acids (smaller molecules). When we eat protein, our digestive system breaks that delicious steak up into individual amino acids and takes them into our blood. Our bodies can then put the amino acids back together again in a different order to make the proteins we need – turning cow protein into human protein! 

There are 20 common amino acids, each slightly different, a bit like having 20 different types of Lego blocks.

When they are stuck together following specific instructions, we end up with a protein that can contain hundreds or thousands of amino acids (a big molecule). This might look like an impressive Lego sculpture… or a small part of one. Creating a protein is like following the Lego instructions. If one step is missing, or you accidentally turn over two pages at a time, the whole, beautiful protein at the end can be completely broken. Quite often, the final, working protein, is made up of many different smaller proteins, each one a separate chain of amino acids from a separate instruction booklet, all carefully linked together. When we talk about proteins like keratin and collagen, we are talking about huge protein structures that are put together from lots of different, smaller proteins, each one with its own instruction booklet (gene) and specific order of amino acids. These chains of amino acids twist around each other and stick together in specific ways to make lots of different versions with slightly different jobs within our bodies. Keratin and collagen are actually groups of proteins. There are lots of different types of keratin and lots of different types of collagen but they are both proteins that form long fibres by twisting chains of amino acids around each other. 

 

Image credits: 

Amino Acid Structure, by Techguy78. Licensed under the Creative Commons Attribution-Share Alike 4.0 International license.
Lego blocks, by Ypiyush22. Licensed under the Creative Commons Attribution-Share Alike 4.0 International license.
Collagentriplehelix-es, by Vossman, Modificado por Alejandro Porto. Licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.