Question: What are proteins? What different parts are there in proteins? What do proteins do?

Josh Meyers answered on 14 Jun 2015:

This is a great question!

Proteins are biological molecules that carry out many of the functions of the human body. They come in many different shapes and sizes and can carry out many different roles in the body. Some proteins are very important for life and others we have no idea what they do!

All proteins are made up of amino acids. There are 20 amino acids in humans which can be arranged in different sequences to form different proteins. The sequence of amino acids determines how the protein folds, its function and its properties. There are 9 amino acids which are called essential in humans because we cannot produce them ourselves, and these we must get from foods such as eggs and meat.

Some examples of proteins and their roles:
Taste receptors – recognise food molecules and spark a signal to the brain which says ‘I’ve tasted a chicken jalfrezi!’ (or whatever else you’re eating)

Histone proteins help package our DNA into tiny chromosomes so small they can fit all our genetic information into every cell of the body.

Rhodopsin is my favourite protein, it sits at the back of your eye (the retina) and absorbs light through a small molecule called retinal. When the light absorbs it makes the retinal flip within it’s protein binding site and causes a signalling cascade to make you see! Here’s a very old fashioned video of it:

There are also proteins which are important for diseases to survive, so by stopping their function with small molecules, we can cure disease.