As a 5th grader, I bet you already know a bit about molecules and their basic properties. Proteins are "macromolecules" (a very large molecule commonly created by polymerization of smaller subunits or monomers). They are typically composed of thousands or more atoms.

A protein is made of up individual amino acids linked by a special covalent bond called a peptide bond. The cells in our body can make some of these amino acids but there are others that we need to get in our diet. Each specific type of protein is made of a unique string of amino acids. These strings of amino acids can fold up into special shapes and also interact with each other in ways that create complex structures in cells. Each type of protein comes from the transcription and translation of a specific DNA sequence (gene).

But what do proteins do? It turns out that just about everything that happens in your cells and thus in your tissues, organs and body is due to the different proteins. Some of them are enzymes - they convey sugar to energy packets (ATP) that your cells can use, they move nutrients across cell membranes, they insulate the nerves in your brain and much more!

Life is mostly made of a bunch of similar things repeated over and over again like beads on a string. Many times, there are only a few different types of beads, but the many different ways that they can be arranged allows living things to survive. The best examples of this are DNA, fats, sugars, and proteins.

Proteins are strings of around 300 “beads” called amino acids (though they can be much longer or shorter). There are 20 different amino acids which leads to a pretty much infinite number of proteins that can be made. Proteins form the basic machinery of the cell. They make structures to support the cells and have many functions such as using food to make new things for the cell. A large proportion of a cell is made of proteins because they’re just super useful, they do about anything! You’ve probably heard about DNA contains the information about us. The main reason why DNA is important is because it has instructions for making proteins. DNA is basically a manual of all the proteins a cell needs to makes and when it needs to make them. So proteins are really what make complex life possible because they have endless functions that allow life to adapt to just about anything.

A protein is a long string of amino-acids connected to each-other end-on-end. These amino-acids have chemical reactors on each of them, and these in the right order can cause other chemical reactions, which are how a protein functions.

Your body and all other living things are made up of little chemicals which are essentially building blocks. These chemicals are sorted based on what they are made of. Proteins are a one of those types of chemicals. Others are fats, or sugars, or acids. When these are put together, they make living things. If you look at the nutrition information on your favorite food, you will see these chemicals listed. When you eat foods, your body takes in these chemicals to build itself. Proteins are particularly interesting chemicals and make up most of the moving parts in your body. Here are some examples:

- This protein is called a "motor protein" and walks along your cells carrying things: motor protein

Other motor proteins cause your muscles to flex. These are very, very small and not even directly visible with a microscope.

- Transport proteins use energy to pump things into or out of your cells: transport proteins

- Hemoglobin is a protein that makes your blood red. It binds oxygen (blue in this animation) and carries it to your cells that need it: hemoglobin

Proteins can do many many things, and we are still discovering all their functions!