 Protein is sort of a basic structure that's found in all of life. It's a molecule, and so I like to visualize this with a kind of abrasive analogy. This is from my son, and these beads represent kind of individual amino acids. So protein essentially is a string that's made up of these little individual pieces, and there's 20 different amino acids that you can combine in any kind of different way. The last thing is a protein then doesn't usually exist as a string but actually folds up into a particular shape, depending on the order and how those different amino acids interact together. The amino acids in our body come from the food that we eat, and we also make them. So other animals make proteins, so we eat those, take those in, and we actually take that chain and break it down into the individual amino acids, and then we can rebuild it in any kind of combination that we want. So it turns out we can about half of our amino acids on our own, but the other half we have to get from our food. So meat and things like that have a lot of protein content in that, and a lot of that has to do with muscle. There's a lot of protein that's required to make your muscles move, and then once they're broken down they kind of float around inside the cell, those little individual beads in our analogy, and then inside the cell your body basically connects them together to make the proteins that your body needs to make. And then in our own body, it's still kind of debated how many different kinds of proteins, but there's lots of different ways in which we can find these little bead-like amino acids into longer chains. So yeah, proteins carry out a lot of different roles in the cell. There's kind of a few different main categories they fall into. One is structural, so your body is made up of particular structures and they can be kind of string-like structures or globules. They're things that anchor from one cell to another, so proteins take on that role. Another big role that they take on is kind of biochemistry, how your body carries out particular reactions in your cell from breaking down fat or amino acids or other proteins that we talked about to carry on oxygen. Hemoglobin is an example of a protein, so they're carrying out these special chemical reactions inside your cell. And there's a number of other reactions that have them, but those are kind of the two main categories of functions that your proteins carry out in the cell.