 Hey everybody, Dr. O'Hare, let's talk about proteins. So proteins are going to be polymers or long chains of these amino acid monomers. So all proteins are made of a combination of 20 different amino acids. They all have a lot in common. They all have a central carbon. They have that hydrogen. They have the amino group, which holds the nitrogen. That's the key there, right? Protein is our only source of nitrogen. It's the only thing. All carbohydrates and lipids and proteins all have carbon, hydrogen, and oxygen, but protein is unique because of the nitrogen. And then it's going to have the carboxyl group on the other end as well. A carboxyl group is a carbonyl group, that C double bond O plus a hydroxyl group. But the side chain or R chain is what makes each of these amino, these 20 amino acids unique. So here we see all 20 amino acids. You notice the side group or the variable group, whatever you want to call it is what makes them unique. You'll notice that it changes the properties. Some are polar, some are non-polar, some are aromatic, some are positively charged, negatively charged. Don't really care much about that. It's going to be why each of your 20 amino acids behaves slightly differently. I think that's plenty there. But your body can make, there's 20 amino acids that make every protein in your body. Your body can make 11 of them. So those are called the non-essential amino acids because your body can build them. The other nine are going to be the essential amino acids. That means that your body doesn't make them or doesn't make enough of them. So you have to consume them in your diet. And those are going to be histidine, isoleucine, leucine, lysine, methionine, phenylalanine, or some say phenylalanine, threonine, tryptophan, and valine. So those are your essential amino acids. They have to be in your diet. Now if you consume animal products, they have all the essential amino acids. If you don't consume animal products, you need to eat combinations of foods that would get you all of those. They're called complementary food combinations, but we'll cover that in nutritional topics later. So the other 11 amino acids are non-essential. You don't have to eat them. Nothing wrong with eating them. But if you don't eat them, your body can make them. Some amino acids are called conditionally essential. So if you have like a preterm infant or people that have poor digestion, some of these may actually be what are called conditionally essential, but that's not a huge deal. Another group of amino acids you might see highlighted sometimes are called the branched chain amino acids. They improve athletic performance, muscle growth, et cetera. So a lot of athletes make sure they get diets that are really high in what are called the branched chain amino acids or BCAAs. Those are going to be leucine, isoleucine, and valine. Just so you know. All right. So those are your 20 amino acids, the building blocks that make every protein we have. All proteins are going to be polymers or long chains of these amino acids, and they are held together as you can see here by what's called a peptide bond. So a peptide bond is a special kind of covalent bond that is formed between amino acids that form these long chains. So when you're done, you're going to have a peptide chain, and if you have short peptide chains, they're generally called polypeptide chains, and then we build out and make those larger proteins. All right. So those are the amino acids, the proteins they build, and peptide bonds. I hope this helps. Have a wonderful day. Be blessed.