 In this module, we'll talk about the basic unit of proteins, the amino acids. We look at the structure of amino acids and we'll see how the monomer of this protein molecule form bonds among different monomer units which are the amino acids. As we have already mentioned that proteins are the most abundant macromolecules or the large molecules present in the cell. They perform very important functions. A list of those functions is displayed on the slide. Proteins play an important role in sport providing the structural elements, protection of the cells. For example, our antibodies are made up of proteins. Proteins also can catalyze different reactions. Proteins play an important role in transport within the cell or within an organism. Proteins as I've already mentioned they play a role in defense through antibodies and also through other mechanisms. Regulation and movement. Proteins as we know muscle as actin and myosin which allows muscle to contract both these molecules are proteins. Proteins can also regulate cellular function. We'll look at all these examples of protein functions during the duration of this course but for now I just wanted to emphasize that proteins can perform many many different very versatile functions. The only function proteins don't perform is store genetic information. Let's look at the basic structure of an amino acid. I've already mentioned that the amino acid has two groups and a minogroup and a carboxyl group attached to a central carbon. The central carbon has two other bonds. It forms the central carbon forms a bond with a hydrogen atom and another and another bond with another type of or another group of molecules. In this case this group of molecules or group of atoms is referred to as our group. Next we will also look at some of the features or some of these are groups. What are these are groups because they can have an effect on the structure of the protein after it has formed. We also know that the 20 different amino acids that that can make proteins. We look at all these amino acids. However, I would like to mention that I don't want students to remember or memorize the structures of these amino acids. Please just pay attention to the basic concepts and the basic nature of these amino acids. We are going to divide these amino acids into different groups. Let's look at the first group. A minor acids which have charged groups as you have seen their two types of charges positively charged positive charge and negative charge is a group of minor acids to which have a negatively charged molecule attached to it in the form of our group. For example aspartic acid and glutamic acid both these amino acids have a negative charge because of carboxyl group. The other group is positively charged minor acids three minor acids in it in this group and these minor acid minor acid our groups have a positive charge on them. The next group is a minor acids which are attached to molecules which have no charge. These are molecules which don't have any charge on them. However, they can give special functions to proteins. There's another group of molecules that are group molecules that are polar. They don't have a charge per se but they have polar atoms in them. We have discussed polarity in our previous module and there's a group of amino acids which are special cases three three three amino acids in this group. The most important one that I want you to pay attention to is cysteine because the sulfur atom in cysteine can form sulphide bonds within the protein molecule and that results in a specific shape of the protein. Next I briefly want to mention how these molecules are these amino acids they are linked together. We will cover that in the next module.