Proteins

so proteins are a very heavy topic and biochemistry, and we'll talk a lot of details about proteins later on in our course. Now, in this video, we're gonna do a quick recap on proteins, so recall that proteins are one of four major biological macro molecules that all cells have and proteins have vast structural and functional roles. So we've seen that in our previous bio courses, where proteins do so many different things for a cell, and we'll see that in this course to so proteins are the polymers of amino acid monomers. So all that means is that the monomers of proteins are amino acids and similar to nucleic acids. Proteins have directionality, and all that means is that in a chain of a protein, the ends of that protein are chemically different from one another, and so proteins have an end terminal end and a C terminal end on the opposite end. And so the end in the end terminal refers to the presence of a free amino group and recall that amino groups have a nitrogen atom in them, which is represented by an end. And on the other hand, ah, C terminal is referring to a free car boxful group. And so the C and C terminal refers to the car box a group. So let's take a look at our example and down here. What we'll see is that we have a bunch of amino acid monomers represented by triangles, and these triangles are different colors. So these air different amino acids and through a process we can link all of these amino acids together in a chain to create a protein polymer and notice the protein polymer has directionality. We have an end terminal end on one end with a free amino group and a C terminal end on the opposite end with a free car box over and protein sequences are always referred to from the N terminal to the C terminal end. So in the next video, what we're going to talk about is the amino acid itself. What is this monomer and what are the components? So I'll see you guys in that video

So now that we've refreshed our memories that amino acids are the monomers of proteins, we can now focus on the structure of the amino acid itself and recall that each amino acid contains common components as well as a unique. Our group and living organisms use a total of 20 different amino acids that could be grouped together based off of the properties of there are groups and so in our example below. What we see is that this box shows the amino acid components, and the ones that are bracketed and red are common to all amino acids, whereas the unique components, like the are groups are shown below. So the common amino acid components include a central carbon atom, also known as an alfa carbon, shown here in the amino acid structure. It also includes a central hydrogen atoms shown above and amino group on the end terminal end of the amino acid shown here, and a car box Aled Group shown on the opposite end of the amino acid on the C terminal end shown here. And so the shaded portions that I've just highlighted again are common to all amino acids, So the unique part are shown by the our groups. And over here we have a table of the amino acids and there are groups and noticed that I've intentionally made this table kind of small and difficult to read because we're not so interested in the details just yet. We'll talk about all the details of the amino acids in our later videos. For now, I just want you guys to notice that, uh, each of the amino acid contain a different our group. And you can see that because the are groups are highlighted in blue and the blue boxes are all different sizes. And so, uh, these amino acids you can also see are grouped together based off of their properties. And you can see that by the boxes which are grouping amino acids together. And so in our next video, what we're going to talk about is how amino acids come together to create the different levels of protein structure. So I'll see you guys in that video

in this video, we're actually going to do two different things. The first is we're gonna recap the protein levels of structure. And the second we're going to define several different protein related terms that tend to confuse students. And so, for the first one, recall that proteins can have up to four levels of structure, and they're conveniently called Primary, secondary, tertiary and Quaternary levels of structure. And again, in this video, we're just gonna do a quick recap. But later on, in our course, we're going to dive into a lot more detail for each of these levels of structure. Now, for the second objective, there are several different terms that referred to amino acid chains that vary in length and so you can have short, intermediate and longer chains. And these terms include Ah, lego peptide, peptide, poly peptide and protein. And so, in our example below will first consider the protein levels of structure and then we'll define and distinguish between each of these terms. And so, uh, for the first level of protein structure, recall that it is the primary level of structure, and this refers to the types, the quantity and the order of amino acids from the n terminal end of a protein to the C terminal end of a protein. And the primary level of protein structure is incredibly relevant because it dictates and influences all the other levels of structure. Now recall that the secondary level of structure is the formation of Alfa He'll OSI's and beta pleated sheets, and so recall the Alfa Healy Seas are a winding type of structure, and beta pleated sheets are a zigzag or a staircase type of structure. Now the third level of structure is tertiary protein structure and notice that this includes beta pleated sheets and Alfa Hillis is, but it's really referring to the overall three dimensional shape of that protein. Now Quaternary protein structure refers to a protein that has multiple amino acid chains, and we can see that in this diagram, where we have a light colored gray chain and a darker colored chain. And these air separate chains that have their own three D structure and the complex together to form a single protein with multiple sub units, and every protein has primary, secondary and tertiary levels of structure. However, not all proteins contain quaternary levels of structure. Now, for our second objective of this video. We're gonna define these terms. And so a LIGO peptide refers to an amino acid chain that contains between two and 20 amino acids. Peptide refers to amino acid chains that contain less than 50 amino acids, so you can see that there is some overlap between peptide and a Lego peptide. Now, poly peptide refers to amino acid chains that contained greater than 50 amino acids and proteins contain up to from hundreds up to several 1000 of amino acids. And so notice there's some overlap between protein and poly peptide. Now, really, the main difference between poly peptide and protein is that poly peptide tends to refer to just the chain of amino acids, whereas protein refers to the chain of amino acids, but in its functional form, and so proteins include the functional form. And so in our next video, we're gonna talk about a very specific type of protein, and that's the enzyme. So I'll see you guys in that video

in this video, I'm going to give you guys some quick facts about enzymes. But later on in our course, we'll talk a lot more. Details about enzymes now recall that enzymes or proteins that catalyze chemical reactions or speed up chemical reactions, and they could do so without actually being consumed by the reaction and the reactant of enzymes. Air called substrates and the substrates fit perfectly into an enzymes active site, And then the enzyme converts the substrates into the products. So let's take a look at our example and down here, what we have are two substrates, a red one and a yellow one, and below we have our enzyme, which has an active site in the substrates, fit perfectly into the enzymes active site to create an enzyme substrate complex. And then the enzyme, uh, induces the reaction and converts the substrates into the product, and it does so without being consumed, which means that the enzyme could go back and repeat the reaction on a new set of substrates and enzymes are incredibly relevant toe all life because enzymes pretty much catalyzed every cellular reaction, and they make those reactions occur at a rate that's sustainable for life. And so the last thing I want to leave you with is that the ending A S E is indicative that it is an enzyme. And so, for example, Pep, Today's Ends and A C and pep today's is are indeed enzymes. And again we'll be talking about enzymes throughout our entire biochemistry course. And so that concludes our lesson on enzymes, and I'll see you in the practice videos.

Which of the following is not a component of an amino acid?

• A. Peptide
• B. α-carbon
• C. Amino group
• D. Carboxyl group

Which level of protein structure corresponds to the formation of α-helices and β-pleated sheets?

• A. Primary
• B. Secondary
• C. Tertiary
• D. Quaternary

Fill in the blanks: Enzymes __________ chemical reactions _________ being consumed by the reaction.

• A. Speed-up ; while
• B. Slow-down ; without
• C. Catalyze ; without
• D. Inhibit ; while