okay one of my favorite questions to ask my students when we talk about the topics of protein is what is a protein and what i'd like to do as a teacher is i ask them this question i take a step back and let them answer it uh more often than not i'll get answers like oh proteins are basically uh things or food that we need for our body they would give vague answers like oh we need proteins to build muscles we need proteins to be healthy we need proteins to build new cells to grow to repair tissues these were all the things they were taught about proteins when they were studying things during their gcseo levels igcse or you know any levels before a levels right and for the most part they are correct my students will be right and if i ask them so give me examples of proteins then and they will say eggs salmon chicken chicken is quite popular some students will say tofu nuts so all these things actually do contain proteins but it still doesn't answer the question how exactly does proteins work what exactly are they made out of why are they useful in what specific way do we as humans need proteins and not just humans uh we also have to ask ourselves the question uh do other organisms in this world also need proteins the answer is yes every living organism on earth from the smallest bacteria to the largest plant or mammal we can call it blue whale okay we'll need proteins to survive now why do they need proteins to survive is an extremely difficult question to answer because proteins have many functions but before we dive into the importance of proteins and what they are made out of let's do a little bit of revision you might have seen this in your gcseo levels and if you haven't this will give you an idea of how proteins work when you have a leaf over here and the leaf takes in three molecules they have to take in carbon dioxide they have to take nitrate ions and they also have to take in water and when they undergo photosynthesis they will then be able to produce these very small molecules i'm just going to symbolize the small molecules in triangles circles and squares these are just small molecules they don't look exactly like that this is just a symbol um and these small little molecules are basically known as amino acids so once the plants make amino acids the plants will join the amino acids together to make them into proteins and how they join it together we are going to look at it in the next video but for now when you join amino acids together small molecules you make them into a large molecule known as a protein why do plants make proteins plants make proteins for various reasons they may need it for to grow they may need this protein for to function as an enzyme they may they mean this protein to function as a hormone there can be various functions to it now without wasting any time here comes a caterpillar and the caterpillar eats the plant proteins and when the caterpillar eats the plant proteins the plant proteins then enter the caterpillar's digestive system and the proteins are then digested back into amino acids and the amino acids then enter the cells of the caterpillar and the caterpillar uses those very amino acids to make something called caterpillar proteins so what we notice here is the caterpillar is breaking down the plant proteins back into amino acids and repurposing it and building it to become a different type of protein that the caterpillar needs maybe the caterpillar needs proteins to also grow maybe the caterpillar needs proteins to produce a certain type of color or pigmentation of its body so and if this is like for example a silkworm caterpillar silicone caterpillars produce proteins called silk which is used to make clothing and then what happens is a chicken comes along and the whole process starts again the chicken is happy to see the caterpillar over there do not judge the drawing of my chicken i'd fly my bus that's the best i can do i'm not so good with drawing um and the cat and and the same thing happens the chicken eats the caterpillar and the caterpillar protein enters the hen or the chicken's digestive system the digestive system breaks it down back into amino acids and it's then repurposed into the chicken to make it into chicken protein examples of chicken protein will be mussels in the chicken here's where we reach somewhere familiar because if you're a non-vegetarian if you've had chicken before you know that when you eat the flesh of the chicken the flesh of the meat of the chicken contains proteins and when you eat it which is basically the chicken's protein you are then taking the protein it enters your digestive system you break it down into amino acids and your body repurposes those amino acids into different types of proteins for example you for example you may use some of those amino acids to make proteins called enzymes hormones or even antibodies these are some examples of proteins that you may have studied in your o levels igcses or gcses so this just gives us an introduction to what's the relationship between proteins and amino acids so some of my students when they look at this they may think oh my god am i part chicken uh well no because you're not part chicken if you say you're part chicken you're technically part caterpillar and you're also technically a part of the plant but it's not life fundamentally if we just condense this information it just basically means the caterpillar takes materials from the plants to make it into a part of its own body the chicken takes materials from the caterpillar which makes it a part of its own body and we take parts of the chicken so that we can make it a part of our body as well and that's what we do to proteins in fact that's what we do to a lot of nutrients by the way uh but does that mean you're part chicken no you're not part chicken okay that's not what it means at all so don't worry it it doesn't this is not the phrasing so that this some of my students will go aha is that what they mean by you are what you eat no well maybe maybe that's the origin of the statement but i don't think that's what they actually meant in any case this is just basically the flow or the relationship between chickens uh not chicken sorry uh the relationship between proteins and amino acids let's just basically look at the context of proteins uh for the use in humans okay we understand that every living organism needs proteins but to make things a bit simpler for now we want to talk first about why humans need proteins like i said earlier when you studied it before a levels your pre-a level yes you may have been told that proteins are needed to build muscles and two repair tissues but what is a protein anything can be a protein in your body by the way for example your hair your hair is actually made up of proteins called keratin your skin actually contains a protein called collagen which gives it this elasticity its flexibility if you remember when you studied saliva saliva in our mouth contains something known as amylase enzymes and those amylase enzymes needed to digest starch are also made out of proteins other examples of proteins that you might think of as a red blood cells red blood cells themselves are not proteins but blood cells contain very important proteins called hemoglobin which helps to carry oxygen our muscles contain something called contractile protein actin and myosin we are only going to be looking at actin and myosin in chapter 16 in a2 so that's a long way off um so as we can see over here we have different types of proteins that carry out different functions some proteins are needed to form hair some strengthens our skin some carries oxygen some moves the muscle some digest food and you might be thinking oh wow that so proteins can do a lot of things yeah proteins can basically do a lot of things because there are many different there is a diverse uh cornucopia if i may of proteins when it comes to their structure and their functions and how is it possible how can we have so many different types of protein well before we go into that in detail again do you have to know all the proteins in existence no you do not have to know all the proteins in existence however it is very important to know some important proteins in the human body uh we'll have to know hemoglobin we will uh and hemoglobin is going to be talked about in chapter eight enzymes in chapter four is it chapter four i think enzymes is in chapter four i'll just get those two confused i think enzymes no enzymes are in chapter three yeah chapter three we have to know a little bit about collagen we will be talking about collagen later in later videos for chapter two we have to talk a little bit about hormones uh insulin and glucagon this will be in chapter 14 antibodies in chapter 11. so you don't have to know all the proteins right from the get-go we will be introducing different types of proteins in different chapters all right so looking at all this list right here you may be thinking oh wow there's so many different types of proteins that we have to cover so it may be overwhelming but let's start from the basics now if you remember the beginning part of the video i did say that to build proteins you need something known as amino acids so amino acids are basically the building blocks or subunits or monomers required to build or to make proteins i like to use an analogy where i say that amino acids come in a myriad of lego blocks so if i would just basically show you this picture over here as you can see there are many different types of lego blocks okay of varying [Music] shapes and sizes okay and the beautiful thing is when you take these lego blocks and when you join these lego blocks in many different ways you get many different models same thing goes with amino acids as well when you join the amino acids in many different ways you get a myriad or a diversity of proteins that's how you're able to get collagen keratin hemoglobin amylase even though they all came from the basic building blocks of amino acids so without wasting any time let's basically go into the structure of amino acids what you have to know about amino acids are in nature there are 20 different types of amino acids now of course as a student you may think oh god do i have to memorize all these 20 different types of amino acids no you do not need to memorize those 20 different types of amino acids and immediately i think there is a sigh of reliever like oh thank god okay now so and no matter what type of amino acid it is they all have the same basic structure all 20 types all amino acids will have i'm just going to draw a c over here carbon and i'm going to put it in blue as you can see on the right hand side a carboxylic acid group and the carboxylic acid group is c double bond o o h the next group that they also will have is the amine group on the left hand side uh i'm throwing it on the left uh which i'm drawing it in purple i guess that's purple yeah and the mn group is made up of nh2 and they also have something called the r group also referred to as the side chain and these are the three basic groups that all amino acids must have now some students will ask me does the amine group have to be on the left and does the carboxylic acid group have to be on the right not necessarily they have to be parallel to each other though so like for example uh the c the carboxylic acid group can be on the left the amine group can be on the right uh that that's fine too as long as they're parallel to each other you're you're drawing uh the correct amino acid and what is also important to know is the r group has to be perpendicular or at 90 degrees to the carboxylic acid group and the amine group that's important to note now what makes amino acids different from each other so i told you just now that there are 20 different types of amino acids and what makes the amino acids different from each other is the other group the r group is variable for different types of amino acids so what does that mean let's look at it in detail i'm going to draw three amino acids for you ln in bracket ala glycine gly and also serene ser we are going to draw the c h bonds first that's the basic structure you must always know now let's throw it together okay the next group i always like to put is the carboxylic acid group c o o h notice that for alanine glycine and cell in so far everything's exactly the same the carboxylic acid group is the same next we do the amine group and h2 it's the same for all three amino acids again what makes them different however is their r group for lenin the r group is made up of ch3 for glycine however that's just a hydrogen in the up group for 7 however there is a ch2oh2 and i'm going to highlight the r groups to show how they are different from each other so alanine glycine and 7 have the same carboxylic acid group the same amine group however they have different r groups that's what makes one amino acid different from another amino acid again do you have to memorize each of the different other groups the answer is no you don't have to the only thing you have to know however is glycine is referred to as the smallest amino acid amongst all the 20 different types it only has a hydrogen in its article that's all we have to know so we have seen three different types of amino acids and what makes one amino acid different from another amino acid is the other group that's basically it