hi and welcome to learn a level biology for free with miss estrick this video is going to go through atp for a level biology if you are new here make sure to click subscribe to keep up to date with all the latest videos so first of all atp is in the biological molecules topic and it is a nucleotide derivative and that is meaning is made up of many of the same structures or molecules that a nucleotide is an atp stands for adenosine triphosphate and its function is as an immediate source of energy in metabolism or biological processes so it's essential that all cells have a constant steady supply so that they can undergo all of the chemical reactions which have to take place in the cell and that release of energy is linked to the three phosphates and we'll have a look at that in a bit more detail so first thing you need to know is the three components that atp is made up of and that is adenine which is a nitrogenous base and what we mean by that is it's a base which contains nitrogen and in this diagram here you can actually see where the nitrogen is it also has a pentose sugar which means a five carbon sugar we can see that one two three four five carbons and the pentose sugar that it contains is ribose the final structure is the three phosphate groups and these are inorganic phosphate groups because they do not contain any carbon atoms so you can see here it just contains phosphorus and oxygen which is what a phosphate group is so sometimes in a word equation or a symbol equation you might see it's shown as just a p or p i to show that it's inorganic phosphate now for aqa the level of detail that you'd need to be able to remember that structure in is just the shape so you don't need to know any of these individual atoms you just need to know you have an adenine base ribose sugar and three inorganic phosphates so atp is made during respiration so you'll have adp which is adenosine diphosphate if i just go back to here you can see that is highlighted here where you would only have two of the three phosphate groups attached so in respiration a condensation reaction occurs whereby one inorganic phosphate group is added to a dp and that is using the enzyme atp synthase and that does take a little bit of energy to do to add and create that bond now the opposite is how atp releases energy so once you have atp created in respiration you can hydrolyze one of those bonds between the phosphate groups to create adp and pi and this also needs an enzyme and it's atp hydrolase and this is the step where you do get a small amount of energy being released when that bond between the phosphate group is broken or hydrolyzed and it's described as an immediate source of energy because in order to release that small amount of energy only one bond had to be hydrolyzed so you get this energy very very rapidly so this diagram here is representing it is a reversible reaction for atp hydrolysis you have to add water and you need atp hydrolyze the reverse of that reaction is how atp is created and this is a condensation reaction because water is removed and atp synthase is required for that reaction as well as a small amount of energy so the final thing is to point out is atp can transfer the energy that is released when that bond is hydrolyzed so instead of it just being released to the surroundings if the inorganic phosphate which has been broken off is bonded onto a different compound that compound will then gain the energy and it becomes more reactive and that is known as phosphorylation and this reaction here adp and pi joining together to make atp that is phosphorylation because the adp is becoming more reactive and it's gaining energy by adding a phosphate group on to become atp and phosphorylation is also the first stage in respiration in glycolysis which is in aerobic and anaerobic respiration so the final thing is looking at some of the key properties of atp which makes it different to glucose as an energy source so it's an immediate energy source as i've said already and that's one of the key differences between acp providing energy for a cell instead of glucose but you could get exam questions asking to compare atp to glucose in providing energy for a cell so the first thing to point out and this emphasizes why atp is more suitable it only releases small manageable amounts of energy when that bond between the phosphate groups is broken whereas if you were to break down glucose you'd get large amounts of energy the reason this is useful is you're going to be wasting less energy because you will only release small amounts if that's not enough you hydrolyze more atp until it adds up to the quantity that you need so it prevents waste and energy and also a lot of wasted energy is in the form of heat so it stops the cells from overheating number two atp is a small and soluble molecule so it can easily be transported around a cell now that is actually the same as glucose glucose can also dissolve in the cytoplasm and transport around the cell and this is useful for both molecules because wherever they are created so glucose might be absorbed but atp is created in the mitochondria perhaps it can still be transferred to other parts of the cell for metabolism number three only one bond has to be hydrolyzed for atp to release energy which is why it's an immediate source whereas glucose you'd have to hydrolyze several bonds so it'd take much longer for it to release all of its energy number four is this idea of phosphorylation that we referred to so with atp when you do hydrolyze the bond between the phosphate groups that inorganic phosphate can be then bonded onto a new molecule and make that molecule more reactive and you can't do this with glucose the final thing is atp cannot pass out of a cell that means that it can't diffuse through the cell surface membrane and there are no protein carriers which it can attach to so every single cell has its own supply of atp or adp and pi whereas glucose can move in and out of cells through channel and carrier proteins so a cell can run out of glucose but a cell will always have a constant supply of either atp or adp and pi so that is it for atp the structure and the importances i hope you found this helpful if you have go and give it a thumbs up [Music]