complex one all the way through complex for these complexes of the electron transport chain basically function to allow the movement of electrons across the inner membrane of the mitochondria and that ultimately allows us to establish a proton electrochemical gradient along the inner membrane of the mitochondria now following the establishment of this proton gradient the final complex known as ATP synthase or sometimes known as complex 5 of the electron transport chain basically uses that proton motive force that proton electrochemical gradient that was established to actually synthesize and release ATP molecules into the matrix of the mitochondria and in this lecture I like to focus on the structure of ATP synthase complex five of the electron transport chain so just like the previous complexes complex 5 is also found in the inner membrane of the mitochondria and it has the following elaborate structure so the structure of ATP synthase is quite complex and we can break down the structure into two general regions we have the F naught region and the F 1 region now the F naught region is this section here and the F 1 region is this section here let's begin by describing the F 1 region now the F 1 region basically consists of those polypeptide chains which are responsible for actually binding the adp molecules and the orthophosphate molecules and forming those ATP and releasing the ATP into the matrix of that mitochondria so the f1 region is the catalytic unit of this complex so this region basically lies in the matrix of the mitochondria and we find five different types of polypeptide chains with into f1 region we have the Alpha shown in dark green we have the beta shown in light green we have the gamma shown in red we have the Salon shown in blue and we have the Delta shown in purple here now let's discuss this Alpha and the beta we actually have three individual alpha units and three individual beta units and these three alpha and three beta units basically creates this hexameric alpha 3 beta 3 ring structure as shown in the following diagram so these alpha and beta units basically alternate to form this ring structure that consists of these six individual polypeptide chains now the function of this hexamer structure as we'll see the future lecture is to actually bind the ADP and the ortho phosphate molecules to synthesize the ATP molecules and then release the ATP molecules into the matrix of the mitochondria now although the alpha units can in fact buying the ATP molecules only the beta units of this hexamer have the capability of actually synthesizing and releasing those ATP molecules so once again the three alpha and the three beta chains combine to form a hexameric alpha 3 beta 3 ring structure that will be responsible for catalyzing the synthesis of ATP molecules and once again although both of these chains alpha and beta have the ability to bind ATP only the data has the ability to actually synthesize and release those ATP molecules into the matrix of the mitochondria and we'll discuss how that mechanism actually takes place in a future lecture now so we discussed the Alpha and the beta units now let's move on to the gamma and the epsilon unit so we have a single gamma and a single epsilon unit that actually organized they combine to form something called the central stalk and this central stalk is this stroke is this elongated structure that runs through the inner cavity of that hexameric ring and it also connects to this structure that is within the F naught region as we'll see in just a moment so the gamma and the epsilon polypeptide so the red and the blue structures organize themselves to form something called the central stalk and this runs through the inner cavity of the hexameric ring so if we take a cross section of this structure here this is basically what we're going to see so we have these six Reina these six change the Alpha and the beta and through the and through the inner cavity we have that stalk that is made up of this red structure as well as this blue structure as we see in this particular diagram now what's the function of this gamma epsilon central stalk well the gamma epsilon central stalk will essentially connect this structure shown in orange to this structure here and as that stock basically rotates it will cause the catalysis of the ADP and the orthophosphate to form the ATP molecules and the subsequent release of those ATP molecules into the matrix of the mitochondria so once again the gamma epsilon central stalk will interact with the hexamer ring as the stalk rotates it stimulates the synthesis and the release of ATP molecules and we'll discuss the details of that in a future lecture and finally we have this Delta chain as shown right over here now the Delta subunit basically helps hold this entire hexameric structure in place so that it doesn't actually rotate it is also actually used to connect this hexameric structure to this structure here that is part of the F knot unit so now let's move on and discuss the F knot units now the f1 region basically contains the catalytic unit while the F knot region as we'll see in just a moment actually contains that structure that allows the movement of the protons the hydrogen ions down their electrochemical gray from the intermembrane side to the matrix side of our ATP synthase so the F not region is mostly hydrophobic and lies within the inner membrane of the mitochondria and basically consists of two types of units we have the SI units the SI subunit as well as the a subunit and together the C and the a subunit interact to form this proton channel that allows the movement of those protons across the membrane of the of the mitochondria the inner membrane of the mitochondria so the F knot region consists of 10 to 14 C subunits so in this particular case I've drawn 10 so we have 1 2 3 4 5 6 7 8 9 10 of these orange structures and these 10 C units basically organize themselves to form this ring structure which acts as a channel to allow the movement of those protons so the 10 to 14 C subunits organize into ring structure that acts as a proton channel it ultimately allows the hydrogen ions to flow from the intermembrane space and into the matrix down their electrochemical gradient now we also have this a subunit that is shown here and the a subunit basically lies on the outer portion of this C ring structure and the a subunit also plays a role in helping move those protons along the membrane a law across the membrane the inner membrane of the mitochondria now on top of that the a subunit actually also holds this the a submit' also actually connects this C structure to this structure that is part of the f1 unit so as as showed of the following diagram we have a single a subunit that is attached onto this arm which consists of two B change and that in turn is attached onto the unto that Delta subunit and together this entire structure connect the F not to the f1 section so a single a subunit that binds to the outside of the C ring structure and the a subunit helps connect the f1 F not to the f1 unit and also plays a role in proton transport now up to this point we basically see that the F knot region and the f1 region are bound to one another at two locations by two structures the first structure that holds the F knot to the f1 is that central stock that consists of the gamma and the epsilon so the gamma epsilon central star connects the F knot region to the f1 region on top of that we also have this arm on the outside composed of the single a the to be structures and the single Delta structure that hold these two units together so the f1 and the F knot are connected at two points firstly they're connected through the gamma epsilon central stalk and then they're also connected through the arm formed by the a subunit the to be subunits and the Delta subunit now some of these polypeptide chains actually rotate and some of them are stationary so we can generalize and break down the ATP synthase into two regions the rotating region and the stationary region now the rotating region basically consists of the seen ring so this entire orange structure as well as as well as that central stalk that consists of this red gamma structure and this blue epsilon structure so the rotating region the structure that actually rotates as those protons actually move through this ATP synthase is composed of the C ring and the gamma epsilon stock and everything else is basically the stage the stationary region so we see that this a units the to be unit this Delta unit as well as the Alpha and the beta units are all stationary they do not actually move in fact this stalk this section here this a B and the Delta units this structure together holds this hexameric structure in place and prevents it from actually moving so in the next several lectures were actually going to discuss how the or we're going to discuss what the mechanism of this ATP synthase actually is and how the movement of the protons along this region actually allows the structure to synthesize those high-energy ATP molecules