Glycogenesis & Glycogenolysis

I've run dr. Mikey in this video we're going to take a look at glycogen ASIS now the word glycogen SS has the prefix glycol which means glycogen and the suffix Genesis which means the beginning of so it's the beginning of glycogen what is glycogen it's the stored form of glucose and what is glucose well it's that monosaccharide that simple sugar that we use to create ATP and we know from previous videos that one molecule of glucose can produce around about 34 to 36 ATP molecules so it's a really efficient way of creating energy now we know that we can take glucose and we can absorb it into the body and it can go into a number of different cell types to use to make energy but in what situations do we want to take glucose and store it in the form of glycogen well these are going to be fed States so just after eating also known as the absorptive state zero to four hours we're going to be taking the glucose we've just ingested and we're going to store it as this glycogen all right so we've got glucose you can see that there's six carbon 12 hydrogen six oxygen and I'm going to simplify this ring-shaped structure of glucose into this structure and you can also see that I've labeled the six carbons that's where the first carbon is second third fourth carbon fifth carbon and six carbon this is going to be important because when we create glycogen all we do is snap together glucose we have to change it a little bit but basically we're snapping them together to create this molecule that we can compactly store within the liver or the muscle or the kidney so here's glucose first step is we need to turn this glucose into something called glucose 6-phosphate and you're probably aware that glucose 6-phosphate is the first step in the glycolytic pathway it's also the first step in creating glycogen how do we do it we take some ATP give that glucose one of those phosphates we now have adp diphosphate adenosine triphosphate to adenosine diphosphate and we snap that ATP here now which carbon is that one two three four five six it's on a six carbon so it's called glucose 6-phosphate perfect now what we need to do is take that phosphate and put it in another position we do this with another enzyme called phosphoglucomutase take it off sixth position put up on the first position so there's the first position now we've got the phosphate there now the next step is different what we get is something called uridine tri phosphate now this uridine is telling you that there's a nucleotide what's a nucleotide remember nucleotides are really important components of DNA and we've got nucleotides they can turn into amino acids and proteins we've got the nucleotide uracil here and we've got yer adine tri phosphate so there's three phosphates as well we take the Euro diene and one phosphate pop them off connect it to that phosphate so now we've got two phosphates and the uridine so its uridine diphosphate attached to the first carbon there's the uridine diphosphate and what we're simply left if we take that off is two phosphates okay so the uridine triphosphate just turns into diphosphates okay and now we've got this uridine diphosphate attached to the first carbon of the glucose we can now snap these together to create glycogen and what we do is we take an enzyme called glycogen synthase and make sense snap things together we take a glycogen a glucose molecule and we pull off the UDP and it facilitates the linking together at which carbons at the fourth carbon and the first carbon fourth carbon first carbon fourth carbon first carbon and we put this process on repeat you can see that at some points you have different branching and you can see that the six carbon can also bind to the first carbon and then here we've got fourth and first so what type of binding do we have we've got one to four binding and we've got one to six binding and what we end up getting over time over this period is this very branched molecule that we call glycogen now here's an important point when we store glucose in the form of glycogen this is how animals store glucose so animals store glucose in the form of glycogen plants store glucose in the form of starch and cellulose and they are really really similar to this structure in actual fact what you find is that starch is nearly identical it's just not as branched so it's the same bonds what you're going to find it was cellulose is it's the same one two four bonds however what you're going to find is that nearly every second glucose is flipped upside down so what that means is this is down here and this bond like this is up like that for every second one and this is important because the enzyme that we use when we are now in a fasting state a post absorptive state and we need to break this glycogen down back into glucose to use for energy we need to chop leaves one two four bonds and one two six box and we use an enzyme called amylase to do this right so when we have glycogen or starch we can easily chop it up with this amylase but if we're ingesting cellulose certain plant material we don't actually have the enzymes to break these every second bonds where it's flipped upside down and this is the reason why we can't break down grass for example in the form of cellulose but cows can they do have the enzyme that can chop this up so what we now have is an indigestible carbohydrates because glycogen is a carbohydrate just a complex sugar molecule and that ends up becoming fiber so this is the quick process of glycogen

Channel: Dr Matt & Dr Mike

Views: 20,772

Rating: 4.9629631 out of 5

Keywords: glycogenesis, glycogen, glucose, sugar, storage, liver, metabolism, energy, anabolism, catabolism, glycogenolysis, carbs carbohydrate, biochemistry, nutrition, dietetics, nursing, medicine, nclex

Id: ENTdd_dsJTE

Length: 5min 50sec (350 seconds)

Published: Thu Jul 16 2020