 As a kid, the candy store was my paradise. As an adult, the candy store is still my paradise. Except now, when I eat way too many 5 stars, a tiny voice in my head will remind me to take care of my blood sugar. Man, I hate that voice. But it has a point. Sometimes your body is unable to break down all the sugar or glucose it consumes into energy. Why? Because the hormone that is supposed to break down all the sugar isn't enough or the body resits its function. This hormone is called insulin. And if there isn't enough insulin in your body or if there's some kind of malfunctioning with it, then your blood sugar levels will spike like crazy. This condition, this entire condition where insulin is not enough, is not present in enough amounts in your body or if it's not functioning properly or your body is resisting it, a condition like this is characterized by really high levels of blood sugar. And this condition is called diabetes. Diabetes. Now diabetes does not have a permanent cure, at least not yet. But it does have some really effective management methods. One such method is to inject insulin. If your body isn't producing enough insulin, you might as well just supply some instead, right? That's pretty easy. Or is it? Let's talk about the type of insulin a diabetic person usually takes. In the olden days, aka sometime between the 1920s and the 80s, insulin was sourced from animals like pigs and cattle. But this wasn't very fun because it came with a bunch of different problems. Animal sourced insulin isn't exactly the same as the insulin that is produced inside of us. Being a foreign object that is being introduced into our body, our bodies weren't very welcoming about it. That's why allergic reactions were very, very common with this type of insulin. In fact, there would be pain and irritation and swelling even at the site of injection. Other than that, animal insulin took a much longer time to act. After injecting it, a person would have to wait for like three to four hours before it started working. That disrupted meal timings and lifestyle. So you can say that it was slow acting in a way. If all of this wasn't enough, animal sourced insulin was super expensive. Now all of these problems required a solution. So sometime in the 1980s, scientists thought that, you know, what if we could use bacteria instead? What if we use bacteria in order to produce this insulin? Right? Like that would be great. And it is this thought exactly which kind of paved the path towards genetically engineered insulin or human insulin or humulin. So let's write that down. Genetically engineered insulin is also called human insulin or humulin. So this right here, the insulin that we get from bacteria. Now why was this even a topic like, why did we even come up with the idea of bacteria producing insulin? That's because this human insulin or this genetically engineered insulin that we produced from the bacteria, it was not only very cheap to make, but it also didn't have any of these problems that we were facing earlier. So I forgot to add expensive here. So let's add that too. So neither of these issues were there in this new form of insulin that we could produce from the bacteria. So how did we do that? How did we end up producing insulin from bacteria? In order to make insulin from bacteria, the very first thing we did was that we extracted the insulin gene from the pancreatic cells with the help of restriction enzymes. You know those enzymes which kind of act as molecular scissors and you can kind of cut or snip the gene. So those ones, we used those restriction enzymes and we were able to quickly chop off or cut or snip off this insulin gene from the pancreatic cells. Now why the pancreatic cells? Because pancreatic cells are the ones that produce this hormone, this insulin, specifically the beta cells of the pancreas. Now this is the beta cell right here and this is our insulin gene that we are going to extract. Now once this insulin gene is extracted, we kind of glue it to the plasmid of an E. coli bacterium. So this round thing that you see over here, this is the plasmid and if you look closely, let's just zoom in a little bit on this. So if you look a little closely, you can see that there is a small portion of this plasmid which is blue in color which indicates that we have extracted our insulin gene and ligated or glued it to the plasmid of the E. coli bacterium. Now again, why are we choosing E. coli bacteria to be so specific? Why not just any other random bacteria? Well, we have a huge list of advantages that kind of comes with E. coli. For example, like the medium you need to grow this bacteria is very easily available, the requirements are easy and they have a really high growth rate. So they grow very fast and they grow in a lot of numbers. They're really easy to handle with and they are super, super cost efficient. So because of all of those reasons, we thought that scientists thought that E. coli would be the perfect candidate to go ahead with this experiment. Now once we have extracted the insulin gene and glued it to the plasmid of the E. coli bacteria. The E. coli bacteria will now be able to produce the insulin because they now have the gene to produce it. So when it is fused like this, let's choose a different color here. So these red color dots are now insulin. So this is insulin. So once they have the gene for it, they can go ahead and produce the gene product which is insulin in our case over here. Now once this E. coli can produce this insulin, what we are going to do is we are going to add this E. coli culture or this E. coli bacteria into fermenters and increase their growth. And then we are going to extract all of the insulin that is being produced by all that many bacteria. Awesome. So we have our insulin right over here. We have extracted it from our bacteria. It's ready and good to go. Or is it? Well, there's still a slight problem over here that we need to address. You see this insulin that is being produced, this insulin is, it's not the matured version of the hormone. So this insulin right over here that is being extracted from all of this bacteria, it's a pro hormone. Now what is a pro hormone? Now pro hormone is one of those hormones that needs to be matured into the functioning hormone. So this insulin is actually pro insulin. This right over here, this is pro insulin. And this pro insulin needs to mature into insulin, like something like this. Now this maturation kind of takes time and it is just how it is in all of us and every other mammal out there. So in order to reduce this time that it was taking for this maturation to happen, the scientists thought that, you know, they could build something much better than what they actually came up with. Now if you look at the structure of the pro insulin molecule that I have right over here, you will see that it is made up of two short polypeptide chains. There's A and B and both of these chains are linked to each other by these disulfide bonds between them. But that's not all. Right between A and B, you will find that there's another short sequence of peptides right over here and this is called the C-chain or the C-peptide. And whenever this pro insulin is matures into the insulin, what happens is that the C-peptide chain, this gray color chain right over here, it is completely removed. So in that case what will happen? This is a matured insulin molecule right? So in this case we will not have the C-chain or the C-peptide chain thingy at all. So it will just be A and B like this. So this is A, this is B and they are connected to each other with these disulfide bonds. This is what the mature insulin should look like. So to make things a little more advanced than what the scientists actually came up with, they decided to produce these two chains of the insulin molecules separately. That means that they used a bunch of E.coli to produce the A-chain separately and then a bunch of other E.coli like a separate bunch of E.coli to produce the B-chain separately. So each of these chains of insulin were produced differently. One insulin with just the A-chain in a completely different E.coli bacteria and then there's another insulin with just the B-chain again in a different set of E.coli. After these two insulins were produced and they were extracted from the bacteria, what the scientists did is that they combined these two chains together by creating the disulfide bonds between them. So you can see that there are these disulfide bonds between chains A and B in the insulin molecule. So they decided to combine the A and B chains by creating these disulfide bonds artificially. And boom, we have the mature insulin molecule right then and there. And now if you inject this insulin molecule directly into your bloodstream, it's going to start acting just then and there immediately. So that's pretty cool, right? Like we came up, we decided to use a bunch of bacteria and produce insulin from that. That's quite crazy and quite mind-blowing in my opinion if you ask me. In fact, the insulin which you will get in the market these days, in the markets these days for diabetic people, it's this engineered, genetically engineered human insulin only. This is the exact same product that you will get. And this has been a life saviour for diabetic patients all around the world. It is extremely potent and has shown brilliant results for diabetic patients around the world.