Genetic Engineering And It's Applications

 What is Genetic Engineering?

Genetic Engineering is the process of manipulating, modifying the DNA or gene of an organism or plant to get a specific trait or character.

Genetic Engineering And It's Applications
Genetically Engineered Goat

This is an example of genetic engineering and we're going to take a look at how this process works. Note that genetic engineering goes by different names, it is called gene splicing, recombinant DNA or genetic modification. But all of these terms mean the same thing which is basically this taking DNA from one organism combining it with another organism and getting recombinant DNA.

 DNA from two different sources now in the case of our goat most of the DNA came from the goat but it received a gene that allowed it to produce needed medicines. Now you might be wondering how is it possible to combine DNA from a goat with DNA of other organism to produce protein HLZ?

 Well the key is that the genetic code is universal so if we were to take a look at the DNA of an animal, the DNA of the bacteria and the DNA of a little boy we would see some differences but they're all made up of A, T, C and G.

 Now the sequence might be different but they're speaking the same language and because the genetic code is universal we can combine DNA from different organisms and genetic engineering is a reality.

 Genetic engineering relies on enzymes. Two types in particular so let's see the role of these enzymes in genetic engineering.

 One of these enzymes acts like scissors it’s known as a restriction enzyme and its job is to cut DNA at particular sequences.

Then there's another enzyme known as ligase. Its job is to glue DNA back together.

what are restriction enzymes???

 Let's explore more about restriction enzymes in a little bit more detail. There are many different restriction enzymes thousands in each enzyme and is specific for a particular DNA sequence. So some restriction enzyme will only cut DNA when it sees the sequence CCTGG or when it sees the sequence TTCG AAA or the sequence CCTAGG.

 The other thing to know about restriction enzymes is that many of them cut unevenly and this is known as the restriction site.

So let's take a closer look at how the restriction enzyme cuts unevenly. Imagine there is a DNA sequence and there is the restriction site for a particular enzyme. It likes to start cutting at one side but then finish cutting elsewhere. So what happens is that we get an uneven DNA sequence. These uneven DNA sequences are known as sticky ends and they are called sticky ends because since there's only one DNA sequence exposed here it can easily bind through complementary base pairing rules to another sticky end and this is important to genetic engineering.

Role of enzymes in creating recombinant DNA

There's our DNA sequence and a restriction site for a particular restriction enzyme. First thing we need to do is add a restriction enzyme to cut it into fragments then we get the sticky ends. Now we're going to add DNA from another source that's also been cut using the same enzyme, this is important because using the same enzyme means that you get the same sticky ends.

 Now these fragments are going to stick together because of complementary base pairing. So here we have one sticky end is complementary to the other sticky end. So they naturally come together however we need a little ligase at this point because ligase will help attach the sugar phosphate backbones which are more difficult bonds to make.

 So once ligase gets involved, we here have our final recombinant DNA. DNA from one organism combined with DNA from another organism. So this is how we would put two different genes together.
 In order for recombinant DNA to actually build a protein that makes a new organism, we need to put this DNA into an organism.

  Genetic engineering in production of insulin

 Let’s take an example a very commonly used example of genetic engineering and this example involves the use of bacteria to be used as human insulin factories.

 That's right because of genetic engineering we can make bacterial cells produce insulin that’s not bacterial insulin that’s human insulin and then we can bottle that insulin and give it to diabetic patients.

Here's how it works first of all let’s start with the bacterium why would we use a bacterium as a human insulin factory. Well one reason has to do with its genetic structure bacteria have a big circular chromosome but then they also have these smaller loops of DNA called plasmids and it's very easy to move plasmids into and out of cells so that's one advantage to using bacteria.

The other advantage is that bacteria are unicellular and they reproduce asexually which means that in a very short amount of time you can get millions and millions of identical bacterial cells clones and this is important if you want factories.

 So let's see how the experiment works. We're going to start with E.coli bacterium you can see it's chromosome, you can see it's plasmid and then we need a human cell and this human cell contains a nucleus which contains DNA and within that DNA is a gene for producing insulin.

 We need to take the plasmid out of the bacteria and we're going to take the DNA out of the human cell. Then we need to cut both of them with the same restriction enzyme. We need to use a restriction enzyme that cuts at sites around the human insulin gene.
Important note:-
 It's important to pick the right restriction enzyme for the experiment.

 Next we need to combine these genes and plasmid together and because of complementary base pairing and because of the sticky ends they're going to naturally bind together.

 Then we're going to add in a little bit of ligase to help seal the sugar phosphate backbones and now we have our recombinant DNA.

Most of the plasmid is bacterial DNA but it now has the human insulin gene. But again this is useless unless we put it inside a cell so that the DNA can be used to make the protein insulin.

We will be going to stick this recombinant plasmid back into the bacterial cell in the process known as transformation. Whenever you give a cell new DNA it’s called transformation. So now we're going to let this bacterial cell reproduce and in a matter of days we'll have millions and millions and millions of identical bacteria all of them with this recombinant plasmid that contains the gene for human insulin.

  After the production of insulin, then what we're going to do is we’re going to take the insulin out of the bacteria there's a special technique where we can isolate that protein.


  Now we've got the human insulin and we can bottle this up and we can use it to treat diabetic patients who need doses of insulin. This is only one example given here, we can move genes from different organisms into other organisms.

 So other applications include:

  1.  Making pesticide resistant plants. These have a gene from bacteria that allows them produce their own pesticide.
  2. We can make bacteria that can clean up toxic waste.
  3.  We can produce proteins to dissolve blood clots.
  4. We can even make growth hormone.

Read Also:

  1. Central Dogma And Production Of Proteins.
  2. How DNA Finger Printing Is Done.
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