We all have heard about GENES. But what are they actually? The segment of chromosomes containing the code needed to direct the manufacture of a polypeptide or an RNA molecule are called Genes. A gene basically plays a pivotal role in Genetic Coding.
Also, in this article we are going to see what is collection of Genes called and it’s function. Another important topic that we are going to discuss is vaccine generation and it’s process.
What is Genetic coding?
Genetic code basically is the sequence of nucleotides that shows which amino acids should be linked together to form a particular protein. But as said before we are going to discuss this in detail, so the first thing first- We know that a Gene is made up of DNA and the DNA is made up of nucleotides. These nucleotides contain sequences of nitrogen bases which are of four types – A, T, C, G. Now, these 4 bases make up the codes that are understood by the cells to produce the proteins.
How these A, T, C, G breakdown into a code? and how cells read the information to produce proteins?
Well, the proteins are made up of amino acids and there are 20 amino acids. The structure of these proteins depends upon the sequence of the amino acids. Each amino acid has a specific code made of the bases A (Adenine), T(Thymine), C(Cytosine), and G(Guanine). For 20 amino acids, there are 20 different code words. Each code is 3 bases long. The reason behind this is to get proper 20 combinations for 20 amino acids.
So, if these codes were 2 or 3 bases longs they would have given less than 20 combinations of amino acids. Since, these code words contain 3 bases they make 64 such combinations and that is why each amino acid has more than 1 combination. And the code words are called DNA codons. The RNA codons that are produced from the DNA codons are very similar to it. Meaning in RNA codons in place of G there is C. In place of C, is G, and in place of T, there is A.
In RNA codons, U replaces A, as it contains nucleotidewith U instead of T. Now, these RNA codons read the message from the DNA in the nucleus and convert it into RNA message. This message then travels somewhere else, and convertes into amino acids and then into Proteins. As RNA codons work as messenger they are called mRNA. The process of synthesizing mRNA from the DNA codons is called transcription.
Collection of Genes
Genome is the entire collection of genes present in an organism. In simple words, the genome is nothing but all the genetic material in a cell of an organism. The human genome is 3.2 billion letters long. All these letters together can fill up a 61m high stack of paperback books. The genome of humans is made up of nothing but DNA. And we already know that the DNA is made up of nucleotides.
While the nucleotides are made up of the nitrogen bases – A, T, C, G. These bases then link with each other to form the double helix of DNA. The A and T are always linked up together whereas C and G always together. The genome of all the species is very similar to each other. For instance, the genes of human beings are 98% similar to that of chimpanzees. And the genome of all human beings is 99.9% the same. It is only 0.1% of the genes that make us different from each other.
This difference of 0.1% gives us so much uniqueness. Now, not the entire part of a DNA contributes to building a life. Only some of the segments do. These segments are what we call genes. These genes and the DNA present in them are stored on something called chromosomes. Chromosomes are nothing but thread-like structures present in the nucleus of the cells of organisms. Humans have 46 chromosomes. Each parent contributes 23 chromosomes to their offspring.
With the help of the nucleotide sequence of DNA as a guide the mRNA is produced in the nucleus. The mRNA is important as it instructs the synthesis of proteins. Therefore, this mRNA formed in the nucleus is then transported to the cytoplasm. In the cytoplasm, mRNA links to the ribosome. The mRNA then with help of its nucleotide sequence converts the amino acids into proteins.
These are the important bodybuilding proteins of our body like the keratin which forms the tissues of our nails and hair. Amino acids are also called as building blocks of life. The reason behind this is that they produce proteins that further make cells. Many cells together form the tissue. Many tissues together form an organ. Many organs together form a body.
The Human Genome Project
The human genome project was crucial and huge. And Scientists across the world had collaborated on this project. This project was basically about finding the sequence of bases in the Human Genome. The project began in year 1990 and ended in year 2003 which was two years ahead of the schedule. It had cost around 3 billion $s.
How is this information helpful?
This project has helped the medical field find out genetic causes behind the disease like cancer. With the help of this information, it can be found if someone is the carrier or sufferer of any genetic disorder. It has helped in designing certain medications and predicting their pros and cons. It has also helped in the fields of agriculture, biofuels, animal husbandry, anthropology, etc.
A vaccine in simple words is nothing but using the same defense technique that the body uses to prevent itself from any damage from a foriegn microbe. So, to understand vaccines in detail we have to first learn about how our Immune system works.
Body’s Immune System
Whenever a foreign microbe enters our body, our body starts fighting the microbes and tries to kill them. While our immune system fights with the microbe, our body gives us signs in the form of fever, inflammation, or coughing. The adaptive immune system of the body also gets activated during this period. The adaptive immune system is basically a sub-immune system. And it is also called the Acquired immune system. This sub-immune system creates a immunological memory.
As a result of which the body responds in a more enhanced way if the pathogen invades the body again in the future. Especially by producing specific antibodies to fight that pathogen. Lymphocytes are the leading cells of the adaptive immune system. There are two types of lymphocytes the B cells and the T cells. The B cells secrete the antibodies. Antibodies are nothing but proteins. Antibodies are also called immunoglobulins. Whereas the T cells carry the function of cell-mediated response.
If we already have an inbuilt system to fight the foreign
microbes then why do we need vaccines?
Well, we need the vaccine because sometimes the body might take a long time to learn how to fight a particular pathogen. And sometimes the body is not strong enough to fight the foreign microbe. In this case, if the pathogen is dangerous then it can cause severe damage to the body. For instance, the coronavirus.
So, before the body learns how to fight it, the coronavirus can already cause damage to the body.
How does a vaccine work
Vaccines prepare the body to fight a particular pathogen before the real pathogen invades the body by already creating immunological memory. Now, this immunological memory is created with help of different types of vaccines.
Types of Vaccines
1. Live Attenuated vaccines
Very weak version of the pathogen are used to make this vaccine.
2. Inactive vaccine
An already dead pathogen is used to make this vaccine.while making both of these vaccines it is ensured that the pathogen are weaken enough/ killed properly so that they don’t grow into a disease. But both of these vaccines have their own drawbacks. Live Attenuated vaccines have a little risk because if a person has a low immune system he might get the disease and become infected. Whereas in the case of Inactive vaccines the effect is not long-lasting.
3. Subunit vaccine
A fragment of the pathogen is used to make this vaccine. A fragment of the pathogen is enough to trigger the immune system.
4. DNA vaccine
To date, no DNA vaccine is approved and these vaccines are still being made.
The process of making a Vaccine
The process of generating a vaccine involves three stages- Research, Testing, and Manufacturing. This process under normal circumstances takes around a decade or two. But during the times of a pandemic like now scientists try to make them as quickly as possible.
During this stage, scientists explore the different methods of developing a vaccine. They try to choose the safest and replicable method to introduce the pathogen to our immune system. But all of the methods of developing a vaccine require a good amount of time. So, during the times of a pandemic, it is possible to a make vaccine only if many labs explore different methods at the same time.
Even if a vaccine is ready to test it does not mean that is ready to be approved. It still has to go through many trials in the three phases of the testing.
Phase 1 trial
This trial focuses on how the immune system responds to the vaccine and is the vaccine safe enough.
Phase 2 trial
This trial focuses on the right amount of dosage and how it can be delivered to a wider population.
Phase 3 trial
This phase focuses on what are the side effects of the vaccine. The results are reviewed by a national regulatory authority only if all three trials are carried out sucessfully. And then finally, the vaccine is approved for manufacture.
Every vaccine is unique. Therefore, it requires specialized pipelines for it’s manufacture. But this entire process has to be done in a very short period of time during the times of a pandemic like now. And it is possible only if the laboratories and manufacturers across the world work in coordination.