Hope you and your loved ones are at home and safe in such times of crisis. After seeing a lot of misinformation due to the coronavirus my blog would try to spread facts about the biology of the virus to the people with a non-biology background on how the virus infects you and spreads in your body.
So what is a virus?
Viruses are organisms that are classified as non-living organisms when they are outside the cell. Viruses can be compared to parasites as they derive nutrition and energy from the host cell. Most importantly, viruses can only multiply when they are in the living host cell.
Viruses are of two types
DNA based viruses:
- All of your relatives must have said sometime that your eyes are like your mom and your nose like your dad. Thanks to the DNA. DNA is a unit of heredity and plays many crucial roles and acts as your body blueprint.
- DNA is a molecule having two strands running parallelly that carries our genetic information and passes it to the next generation. For example The colour of our eye, or structure and function of all the cells present.
- The mutation in the DNA alters the structure and functionality of cells that cause genetic diseases, such as Down’s syndrome.
- DNA based viruses are the ones that have DNA as their hereditary material. Example- Hepatitis B
- RNA is a molecule similar to DNA essential in the formation of proteins which are used for many integral reactions in every cell
- RNA viruses are found in two types: single-stranded RNA and double-stranded RNA.
- SARS COV-2 is a single-stranded RNA virus that causes the disease Covid-19
Core Principles of Molecular Biology
To understand SARS-CoV-2 in detail, we would have to know about the Central Dogma Of Molecular biology. It is a two-step process of how your genetic information encoded in the DNA/RNA (in humans its DNA) is encoded in the form of proteins.
The two steps are called transcription and translation.
- In this process, the message encoded in the DNA is copied on another single-strand RNA called the messenger RNA or mRNA
- The building blocks of this mRNA are small fragments floating around the DNA. Specialized enzymes take in those small blocks to build a chain called mRNA.
- This takes place in the nucleus of the cell
- Small organelles (organs of the cell) called ribosomes are present that assemble and join the small protein blocks called amino acids.
- mRNA travels out of the nucleus to the ribosome for this process.
- These amino acids are found in the free-floating cell space and brought together by another type of RNA called the tRNA.
- The tRNAs bring the specific amino acid which is linked together by the ribosome to form a polypeptide chain
The chain then is folded in different ways as per the requirement of the cell for its reactions.
Structure of the SARS-COV-2
Size- 50-200 nanometers (1 nanometer= 1×10-9 meters)
SARS-COV-2 is a spherical-shaped virus. The virus has 4 structural proteins that form its viral protein coat.
The 4 proteins are:
- S (structural)
2. E (envelope),
3. M (Membrane)
4. The nucleocapsid (a protein that is connected to the RNA)
What are the receptors?
Receptors are sense organs for the cell. They are present on the external layer/ cell membrane of the cell. These are responsible for sending signals to the cell and allow entry of various substances such as glucose, sodium, potassium etc. in the cell. Receptors act as communication channels between the cell and the outer world.
ACE-2 is the receptor which is present on the linings of respiratory tract is responsible for SARS-CoV-2
How does This virus replicate?
Viral replication is only possible when it takes place inside the host cell. In the case of SARS-CoV-2, it affects cells that form the outer lining of our respiratory tract.
It binds to the ACE 2 receptor on the cell membrane and facilities its entry in the cell.
The process is explained in the form of a flow chart
The new generation infects other cells in its vicinity in the same way and the process continues. RNA viruses have high rates of mutation and hence the vaccine produced would be for the current strain. Oxford University shows promising results of its vaccine of SARS-CoV-2 on monkeys.
Let us hope that the vaccine is released soon and the spread of this pandemic slows down and eventually stops.
Till then Stay Home, Stay Safe and maintain social distancing. Happy to answer your questions on the mechanism of the the virus on the human body.
Cheers and Best wishes
1. Mutation- change in the genetic structure either the DNA or RNA
2. Host- The animal or plant cell the virus invades
3. Replicate- To make exact copy of the genetic material