Page 3 - Dream May 2020 English

COVID-19 SPECIAL
THE ENEMY
I am inept. I cannot make babies on my own. What is life, if you cannot produce and nourish the next generation? I just have my genetic code RNA. But no reader, no copier. I am like a book without a reader.
I lack the cell organelles that you have-- which means I cannot produce any proteins or make copies of RNA on my own. This leads to the second shortcoming. I cannot do without your cell. You can live without me, but I cannot live outside your cell. I need you more than you need me. I need to enter and hijack your cell. Only then, I can live and reproduce.
But unlike say, your gut bacteria, which lives in a helpful relationship, I am a parasite. I enter your body in stealth and steal your cellular machinery for my ends. I give nothing in return.
You are my recent host
My progenitors were living in the bat. They lacked the crucial protein part to bind with human cells. Hence, they were never able to enter the humans. Like your ancestors came down from trees, evolved, and walked on two legs, one of my families made a significant shift. It jumped from bat to another animal. Which one, we do not remember. Your researchers are in the lookout for this intermediary. Sometime in the past, as part of the natural evolution, one of our predecessors hit the jackpot. They accidentally got the 'key' to open a lock on the human cell. Since then, because of this critical change, sometime around last November 2019, one of my family members took a bold step. It leapt to humans. Then there was no turning back. Since then, I have been living by leeching off humans.
The pivotal change that took place was in my spike protein. A mutation on the genetic code for the spike protein, to be precise, insertion of 12 genetic letters, ccucggcgggca, changed my fate, as well as yours. Due to this mutation, the shape of the spikes altered to bind with the human cell, in particular with a receptor called angiotensin-converting enzyme 2 (ACE2). This was a crucial step in our evolution from being a virus that infected the bats to be a virus that blight the humans.
Backdoor
The ACE2 receptors are copiously expressed in the epithelial cells in your nose, respiratory tract, lungs and stomach. You can think of a receptor as a lock. When a protein with the right shape and structure approaches and docks, it can bind.
By comparing the genome sequence, scientists can determine the evolutionary path. From these studies we know that this virus is not human-engineered
With that fortuitous mutation, accidentality the form of my spike protein moulded to fit your receptor. I could use it as a counterfeit key to unlock the backdoor.
Khul Ja Sim Sim. I was snapped tight into your respiratory tract cells. The cells on your skin lack this ACE2 receptor. That is why we need to reach your eyes, nose or mouth to gain entry into your respiratory tract. Your natural habit of touching your face, picking your nose and rubbing your eyes, all help us; we love them.
By the way, typically, your ACE2 receptors play a crucial role in controlling blood pressure. That is why people who have high blood pressure, diabetes and heart disease are more susceptible to my axe.
Once we latch on the receptor, the transmembrane enzyme, TMPRSS2 on your cell membrane lends a helping hand. This enzyme, a protease, cleaves, and activates the viral spike glycoproteins and facilitates my layer to fuse with your cell membrane. I slowly sink into your cell.
Cellular cafeteria
One can imagine the working of a cell as a restaurant. A lung cell differs from a skin cell like a Chinese takeaway and a south Indian eatery. Each type of cell can be thought of as specialising in different cuisines. The DNA is the set of instructions for the cell, which tells it how to make various proteins, how to fold them when to make them, where to send them. You can imagine the 23 pairs of chromosome DNA as a giant recipe book containing instructions for making various delicious dishes. From masala dosa to aviyal. From milagu
The mRNA is sent out by the nucleus with a set of instructions. Following them, the ribosome produces proteins. The
proteins are processed by the Golgi apparatus and the
protein package is sent to various parts of the body.
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