How does a cell know what to do? How does it know where it is? How does the cell know it belongs? Well...How do you?
Let’s imagine a typical morning, an ordinary routine for many of us. As you are getting ready to start your day, whether it is school or work, or any other responsibility you are about to take on, you stand in front of the mirror and look at yourself. Is my hair okay? Do I look presentable? I need to brush my teeth. I should hide my dry skin and puffy eyes. A shower. Clean clothes. Should I wear this neon pink sweater? Perhaps it is too much. I got a lot of attention last time I wore it and I felt as if I am in the spotlight. Awkward. Let’s go with something more acceptable. Beige will do. Better polish my shoes. Put some perfume on. Last check in the mirror. Good to go.
The obligatory “hello’s” and “how was your weekend?”. You are polite. Not that necessarily you enthusiastically care about your fellow colleagues’ mundanities. No. Not at all. But naturally you feel as if that makes you part of the normality. That is just something you do to...belong. The lunches, chit-chats, and nods, awkward smiles and handshakes and eye contact. Too much? Weird. Not at all? Weird. Wrong. It is in the social nuances, the art of balancing between politeness and distance, being involved and minding your own business. Having an opinion but constantly checking whether it is okay to think that way by receiving the influx of acceptance or rejection waves from the society. Being confident but not too much. Like an acrobat balancing on a string to perform in front of the audience. One wrong move and it could result in a disaster. A risky and right move? Gasps and applause.
The microscopic world is almost identical to the macroscopic one. Just like you check whether you “fit in”, so do cells.
Let's take the example of a heart cell- how does it know that it indeed is a heart cell? Well, it is called cell-to-cell communication, and that is an essential function of all living organisms. In order to perform the correct duties that a specific tissue requires, the cell has to have a language that lets it check its normality. The language they use is a bit different from ours, instead of words and gestures and facial expressions, cells use chemistry to communicate. They send signals to each other that let them know they are in the right place. The previously mentioned heart cell sends a signal molecule that is a protein or other molecule, like a message in a bottle, and the receiving cell has to have a receptor that can receive and interpret this ‘message’. Then it will send a message back “Hey, you are okay!”. The signaling molecule is oftentimes called a ligand that, through the extracellular space, travels to the surrounding target cells. This leads to a chemical change in the cell receiving the ligand, which leads to the interpretation of the message. If everything is alright- the cells know, chemically, that they understand each other, thus, there is an optimal function in the tissue. In case the surrounding cells do not have the right receptors or the signaling molecules lead to incorrect chemical change in the target cells, that initiates a process called apoptosis or “cell
death”- elimination of the wrong cell that is produced by the signaling cell itself. Sometimes the cell can decide not to perform “cell suicide” and those are malignant ones, also known as
The parallel between our way of communication and self-reflection in the grand scheme of society and that of the cells within us, is fascinatingly close. Every living organism, no matter how big or small, smart or primitive they are, all belong to a system that is self-regulating and every component is necessary for it to work and exist.