So I guess everyone might have heard of the science pyramid right? It's like a hierarchy that organises different basic science disciplines into order, something like the image below:
The hierarchical order of science
So we have mathematics as the basis of everything. It's like the language of nature. Then we have physics, the almighty disciplines that everything we know in this universe has to obey its laws. Physics use maths as its language to describe every physical phenomenon, from how a pendulum moves to how photon travel in space, just think physics is applied maths basically. Then we have chemistry above physics, the science studies the conversion of molecules from one to another. Every law of chemistry must obey the laws of physics. From how salt dissolves in water to how electrons jump from one atom to the next, chemistry is considered to be the bridge between the world of the livings and the world of the inanimate, it's a central science. Then finally we arrive at biology, a specialised discipline studying the diverse world of living organisms.
It really isn't a coincidence that biology is sitting at the top of the pyramid. Living organisms are the miracle of nature, a bunch of dead stuff come together and life as we know it emerged! Even though biological systems have their own properties, those that don't exist at lower levels (scientists called these properties emergence, like how a school of fish can move in such coordination to hunt and to avoid predators), they do obey every law of physics and chemistry and their behaviours could be modelled with maths, even if it can be very complex. So to study biology, we really need to intercalate all the knowledge we know from maths to physics to chemistry in order to understand biology.
So I was always fascinated by these beautiful machineries, but at the molecular level. Because to understand a machine as a whole, you need to know what its components do, right? This is why biochemistry captivates my curiosity the most. So Biochemistry sits somewhere between chemical science and biology because after all, living organisms are just another complex chemical machines. I don't just want to know why a bone look the way they are or how your digestive system works? But I want to know what makes up your bones or what digest your food? How does this work? And what happened to individual molecules that were being digested? The tiny biochemical machines inside your body that carry out all these important works are proteins. The thing that really digests your food are enzymes, they are proteins too. Those that allow you to taste the sweetness of that chocolate cake on your tongue are tastebuds, which are also proteins. Even those molecules that control the flow of water in and out of your cells are proteins too, which are known as aquaporins. To me, the beauty of biology really lies at the molecular and atomic scale.
Yesterday I was just sitting on my own rewatching some animation on how the electron transport chain work and till this day it still blew me away at how intricate these networks are.
Complex I of the Electron Transport Chain (PDB-ID: 5LDW)
Just look at this magnificent protein complex. I hope you can appreciate how detailed and intricate it is. This is what a protein looks like if it's big enough for your eyes to see! How amazing! These proteins have evolved over millions of years to the point they can control the movement of individual electrons inside them by using different electron acceptors with increased affinity. This makes sure that the electrons can only flow in 1 way only! The energy released from the jumping of electrons could then be harvested to pump H+ across the membrane. Just think about it for a second! These proteins can control the movement of electrons and H+, which are actually individual proton! Remember in quantum mechanics, electrons aren't just a round spherical ball like you might imagine. These entities exist like cloud, waves of probability that physics have taught us, they can exist at two places at the same time and can create wave pattern for goodness sake! Yet these proteins could control the flow of these tiny "particles", 1 at a time.
Then we have enzymes like serine proteases like those found in your intestine that can cut proteins up. They use their amino acids at their catalytic site to act like a pair of atomic scissors, carefully hydrolyse the protein up with the help of 1 molecule of water at a time.
One might have heard of protein cutting protein up, but what about DNA? Cas-9 protein, for example, can catalyse the hydrolysis of the DNA backbone. This is the protein that has made a storm in the molecular biology field because it's a part of the CRISPR-Cas9 genome editing tool kit. The protein itself has its binding site that specifically can recognise certain architecture on the DNA molecule, using a molecule of water to hydrolyse the phosphodiester bond linking the nucleotide together. You can clearly see that process in this video here: https://www.sciencemag.org/news/2017/11/watch-crispr-edit-genes-real-time
I just absolutely adore this. To me, this is the epidemy of science, understanding how a biological systems work, down to the single atom, how it changes its shape, its properties to perform its functions. I don't think you can find anywhere such an intricate masterpiece like that, nowhere in any other science disciplines you can find molecular machinery that can modulate the flow of individual molecule of water or electrons like in biochemistry. To understand this, you really have to bring all the science together and that just makes its such a beautiful combination to be a part of. The next time someone asks you what's your favourite science disciplines, I hope you could take a moment to consider saying "It's Biochemistry".
Until next time :)
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