This article is a biology summary that my teacher asked us to write at the end of last semester. I didn’t want to make it too rigid, so I decided to have some fun with it... I hope it serves as a reference for your biology studies. Please feel free to share any suggestions!
Whenever we sit before a mirror and examine ourselves closely, we discover how ordinary we are, yet how many unique qualities we possess. Even when looking at the broader natural world, we are both commonplace and “extraordinary.” We also have another name: Life.
We humans, along with all other forms of life—whether bacteria, fungi, animals, or plants—do not possess any unique elements. That is to say, the elements flowing within us can all be found in the natural world. This is the unity between the biotic and abiotic worlds, reflecting our “ordinariness.” However, within this ordinariness lies “extraordinariness.” There are also distinct differences between the biological and non-biological worlds; although our elements can be found in nature, their concentrations are vastly different. Perhaps this is the mark left by the “Creator” to distinguish the living from the non-living!
In the eyes of physicists and chemists, we are composed of molecules and atoms. But in the eyes of biologists, the “basic unit” that constitutes us is the cell—a thing larger than a molecule that also possesses life. All living organisms are made of cells, and the cell is the fundamental unit of life activities.
Let us connect our optic nerves to an electron microscope and use these “eyes” to observe a cell. “Oh my god! This is amazing!” I think everyone would instinctively cry out in such wonder. We marvel at the rational construction and orderly nature of the cell, at the exquisite craftsmanship of nature. Inside this tiny cell lies a high-efficiency “factory”! Surrounding the factory is a “perimeter wall” (the cell membrane) built of lipids and proteins; it separates the “factory” from the outside world and acts as both a telephone and a security guard. The “factory” is filled with a substance called cytoplasm, composed of water, hydrated inorganic salts, and other materials. Only in this environment can the “workers” perform their tasks efficiently. The “energy workshops,” known as mitochondria, are distributed throughout the cytoplasm. In plant cells, there is also a “manufacturing workshop” called the chloroplast. Mitochondria and chloroplasts share a common term: organelles. Besides these two, there are other organelles such as ribosomes, the endoplasmic reticulum, and the Golgi apparatus. Each plays a different role, making the cell as captivating as a Hollywood blockbuster!
The CEO of the factory, or the processing center, is what we call the “cell nucleus.” This is the control center for cellular metabolism and heredity; in other words, it decides what the cell should and should not do, and what the next generation will look like. As a side note: there are two types of cells, eukaryotic and prokaryotic. Eukaryotic cells have a complete nucleus, while prokaryotic cells have only a “nucleoid,” which is a nucleus not enclosed by a nuclear membrane. Returning to the genetic material within the nucleus, it consists mainly of DNA and RNA. The primary genetic material of life is DNA, though some forms of life, such as influenza viruses, are special and use RNA as their genetic material. DNA and RNA are not only found in the cell nucleus; small amounts are also present in mitochondria and chloroplasts.
Various substances in the cell undergo reactions efficiently within this factory with the help of enzymes. Enzymes are quite remarkable; in chemistry, they are known as “enzymatic catalysts.” They do not provide energy themselves, but they lower the activation energy required for chemical reactions, and they are highly specific and efficient. Cellular respiration, photosynthesis in plants, and many other processes would be impossible without the support of enzymes. Imagine if, without the help of enzymes, a chemical reaction had to be heated to several hundred degrees—how could a cell possibly survive that?
Our journey is now drawing to a close. There are still many diverse topics within the cell waiting for us to explore. Even a single tiny cell contains such strange and wonderful mysteries. It is clear that a biological organism is a massive and complex process; calling life nature’s greatest masterpiece is no exaggeration at all!
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