I was researching oxygen, and I found out that there is a substance that is essential for living things, called the energy currency of cells. Adenosine triphosphate (ATP) apparently stores and releases energy within cells. All living things run on the energy generated by the decomposition of ATP. ATP is used for everything, from movement, chemical reactions in cells, the five senses, and DNA replication, and is like a currency that can be exchanged for energy, so it is called energy currency. ATP is amazing.
https://www.kyoto-su.ac.jp/project/st/st11_06.html
Once broken down and the energy is extracted, it is converted back into ATP through food or other means. Apparently, humans only have enough ATP for 180 seconds, but this is met by a cycle of decomposition and synthesis. There are two types of ATP production: aerobic energy metabolism, which uses oxygen, and anaerobic energy metabolism, which does not. The key to this metabolism is mitochondria.
https://www.e-healthnet.mhlw.go.jp/information/exercise/s-02-001.html
It’s amazing that ATP can be produced even in conditions without oxygen, such as underground or underwater microorganisms. Plants also produce ATP through photosynthesis during the day and break it down at night. The key to this photosynthesis is chloroplasts. It seems that mitochondria and chloroplasts have something in common, both in terms of their roles and existence.
https://www.rd.ntt/se/media/article/0089.html
The mitochondria and chloroplasts that produce this energy currency, ATP, are now inside cells, but they were once separate organisms. 1 to 2 billion years ago, other organisms entered cells and became organelles. Proteobacteria lived in the mitochondria of animal and plant cells, and cyanobacteria lived in the chloroplasts of plant cells, forming an intracellular symbiosis (primary symbiosis).
https://www.titech.ac.jp/news/2015/032688
https://blog.miraikan.jst.go.jp/articles/20181221post-68.html
This endosymbiosis seems to be a rare event that occurred over billions of years in the history of the Earth, with mitochondria 2.2 billion years ago and chloroplasts 1.6 billion years ago. It’s a mystery how it got there, but perhaps at some point a life system capable of utilizing ATP was born. This common energy system, shared by animals, plants, and microorganisms, is probably common to the whole Earth. ATP is amazing. The Earth is amazing.
