A few days ago I came across a very interesting video on YouTube about neuron culture. Neuron culture is part of science called cell culture which involves growing cells outside the body. Neuron cells are extracted out of mice brain and then grown into an artificial environment. The environment is generally a solution which provides all necessary nutrients to the neuron. This is interesting but there is something else that blew my mind.
Fast forwarding to the 6th minute of the video, the researcher talks about how neurons start making connections with each other within a week. At first it was a shock. Why? Well, I used to believe that neurons make connections only inside human skull. Light hits retina. Electrical pulses are sent to brain through optic nerve. Neurons are excited by these signal and they start passing it on, by connecting with each other. That was my mental visualization. That obviously meant that all experiences are bunch of neurons firing in a certain way, in a pattern. Ergo, pain is a pattern, sweet taste is a pattern and every thought is a particular pattern. Then why do these neurons in an artificial environment make connections? What is stimulating these neurons?? This means neurons have a life of their own and a purpose that they carry out no matter what their host environment is. Somehow, I started wondering- what is life? What does death mean, chemically?
This whole thing got me interested in single cell organisms like amoeba or algae. I wanted to know what makes a cell alive. I started reading about microbiology. Most single cell organisms have a lot in common. They eat, reproduce, excrete, grow and they have a cell body. But are these features absolutely necessary to label something as a Living thing??
Well, meet Viruses. They don’t have a cell body. They aren’t active until they find a living cell like another bacteria or any other cell for that matter. It’s not clear whether to call them living or not. You will see many articles referring to viruses as particles. You can not call them non-living because Viruses do have genetic material with them. They hijack a cell and then they replicate. This is where we deal with gray area of life. Eventually, you start wondering, when does chemistry become biochemistry?? What is the threshold? Why do particular proteins replicate?