Here’s the thing. In the first three generations of life, bacteria are a very simple cell that is a single bacterium. There are only two other bacteria on the planet, but then we start branching out and the number doubles. In the second and third generations of life, the branching increases to 256. The numbers of bacteria then quickly approach millions.
This is an example of how the numbers of bacteria don’t always add up. Many bacteria are able to change the number of cells in their body without much difficulty. But bacteria are not just a single bacterial cell, they are the building blocks of all life. The numbers of bacteria in my body are just a few billions, but in my brain a single bacterium makes up a tiny portion of the neuron.
This is one of the reasons we can think of bacteria as “cells” in our bodies. The actual number of bacteria in our bodies is quite small. Most bacteria are found in our intestines and our skin, but we can go as far as to say that there are trillions of them. As I’ve said before, the human body contains billions of these tiny micro-organisms. It is not the case that our body contains a single bacterial cell.
The way bacteria grow and replicate is completely different from how cells grow and replicate. We can look at the microscopic structure of bacteria, and we will find it very similar to the structure of cells. But bacteria that are in our bodies are not cells or cells that are not in our bodies. They are the smallest, simplest, and most primitive kind of organisms.
What about the cells that are the smallest and most primitive kind of organisms? What do they look like? The only thing that is really in their cells is their cell surface molecules. This means that the cells aren’t formed by the molecules that are in their cells, they are formed by many different molecules. The only exception is the genes that are the genetic “mechanisms” that are the genetic basis of the organism’s survival.
Cells are the building blocks of all life on earth. If you have a bacteria cell, you have a cell. If you have a plant cell, you have a cell. If you have a human cell, you have a cell. If you have a starfish cell, you have a cell.
Cell surface molecules are just some of the unique properties of life. Different cells have different surface molecules, and those differences are what give them the uniqueness that they have. The bacterial cell has different surface molecules than the mammalian cell, and the mammalian cell has different surface molecules than the starfish cell.
The human cell is one of our oldest cells. The oldest cells of any organism are those that are the cells of the human body. And we can be pretty sure that a single bacterial cell is one of the oldest cells we’ve ever seen. It was discovered in 1909 by Italian microbiologist Luigi Galvani.