…it’s a very good place to start. (by Samuel Waldron)
OK I will skirt round all the stuff about what came before the single-celled organism or we could be here all day. Basically I want to start small and get bigger. I mean in terms of the size of the subjects I will initially write about. I will inevitably get to the behavioural side of things as well as the physiological aspects of zoology, but I must practice what I preach and start by talking about small things.
The reasons (the preaching), I have outlined on the page about-the-zoological-blog and, for me, make complete sense! Cells are the classic small thing for a Biologist. What goes on inside and around them are often too small to consider. Why this is for the Microbiologists!
But, what goes on in and around the cell is equally if not more fascinating and in some way or another they all go on in every walk of life, so they must be important, no? There are three basic branches of life, bacteria, archaea and Eukaryotes. They have evolved in this order, the simplest form of cell comes first (bacteria), a prokaryote (single-celled organism) consisting of no internal compartmentalisation. By this I mean no organelles, no nucleus or ribosome’s, all the organisms’ contents are floating around within a membrane and surrounded by a cell wall. The Archaea branch comes next, another form of prokaryote, this time the processes within the cells are more closely related to the eukaryotes.
Although it is difficult to distinguish between bacteria and archaea species from the outside, the mechanisms within make it more clear. The processes the archaea use to handle important genetic information (DNA and RNA) are similar to the eukaryotes. Conversely, the production of energy and the way it is used by the archaea seem to be more closely related to the bacterial branch. Does this suggest or show the path taken from simplest to the more complex forms of cells? Most would say YES!
So what was I talking about…oh yes the interesting things that go on inside and outside the cells. Take our cells for example, they make up our body. This overall structure, mass of cells is what defines a Eukaryotes. An organism made up of more than one cell and more often than not a host of different cells doing different cell things. We have liver cells, nerve cells, brain cells, etc. etc. they all look very different and have very different roles within our bodies, however they all have something in common. Another important characteristic of the evolution towards greater complexity is compartmentalisation. It is like the Monica factor in the T.V. series Friends; I make this comment in jest. For anyone who knows the character they will know she is always filing things, putting things in order, categories for red, green and blue folders each have a different subject, they can be cross referenced with big, small and medium sized yellow folders and can then be arranged alphabetically in accordance with…ok you get the idea, (anyone know a good episode to highlight the Monica factor please let us know).
What I’m getting at is by putting things into a compartment is basically putting things into an order. By putting all the DNA of a cell into the nucleus it is becoming organised. Anything that wants to communicate with the DNA must ask the relevant people (in the case of the cell-receptors). This goes for all the organelles within a cell. The endoplasmic reticulum and golgi apparatus organise the production of proteins. The mitochondrion is in charge of the energy production. The cell membrane is the gatekeeper and in most part receives signals from other cells and restricts the flow of materials in and out of the cell. This is it, this is the interesting things that go on in and around the cell. In the cell you have lots of different little soap operas going on between the organelles. You have movie sets, where the main stage is the surface of the cell. The stars of The West End are the proteins, fulfilling there roles, not always perfectly…but they try. All this in one type of cell…only one type of cell!!! What is going on in the others, who are the stars what is their role. That is it, I must get the next issue of LOOK, no no HEAT noooooo NUTS…go on get a copy of Nature https://secure.nature.com/subscribe/nature
Comments are very welcome 🙂
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