Thursday, October 8, 2009

Mother Mitochondria

In complex cells with organelles (little parts in the cell that have unique tasks in the cells activities, just like organs in your body), often there is an organelle called a mitochondria. Mitochondria is a fascinating part of the relatively modern cell.
Mitochondria is the part of a complex cell (whether it is a single cell or part of a complex organism) that processes glucose and turns it into energy for the cell. It can be compared to a powerhouse in the electrical grid, creating energy for all the other things to use so the whole system can operate. It does this by cleaving APPT into APP (look it up if you need). There are a few rare kinds of cells that have no mitochondria (using a different method to gain energy) which are often extremophilic. Generally though, the more energy a cell needs, the more mitochondria it has. For example, a muscle cell often has quite a few mitochondrian for the power it uses, whereas a skin cell which needs very little energy has only one which dies long before the cell is removed from the body.
There are a few interesting facts about mitochondria. Firstly, it is actually an archaebacteria that is living in symbiosis with the rest of the cell. That means it is actually an ancient bacteria that has been reabsorbed by the complex cell with other organelles for the mutual benefit of both the mitochondria and the cell. It has it's own DNA, separate from the rest of the cell's DNA. However, giving the rest of the cell energy in exchange for a more protected environment with more abilities in the cell is a good pay off for loss of autonomy. The arrangement has been in place for so long it would be doubtful if either the mitochondria or the complex cell could survive for long without the other.
Another interesting fact is that mitochondria is always passed down genetically on the mother's side. This is true also in single sex species as single sex species always function as female. You got your genetic print for your mitochondria from your mother and your mother's mother and so on to the first mitochondria that ever existed. So the way you break down (carbon based or organic) carbohydrates into energy is something you inherited from your genetic mother. Scientists have been using this DNA information to try and trace the "scientific Eve", or the first human female DNA strand. Although mitochondria is very useful in this as it is passed from women only, it is difficult because mitochondria DNA is highly changeable with rapid mutations occurring frequently. I think this happens because the DNA has experienced many extremes for a long time, so environmental factors such as eating/fasting, safe/unsafe, hot/cold, could set off the DNA switches to the best mode for survival. Also, since mitochondria DNA does not divide and share like a two sex system, I wonder why it is so changeable. I also wonder if, when the cell divides, if the mitochondria uses the simple cell mechanism of budding, or if the endoplasmic reticulum (ER) unzips the DNA as with the rest of the cell's DNA information.
Another mystery I wonder about is did the first complex (more the one organelle) cell have mitochondria in it's make up, or did the mitochondria be adopted or adopt later? Mitochondria definitely existed before complex cells, but when exactly did complex cells and mitochondria first team up? I would suspect that the agreement must have been between the nucleus and the mitochondria as they are both DNA carriers, although the endoplasmic reticulum (ER) does the DNA zipping and unzipping. As mitochondria are quite large, so I have difficulty picturing it invading a modern complex cell's wall (phospholibid bi-layer), so did it attach before the current cell wall took shape as it stands today? Are there free mitochondria today, floating about independently? Did mitochondria once sit on the outside of, let's say, plant cells that produced glucose, pushing them along to better spots (through evolution's survival of the most fitting) like a farmer with their livestock or crop?
Why did two entities with different DNA decide that the other was OK and and they would reside in the same cell as brain (nucleus) and brawn (mitochondria) without attacking the other as a foreign species? Could it be that the cells that were more co-operative did better and therefore proliferated? A cell that had the two DNA strands pitted against each other would have inevitably died (eg. put out a hormone signal that it was infected by a bacteria in a complex organism, and a killer T-cell {immune} would have destroyed and consumed it), or more rarely, removed the other's DNA (hence the cells with no mitochondria, often extremophilic, sometimes anaerobic, always less common).
Anyway, in conclusion, mitochondria is the part of the cell that uses carbohydrates in the form of glucose to create energy. So it is why we move and eat sugars, fats, carbohydrates and proteins (partly for proteins, because we use them for building our bodies, cells, and DNA a well). The mitochondria is about consuming energy so we can do action. It is also inherited on the mother's side and always has been. It is also a very old kind of bacterial cell from a long, long time ago. So they are responsible for the consuming of organic compounds for energy to actively move, which began with a complex cell working in conjunction with the mitochondria. As a microscopic mirror, is it like a mother feeding a child or a stomach supplying the brain, organs and limbs with energy? It is the reason why moving living things eat as much as they do. This tempts me to think about old mythology such as the role of humanity in the Southern African bushmen folklore or other Beginning or Where-We-Came-From stories around the world.

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