spectacular cells
Posted: Thu Nov 29, 2007 12:55 pm
This was a subject that I came across. This is not a subject up for debate, but rather an insight. Anyway, here it is. Imagine it is a hot summer day and you have spent too much time in the sun. Perhaps you are a little red or even badly sunburned. Over the next few days, an amazing process takes place as your body heals itself from overexposure to the sun. No doubt, you paid more attention to this process if your skin got to the point of peeling or had become red and sensitive. But look at it from another angle-the amazing adaptability of skin. Through several processes, your skin is shedding its damaged cells and replacing them with new, healthy ones. Your entire body-from your skin, to your eyes, organs and brain- is made up of cells. In fact, your body consists of over 250 different kinds of cells totalling about 100 trillion. So efficient and effective are these "little factories" that in 7 years, your body will have completely replaced all 100 trillion cells! The design of each of those 250 types varies in shape, size, density, and purpose. The inner functioning of the cell is most fascinating. You can think of any cell as a miniature factory, and it is MINIATURE! Red blood cells, for instance, are 10 times smaller than the width of a single human hair. Yet, even though each individual cell is microscopic, if you placed all the cells in your body end to end, they would encircle the earth 200 times! So far, we are only talking about the size of the cells, never mind their function! Cells are made up primarily of 3 parts, membrane, cytoplasm, and nucleus. The membrane surrounds the cell, and has the ability to recognize hundreds of substances. Acting as a "traffic cop", it controls what enters the cell and what is purged. The cytoplasm is the cell's "factory floor" on which there are thosands of machines called organelles. At any given time, there are over 20 different chemical reactions happening in the cytoplasm, for such purposes as communcation, waste removal, repair, nutrition, and reproduction. There is even an elaborate transport system to move products and waste throughout the cell. While all this is certainly remarkable, it gets even deeper. All of these functions are controlled by the "brains" of the cell-the nucleus. The nucleus houses all the information that the cell needs to repair and reproduce itself. This blueprint is made up of chromosomes and genes containing DNA. When properly understood, DNA is one of the most breathtaking creations in the entire universe. In an age where computers are getting smaller and smaller, you may be amazed at how tiny complex gadgets have become. However, all these PALE in comparison to DNA. If you transribed the genetic information for just ONE person onto paper, it would fill a 300-volume encyclopedia set, each volume consisting of 2000 pages. DNA is stored in an amazingly "spiral staircase". This is so effective in conserving space, thart if you were to unravel this spiral from any human cell, it would be about SIX FEET in length. In fact, it has been estimated, that if you placed all the DNA in the human body end-to-end, it would reach to the sun and back 400 times! Yet, all the genetic information needed to replicate the over 6 billion people on earth today could fit into an area of about 1/8 of a square inch! The nucleus cellular membrane and all the machines in the cytoplasm make up every cell in your body. Now stop for a moment and recall that there are 100 trillion cells in your body, all with these little machines, factories, and "supervisors" constantly working and reproducing. Truly the human body is amazing! Here is the incredible fact about the largest and smallest cells of the body: Both are the "bookends" for creating life. The smallest cell is the male sperm cell. At the other end of the scale is the female egg cell. All cells, and therefore all life, fall between these cells in size. But to create life, the largest and the smallest cells combine. It is interesting that the two most important cells of all are the largest and the smallest, with all the rest falling in between. Coincidence or DESIGN?
The biology teacher isn't at all biased though 
)
I knew you wwere a teacher (previous post) but not biology! This should be right up your alley then. I got a few others to post later, too.