Looking at Cells

11/09/2010 § Leave a comment

Having finished the first unit (Biochemistry), our class immediately started our next unit, which is Cell Organization. For this unit, our essay question relates a cell’s structure to its function: Within the context of cellular structure and function, describe and explain how form relates to function. In terms of what we’ll learn this unit, we’ll have to describe how something’s structure tells us something about what it does. To state a very tentative and vague example; if we look at the cells of heart organ, we should be able to tell that the cell helps the heart in some way by its structure.

Or something like that.

I’m pretty sure that that’s the idea of the essay question for this unit but I can’t be sure. We’ve only started the lesson of Looking at Cells and nothing much else.

We (scientists, students and teachers) look at cells through magnificent instruments called microscopes. This is basically what we learned about through-out the entire class. The history of microscopes start somewhere during the middle of the 17th century (circa 1650s). The people of the time discovered that if they curved a piece of glass and looked through that curved piece of glass, they would find that what they were looking at was magnified. Maybe the specimen wasn’t magnified as much as specimens are magnified today but they could see the object much larger than it is in reality. Robert Hooke was the first to look at a cork under the light of a flame (since there was no electricity back then). By the time the 19th century arrived, microscopes got much better and scientists could actually see all the cells that make up organ and organisms.

Then the class learned that there are two kinds of microscopes used today: light and electron microscopes.

Light microscopes and electron microscopes have their separate advantages and disadvantages. For example, light microscopes have something of a greater advantage because they show the specimens in color. With color, scientists (or students, in our case) have a factor or characteristic to add to their observations and sometimes, color is very important in a study. Plus, experiments where color is involved help greatly, too.

Light microscopes are also much cheaper than electron microscopes and are easy to move around; they’re portable. Light microscopes also magnify up to 2000x and resolve to 200nm. They also have a bigger field view and can observe living organisms. In observing living organisms (as we witnessed in our most recent lab experiment), we can watch their behavior and make note of what the organisms do every day.

Ayushi then asked after Mr. Ferguson pointed out all of the advantages of a light microscope: “Then what’s the point of buying an electron microscope when light microscopes are so good?” Actually, electron microscopes also have their advantages. Although they’re incredibly large, barely portable and hugely expensive, (not to mention that they don’t even show the organisms alive nor in color), these microscopes can magnify a specimen up to 200,000x and can resolve the image to 1nm, meaning the observer will be seeing the specimen very clearly. If the resolution is not very good, then it is low and things will look as if they’re attached. But if they’re resolution is high, like in an electron microscope, then things will look separate, as they’re supposed to and an observer will see light between each specimen.

Although I’m not very solid with this part of the lecture, light waves, which are about 400-700 nanometers in size/length (depending on how powerful the light wave is, I think), are too big to flow through some specimen, so the electron microscope instead uses electrons (which use electricity) to bounce off the metal-covered-specimen and give off shapes and the general outline of the specimen. All in all, this process works so well that it’s as if a scientist is looking at a magnified specimen perfectly.

There are also 3D versions of the electron microscope, which is the SEM (scanning electron microscope), and the specimen is tilted so that an observer would be able to see all parts of the specimen, even if it’s dead.

So, basically, right now we’ve only been introduced to the entire unit but I’m sure that in a while, I’ll be able to make more connections for our essay question: How does form relate to function? (basically).

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