Electron Micrographs

Below are several electron micrographs that will help you review the lab material at home. But please note that these are just to jog your memory. The questions on the lab quiz will be from the actual electron micrographs and probably won't be the same as those shown below. You will want to develop the skills to recognize the structures in general.

As you observe each cell structure, be sure you can recall its general structure and function.

When you begin with a micrograph, first look for clues to help you grasp the level of magnification. The micrographs below, for example, have widely varying magnifications.

This first image shows the double walled nuclear envelope and rough endoplasmic reticulum with ribosomes. The chromatin inside the nucleus consists of the chromosomes, which are comprised of DNA and associated proteins.

The next image shows a cell that has very nearly finished dividing into two daughter cells. Note the microtubules that form the spindle apparatus. What is its function? Several mitochondria are visible.

Now observe a higher power view from the same micrograph that compares microtubules and microfilaments.

The next image is hard to visualize because it is a slice that just "grazes" the nuclear envelope. To the left, the slice is within the nucleus. But to the right it is slicing right through the two membranes of the nuclear envelope. Observe the nuclear pores.

The Golgi apparatus is challenging to grasp in our micrographs. But it is visible in several places. Usually Golgi apparatus does not look like the perfect "textbook" examples. Try to visualize the Golgi apparatus in three dimensions to understand how slices would look that angle through the Golgi in different ways. A top view, for example, might show only vesicles.

Here is a nice view of a centriole. Why are microtubules readily visible around it?

Finally, we have a very fortuitous slice showing a kinetochore. What is the function of this structure? Actually, a second kinetochore is visible, but not labelled. Can you find it? Notice also that the chromosomes are condensed into discrete structures since this is a dividing cell.