Using microscopes to see cells This is a compound light microscope, similar to the microscope you will be using in class. The specimen needs to be sliced very thin so that light can shine through it.

Using microscopes to see cells This is called a transmission electron microscope. Instead of shining light through a specimen, electrons are used. Because electrons are so much smaller than the wavelength of light, images created with electron microscopes are much more detailed.

Using microscopes to see cells The first two micrographs (think photograph from a microscoph), starting on the left, were taken using light microscopes. The third was taken using a flourescence micrograph. The fourth image was taken using a transmission electron microscope. Notice the small details, which are not captured using light microscopes. The final image was taken from a scanning electron microscope, which bounces electrons off of the surface of specimens instead of shining light through them. These produce amazing three-dimensional images.

Scale This image provides a perspective of scale when considering the size of cells and components with those cells. The following links are quick and fun. They also provide some perspective of size. http://learn.genetics.utah.edu/content/cells/scale/ http://www.cellsalive.com/howbig.htm

Cell Lab: draw and label on 400X Elodea leaf cells Cell wall, cell membrane cytoplasm, chloroplasts Homo sapien epithelial cells Cell membrane, cytoplasm, nucleus Allium epidermal cells Cell wall, cell membrane, cytoplasm, nucleus, nucleolus Solanum tuberosum amyloplast cells Cell wall, cell membrane, amyloplast These are the specimens we will be examining in our compound light microscopes. You are familiar with the water plant, Elodea from our experiments in ecology. The Homo sapien sapien cells will be your own cheek cells. The Allium cells will be onion cells. Allium is the genus that includes both onion and garlic. The Solanum tuberosum cells are potato cells. Amyloplast cells are specialized cells that function in storing amylose (remember the other word for amylose?). Amylose is stored in special structures within the cells called amyloplasts.

Eukaryotic Cells Have most of the same components as a prokaryotic cell Also have a nucleus and other membrane-bound organelles Model of a plant cell Model of an animal cell Compare the structure of a plant cell (left) to the structure of an animal cell (right). What structures do both cells have? What structures are unique to one cell or another? Most of the structures you observe in these cell models will not be visible when you observe plant and animal cells in a light microscope. We would need much more powerful microscopes to see these structures.

You will not add any kind of dye to your Elodea specimens that you examine, so the nucleus will be difficult to see. You should, however, be able to observe the chloroplasts easily, as well as the vacuoles. The vacuoles will look like empty spaces.

This is what happens to Elodea cells when salt water is added to the outside of the cell. Notice that the cell walls are still clearly visible and the cell membranes have shrunk inward, causing all the chloroplasts to clump together. Can you explain what happened and why?

After adding some dye to your cheek cells, you should observe something similar to this picture. Can you find the nucleus in any of these cheek cells? If you look carefully, you may be able to find a nucleolus as well.

These are onion cells. You should be able to find the cell wall and cell membrane (together), nucleus, and nucleolus. Onions are part of a plant, so why do you not find chloroplasts?

iPhone photo through a classroom microscope at 400X These are potato cells. Notice that the shape of the cells is different than the shape of the plant cells we have already looked at. Not all plant cells are shaped the same (nor are all animal cells). The blueish black clumps are amyloplasts (which store starch for the potato plant). iPhone photo through a classroom microscope at 400X