Plant and animal cells

Republic of Panama

Minister of Education

Plant and Animal Cells

Due Date: 08/04/11

Introduction:

In this investigation we will examine the two most common types of cells, plant cells and animal cells. We will see from the onion skin cells to the green algae cells and the blood of frog cells. It is predicted that all cells, no matter if it be plant or animal, will be in beside eachother in large groups, that most of the major organelles will be visible through the microscope. The cell is the most basic unit of life and knowing about it will help us answer many different questions. If someone knows about the cell and how it works they could find a way to counteract viruses and illnesses, thus creating medicine and a way to cure the virus or illness. Without knowledge of thecell, we wouldn’t know about how we get our energy, how we use our five senses or even how we exist. We should know about the cell because it helps us understand that every cell has an individual job to fulfill and those cells let us do what we can do now.

Objectives:

* Students will discover the different cell organisms on different plates. Students will discover that onions are made upof cells. Students will observe onion cells under microscope. Students will discover that their skin is made up of cells. Students will observe cheek cells under a microscope.

* The purpose of this lab is to learn how to prepare a wet mound, to learn proper staining techniques and to examine human cheek cells and onion skin cells.

Materials:

* Microscope: An optical instrument thatuses a lens or a combination of lenses to produce magnified images of small objects, especially of objects too small to be seen by the unaided eye.
* Iodine Stain: Used as a starch indicator. When in solution, starch and iodine turn a dark blue color.
* Methylene blue stain: Stains animal cells to make nuclei more visible.
* Two cover slips: a very thin piece of glass placed over aspecimen on a glass slide that is to be examined under a microscope.
* 3 Different Plates: A plate containing green algae, another one containing paramecium and the last one containing frog’s blood (animal’s blood).
* An onion
* And a toothpick

Procedure:
Onion cell:
* Peel off a small section of onion skin.
* Place the onion skin in the centre of the slide.
* Place thetwo drops of water on the onion skin. This is called a “wet mount”.
* Starting at one edge, gently lower a cover slip over the onion skin.
* Gently tap the slide with a pencil to remove any air bubbles.
* Place a drop of iodine at one edge of the cover slip. Touch the opposite edge of the cover slip with a paper towel to draw the stain under the slip.
* Place the slide on the stageunder low power. Use the coarse adjustment knob to focus. (At minimum you should observe the nucleus, cell wall, and cytoplasm).
* Rotate the nosepiece to medium power. Use the fine adjustment knob to focus. Observe what you see.
* Repeat step 8, but this time switch to high power and draw what you see (use a pencil).
* After you draw your diagrams, rotate the nosepiece back to lowpower. Remove the slide and dispose of the piece of onion, and wash the slide and cover slip.

Microscope’s Example:

Cheek Cell:
* Put a drop of methylene blue on a slide. Caution: methylene blue will stain clothes and skin. And make sure it is specific for animals.
* Gently scrape the inside of your cheek with the flat side of a toothpick. Scrape lightly.
* Stir the end of thetoothpick in the stain and throw the toothpick away.
* Place a coverslip onto the slide.
* Use the SCANNING objective to focus. You probably will not see the cells at this power.
* Switch to low power. Cells should be visible, but they will be small and look like nearly clear purplish blobs. If you are looking at something very dark purple, it is probably not a cell.
* Once you think...