Cells

This week, for biology, we learned about cells. We have been watching some of the videos here, and we watched two movies about cell death (Death By Design and The Life and Times of Life and Times, as mentioned in the previous post.) We decided to look at some different things under our microscope.

First, we looked at an onion skin. We took two pieces from the bottom layer of an onion, and we put them on two different slides. With one, we put some Iodine on the slide so we could see the different layers, and the other we didn't use Iodine on. Here are some of the pictures we took:

The slide without Iodine at x100

The slide with Iodine at x100

Onion Cell Lab Instructions.

1. Add 2 drops of iodine to the center of a glass slide. Be careful! Iodine can stain your clothes.
2. Take a small piece of onion. Use tweezers to peel off the skin from the underside (the rough, white side) of the onion. Throw the rest of the onion piece away.
3. Carefully lay the onion skin flat in the center of the slide on top of the iodine.
4. Add 2 drops of iodine to the top of the onion skin.
5. Stand a thin glass cover slip on its edge near the onion skin, next to the drop of iodine.
6. Slowly lower the other side of the cover slip until it covers the onion skin completely. If there are air bubbles, gently tap on the glass to “chase” them out.

The second lab we did was our fishtank plants. Having two tanks we took a sample from both, it was quite simple to set up, we merely put a small leaf with a couple drops of water on a slide. Photos below:

Leaf cell plant at x400

Leaf at x40

Plant Cell Lab Instructions

1. Tear off one small leaf/stem from the plants in the fish tank.
2. Add one drop of tap water to the slide.
3. Stand a thin glass cover slip on its edge near the leaf, next to the drop of water.
4. Slowly lower the other side of the cover slip until it covers the leaf completely. Make sure there are no air bubbles.

The last lab we did was human skin cells. This was an interesting lab to do, we looked at three different samples of cheek cells, though there wasn't much difference between the cells. Photo:

The cheek cells at x400

Human Cheek Cell Lab Instructions

1. Add one drop of methylene blue to the middle of a clean slide. Be careful! Methylene blue will stain your clothes and skin.
2. Use the flat side of a toothpick to gently scratch the inside of your cheek. DO NOT GOUGE YOUR CHEEK - you don’t need chunks of skin and definitely don’t want to draw blood.
3. Gently touch the toothpick to the drop of dye on the slide. Some of your cheek cells should drift off into the dye.
4. Throw the toothpick away.
5. Stand a thin glass cover slip on its edge near the drop of dye.
6. Slowly lower the other side of the cover slip until it covers the dye completely. Make sure there are no air bubbles.

Links:
My Science Box (Source of experiments)