Investigating Cells Lab. 1. What major differences do you expect to see between bacterial cells and plant/animal

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1 Investigating Cells Lab Name 7 th Grade PSI Questions: o How do you use a microscope? o What do bacterial cells look like? o Are there any visible differences between plant cells and animal cells? o What organisms can be found in pond or fish tank water? Hypothesis Starters: 1. What major differences do you expect to see between bacterial cells and plant/animal cells? Purpose This lab will help you to learn how to use a microscope and observe different types of cells. A microscope is one of the most powerful tools in science and has allowed us to learn about a whole new world of organisms that can t been seen with the naked eye. Cells are the fundamental units of life, and all living things are made out of cells. This lab will show you what different types of prokaryotic and eukaryotic cells look like and hone your observation skills. Materials and Directions: Compound microscope 3 Blank microscope slides 1 Deep-well microscope slide 4 Blank cover slips Water and water dropper Prepared slides of bacteria Cut-out of the letter e 12 pt. Times New Roman font Toothpick Iodine Animal cheek cells (from your mouth, be careful)

2 Elodea leaf and forceps to pick it up Sample from pond water or fish tank water Pipet or dropper Procedure Part I: Magnification observations 1. Cut out the letter e and place it on a flat microscope slide face up. 2. Add a drop of water to the slide 3. Place the cover slip on the top of the e and drop of water at a 45-degree angle and lower. Draw what the e looks like in box Place the slide on the stage and view in the lowest power 4x. Draw what the e looks like now in box 2. a. Review: how to view slides on a microscope: i. Use coarse adjustment knob to lower the stage. ii. Place slide on stage so the specimen is over the center and clip slide in. iii. Turn on light and rotate objective to 4x power. iv. Look through ocular lens and use course adjustment knob to raise the stage until the specimen comes into clear view STOP; do not use the coarse adjustment knob again. v. Use the fine adjustment know to focus the image. 5. Move the slide on the stage to the left, what happens? Move the slide to the right, what happens? 6. Re-center the slide and change the objective lens to the 10x power. Remember you do not need to move the stage at all. Just rotate the objective lens and use the fine adjustment knob to refocus the image. Draw what the e looks like now in box 3. Box 1 Box 2: 40x Box 3: 100x

3 Part II. Observing prepared bacterial slides 1. Place prepared bacterial slides on microscope and view at the highest magnification. Draw what you see at the highest magnification below. Note the magnification below. Bacterial Cells at magnification Part III. Observing Cheek Cells (Animal Cells) 1. Place a small drop of Iodine on a clean slide. 2. Using a toothpick, gently scrape the inside of your cheek. 3. Place the toothpick tip into the iodine and mix. The iodine stains the cells so you can see them. Place a coverslip on top of the slide. 4. Place the slide under low power. Draw what you see below. 5. Switch to higher power. Draw a few cells and include details of structures inside the cells in your drawing. Cheek Cells 40x Cheek Cells Part IV. Observing Leaf Cells (Plant Cells) 1. Place a drop of water on a clean slide. 2. Place an Elodea leaf in the drop of water and place a coverslip on top. 3. Place the slide under low power. Draw what you see below. 4. Switch to a higher power. Draw a few cells and include details of the structures inside the cells in your drawing.

4 Leaf Cells 40x Leaf Cells Part V. Observing pond or fish tank water organisms 1. Using a dropper, place a small sample of pond or fish tank water in a deep well microscope slide. 2. Place the slide under low power. Scan carefully for any moving organisms. When you find one, draw what you see below. 3. Switch to a higher power and scan carefully to look for any moving organisms under a higher magnification. Draw what you see below and record any observations about the organisms activity. Water Sample 40x Water Sample Observations:

5 Laboratory Questions: On a sheet of paper or in your laboratory notebook, answer the following questions. 1. What major differences did you see between the prokaryotic cell samples in part II and the eukaryotic cell samples in parts III and IV? 2. Compare and contrast your eukaryotic cell samples in parts III and IV. Were you able to identify the nucleus in both the animal and plant cells? What were the major differences you observed between plant and animal cells? 3. Your prokaryotic cell samples were dead, but the samples in parts II-V were living cells. Did you notice anything happening in these cells? 4. What types of organisms did you see in your water sample? Would you classify these organisms as prokaryotic or eukaryotic? Conclusion: On a sheet of paper or in your laboratory notebook, write one or two paragraphs that summarize your cell investigation and cover the following key points. 5. What are the major differences between prokaryotic and eukaryotic cells? 6. What are two major types of eukaryotic cells you observed? How are they alike and how are they different?