Chapter 3
Cell Structure and Function
Name
Date
Score
Lab: Prokaryotes vs. Eukaryotes
The vast diversity of living organisms can be grouped into two types of cells – Prokaryotes and
Eukaryotes. Prokaryotes are bacteria and archaea. All other living organisms like plants, animals, fungi and
protists are eukaryotes.
All cells share certain features like a plasma membrane, cytosol and DNA. However, there are many
differences between prokaryotes and eukaryotes. The primary identifiable difference between prokaryotes and
eukaryotes are a membrane bound nucleus and membrane enclosed organelles. Prokaryotic cells have no
nucleus or membrane bound organelles. Other differences include prokaryotes are single celled, most have a
cell wall, and less complex DNA. Eukaryotes have a nucleus which contains chromosomes, can be single or
multi-celled, and have more complex genomes.
Objective:
Observe, sketch and classify several cells as prokaryotes or Eukaryotes
Procedure Part 1:
1. Obtain a compound microscope and obtain one of the following slides: Cork, Liver,
Spirulina, or Stagnant water. You will look at all of the slides during the lab but just start
with one.
2. Observe the cell on low power first. Once the image is focused, switch to the medium
focus and adjust with the fine focus knob only. Observe features in the cell.
3. Finally use the highest power objective to observe the cells. Use only the fine focus knob.
4. Sketch the appearance of the cells in the data table and observe and record any specific
features of each cell.
Data Table and Observations:
Slide Name
Sketch
Observations
Prokaryote or
Eukaryote
Part 2:
Onion Cell Procedure:
1. Get a clean slide. Take a piece of onion from the bowl in the front of the room. Obtain one
layer of epidermal tissue (your teacher will demonstrate this in class). Place the layer of tissue
on a slide and then add a small drop of iodine to the slide. Place a cover-slip on the slide,
slowly lowering it over the sample to avoid creating air bubbles. Iodine is not toxic but does
stain!
2. View the slide under the low power. Once you have found an area with several good cells,
switch to high power. Remember to only use the fine adjustment to focus at higher powers.
3. Draw one or two onion cells in detail on the highest power on the attached page. Label the
following: cell membrane, cytoplasm, cell wall, vacuole, nuclear membrane, nucleus.
When drawing objects as seen under a microscope, it is important to:
a. draw clearly, make distinct lines, only use pencil, provide the name of the object and the
power under which it was observed
4. Clean the slide and dry and use slide and cover slip.
Cheek Cell Procedure:
1. Put a drop of methylene blue on a slide. Caution: methylene blue will stain clothes and skin.
2. Gently scrape the inside of your cheek with the flat side of a toothpick. Scrape lightly.
3. Stir the end of the toothpick into the stain and throw the toothpick away.
4. Place a cover-slip onto the slide
5. Use low power to focus. You probably will not see the cells at this power. Once you have found
an area with several good cells, switch to high power.
6. Neatly draw one or two cheek cells on the attached page.
membrane, nucleus, nuclear membrane, cytoplasm
Label the following:
7. Throw out the clean slide and use for part 3. Throw out cover slip!
cell
Part 3 Protists:
1. Using the microscope, examine the sample of pond water. Use the spaces below to sketch a
few of the organisms you observe. You may also use the protist keys to help identify some of
the organisms. When you are finished, rinse and clean your slide.
Discussion Questions:
1. Describe how the region that contains the genetic material is different in prokaryotic and
Eukaryotic cells.
2. Explain three general differences between prokaryotic and eukaryotic cells.
3. Describe how the shape of the onion cells are different than the cheek cells.
4. Which structures could be seen in both onion and cheek cells?
5. Both plant and animal cells contain mitochodrian yet none were visible. Why or why not?
Explain your thinking!
6. One difference between plant and animal cells is plant cells contain chloroplasts. Did the
onion cells contain any chloroplasts? Why or Why not? Explain your reasoning!
7. Can you identify any algae? How can you identify algae from other protists in the sample?
8. Can you identify any protozoans in the sample? If so label them in your drawings.