You Carry Eukaryotic Cells
Ch. 7 Cells
Name:
State Standard:
H.1L.4 -- Explain how cellular processes and cellular
differentiation are regulated both internally and externally in response to the
environments in which they exist.
Response
Scoring Rubric 1-4
10
Excellent
Responses are clear, complete and demonstrate a thorough
understanding of the subject matter
8
Proficient
Completes the assignment or experiment satisfactorily, but the
explanations have minor flaws
6
Adequate
Begins the assignment and explanation satisfactorily; but omits
significant parts or fails to complete.
4
Incorrect
Assignment and its explanations are not accurate. Group did
not demonstrate understanding or authentic knowledge
1
Fails to complete
Did not participate
Score
Introduction: Eukaryotic cells have a nucleus and other membrane-bound organelles. All
living organisms are made up of one or more cells. The cell is the basic unit of life and all
cells come from pre-existing cells. In this lab, you will be looking at two types of cells from
multi-cellular organisms. Using a microscope, you will examine epidermal cells from an onion
bulb and a human cheek cell. You will be looking for common structures found in eukaryotic
plant and animal cells.
Inquiry: What is the basic structure of plant and animal cells?
Pre-lab questions:
1. What cell structures should we see?
2. How are plant and animal cells similar in terms of organelles and
appearances?
3. How are they different?
Part A
Onion with Lugol’s Iodine
1. Obtain a piece of onion and peel off the thin layer of membrane on the inside surface.
2. Place it on a microscope slide and smooth out any wrinkles.
3. Place one drop of Lugol’s Iodine onto the membrane and cover
with a
cover slip.
4. Examine the onion cells using medium and high power.
5. Make a color diagram under each of the magnifications. Label
the
cell wall, cytoplasm, nucleus, and nuclear envelope.
Part B
Human Cheek Cells with Methylene Blue
1. Gently scrape the inside of your cheek with a toothpick to obtain a sample of
cheek cells and place it on a microscope slide.
2. Place on drop of Methylene Blue onto the cells and cover with a cover slip.
Use a small amount of paper towel to absorb excess stain!
3. Examine the cheek cells using medium and high power.
4. Make a color diagram under each of the two magnifications. Label the cell membrane,
cytoplasm, nucleus, and nuclear envelope.
Data
Onion cells
Medium Magnification_______X
Onion cells
High Magnification_______X
Cheek cells
Medium Magnification_______X
Cheek cells
High Magnification_______X
Analyses and Conclusions
1. Describe the shape of the onion cells and cheek cells. Are they regular or irregular in
shape? Identify factors that might determine cell shape and size.
2. Deduce why it was necessary to stain the onion cells and the cheek cells.
3. Cork cells come from the bark of the cork oak tree. Unlike onions, cork cells appear
empty when viewed under a microscope. Explain why the cork cells appear this way.