Download Investigating Cells and Cellular Organelles

Name: _____________________________
Period: _____ Date: _________________
CELL TYPES
Prokaryote
Define:
Eukaryote
Define:
Distinguishing
characteristics:
PLANT
Distinguishing
characteristics:
Examples:
ANIMAL
Distinguishing
characteristics:
Examples:
Virus
Examples:
Investigating Cells and Cellular Organelles
References: pages 168-181 in textbook.
Purpose:
In this lab you will prepare “wet mounts,” describe, sketch, and label cells and cellular organelles; employ
staining techniques; and become familiar with similarities and differences between plant, animal, protest,
moneran, and virus cell types.
Pre-lab Questions:
1. Although cells vary greatly in form and function, all cells have certain structures in common. A
basic knowledge of the structure of a cell is essential to an understanding of the cell as the unit of
___________________ and ____________________ of living things.
2. List the three major assumptions of the Cell Theory (p.170)
1. ________________________________________________________________
2. ________________________________________________________________
3. ________________________________________________________________
Procedures:
Prokaryotic Cells: Bacteria (Lactobacillus, sp.)
You will make a wet-mount of Lactobacillus, a bacterium adapted to live on lactose (milk sugar).
Lactobacillus converts milk to yogurt and is used in many parts of the world by people deficient in the
enzyme lactase, as the yogurt is easier to digest than milk.
 Place a dab of yogurt/water mixture on a microscope slide.
 Add a cover slip and examine under low power. Rotate the lens to High Power and focus on the rodshaped cells.
 Sketch the entire field of vision in Figure 1, reflecting the number of bacteria cells. Avoid “clumps” of
milk solid on the slide.
 In the box, sketch one of the bacterial cells enlarged. See teacher for example of one.
 LABEL: Cell Wall, Cytoplasm
1. How do Prokaryotic cells differ from Eukaryotic cells? (pp.172-173)
_____________________________________
_____________________________________
2. Name the important structure missing in Prokaryotes:
__________________________
3. Do Prokaryotes still have DNA? ________ Where
is it Located? ___________________
4. Name two other foods (besides yogurt)
Prokaryotes help manufacture:
__________________________ and
_____________________________
5. Prokaryotes can cause human diseases. Name 2 of
them:
___________________________ and
_______________________________
Figure 1
ELODEA: “Water Weed” (Elodea canadensis) Common aquarium plant
 Mount one green leaf from the Elodea plant on a slide and add one drop of water. Add a cover
slip and observe under Low Power first, then High Power.
 Sketch one cell under High Power in Figure 2.
Figure 2
 LABEL: Cell wall, Cell Membrane, Cytoplasm, Nucleus,
Chloroplast
1. The green organelles in the cytoplasm are called:
___________________________
2. What important molecules are found in these
“green” organelles? ___________________
3. What biochemical process are these organelles
responsible for? _______________
4. The outer boundary of a plant cell is the ___________
________________ and is made up
of ____________________________ fibers.
5. Carefully look at the chloroplasts in the Elodea Cells. Are they moving? ________
How are they moving? (p181) ____________________________________________
Onion Cell: Fresh Onion Bulb
 Carefully peel a section of the skin from the inside layer (concave) of the onion and place it on the
slide.
 Add one drop of water and one drop of Iodine stain,
then lower the cover slip.
 Focus on Low Power first, then bring it up to high power. Sketch
ONE onion cell enlarged in Figure 3.
 LABEL: Cell wall, Cell Membrane, Nucleus, Cytoplasm,
Vacuole, Nucleolus.
1. Compare the onion and Elodea
“organelle” is missing from the
__________________
cells. What
onion cell?
2. WHY is the organelle missing from the onion? Be
specific… _________________________________
Figure 3
Potato Cells:
 Get a small cube of fresh potato. Using a sharp razor blade, shave a VERY thin piece off the end
of the cube.
 Place the slice on the slide and add one drop of Iodine. Wash off excess Iodine, place a cover
slip on and observe under Low Power. Sketch what you see in Figure 4. You should sketch more
than one cell- there should be a few side by side.
 LABEL: Cell Wall, Starch Grains
1. Explain how potato and Onion Cells are similar: ___________________________
_______________________________
2. What color change results from the Iodine stain?
____________ to ____________
3. What part of the potato is affected by the Iodine?
___________________________
4. Potato starch is a mono-, di-, or poly-saccharide?
___________________________
How do you know?
___________________________________
5. What is the major function of starch in a potato?
___________________________
Figure 4
EPITHELIAL CELLS: Human Cheek Cells (Homo sapiens)
 Place a drop of Methyl Blue and one drop of water in
the middle of a slide.
 Gently scrape the inside of your cheek with a clean toothpick and stir into the liquid on your slide. Add
a cover slip carefully.
 Observe the cell(s) under Low Power, then sketch one epithelial cell in Figure 5. Switch to Medium or
high power if necessary.
 LABEL: Cell Membrane, Cytoplasm, nucleus, nucleolus.
1. Compare the cheek cells to the three plant cells. What two organelles are NOT found in
cheek cells and other animals cells?
__________________ and __________________
2. The outer boundary of an animal cell is called the
____________________________
It is made of 2 lipid layers, plus
____________________ & _____________________
3. Do plant cells have the structure in number 2?
________________________________
Figure 5
BLOOD CELLS: Prepared Slide of Human Blood Smear (Homo sapiens)
 Focus on Low Power then observe under High Power. Sketch several cells in
Figure 6.
 LABEL: White Blood Cells, Blood Platelets, and Red Blood Cells. See teacher if you need help.
**Read pages 952-953 for help with these questions.
1. What’s another name for red blood cells?
___________________________________
2.What protein is found in red blood cells?
________________________________
3. What does this protein do for our cells?
_________________________________
4. What important organelle is missing from mature red
blood cells? ____________________________
Figure 6
5. Without this organelle, what important function can
they not carry out? ________________________
6. What is another name for white blood cells? ________________________________
7. What is the function of white blood cells? ____________________________________
8. Based on your observations, what is the approximate ratio of red to white blood cells? _____________
9. When would you expect to have fewer white blood cells in
your body? _______________________________________________
10. Where are new blood cells made? _________________________________________
Virus
 Sketch the picture of a virus, provided by your instructor, in Figure 7.
 Label: Protein Coat, DNA/RNA, Tail
1. How is the virus cell different than all other cells observed in this lab? _____________
______________________________________________________________________
**Refer to pages 478; 482-483 for #2 & 3
2. What is unique about the genetic material (nucleic acids) of some
viruses? __________
___________________________________
3. Do you consider viruses “Life?” Why or why not?
_____________________________
_________________________________
Figure 7
Discussion Questions:
1. Name the simplest cell type (other than virus) that was observed in this lab:
__________________. What does this cell type have or lack that makes it the simplest?
___________________.
2. Name three structures or organelles that are found in plant cells but NOT in animal cells:
1. ____________________________________
2. ____________________________________
3. ____________________________________
3. Stains are often used when working with cells.
 List one advantage of using stains: ___________________________________
 List one disadvantage of using stains: ________________________________
Conclusion:
In a paragraph below answer the following: 1) Summarize the differences between plant and
animal cells. 2) Compare and contrast eukaryotes and prokaryotes. 3) Include the 2 structures
ALL cells have in common.
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