Download types of cells and their size

TYPES OF CELLS & THEIR SIZE
Name: _________________________
Background
The Earth currently contains somewhere between 10 and 30 million different species.
As you may remember, this diversity of life is categorized into five kingdoms (the
monera, protista, fungi, plants, and animals). Many of the differences between the 5
kingdoms of organisms are due to the fact that their cells are different in basic structure
and size. In the following activity, you will observe and learn to estimate the size of a
few of these cell types and determine the cellular differences that allow us to segregate
organisms into the five kingdoms.
Objective
1. You should know the functional parts of a microscope, how to determine the
magnification, how to focus a microscope, and estimate the size of cells under low,
medium, and high power. You should also be familiar with the major cellular
characteristics that allow people to distinguish between plant and animals cells, as
well as prokaryotic and eukaryotic cells.
Materials
microscope
onion and cheek cells
iodine and methylene blue
slides and cover slips
Procedure
Onion Cell Preparation
1. After setting up a microscope, use a scalpel blade to slice into the skin of the onion.
Then, using the tip of the same blade or tweezers carefully remove as thin a sheet of
onion as you can. It doesn’t need to be that big (you are looking at it under the
microscope).
2. Place the thin sheet that you have removed from the onion on a clean slide. Then,
apply a drop of brown-yellow iodine solution on top of the piece of onion. Be careful
NOT to get the iodine on others or yourself. Iodine is a dye that will stain your skin
and clothes.
3. Find the onion cells under low power, then view under medium or high power, make a
sketch, label the plant cell parts that you can actually observe, and estimate and
record the size of a single cell in the space provided in question 3. Then, wash the
onion off the slide and continue to the next step.
Cheek Cell Preparation
1. Use the flat end of a toothpick to scrape the inside of your cheek two or three times.
Transfer the slime to a cleaned slide, and spread it out in the middle of the slide.
2. Then, apply a drop of methylene blue solution on top of the slime on the slide. Use
your toothpick to stir the dye throughout the slime. Be careful NOT to get the
methylene solution on others or yourself. Methylene is a dye that will stain your skin
and clothes. Throw the toothpick away and acquire and place a cover slip over the
dyed cheek cells and return to your station for viewing.
3. Find the cheek cells under low power, then view under medium or high power, make
a sketch, label the animal cell parts that you can actually observe, and estimate and
record the size of a single cell in the space provided in question 3.
Amoeba Cell Preparation
1. If time permits prepare an amoeba slide. Use a dropper to suck up a small quantity
of water from the container where the amoebas are located. Place a cover slip on
the slide, find an amoeba under low power (they look like granular blobs with small
tentacle-like extensions – if you observe carefully they will actually move), view
under medium or high power, and make a sketch below.
Amoeba Cell
Pre-Lab Questions
1. Listen as your teacher explains how to prepare a specimen and how to focus the
microscope. During his explanation you should use the following terms to correctly
label the parts of the microscope (arm, base, coarse adjustment, diaphragm,
eyepiece, fine tune adjustment, light source, objective lenses, stage, stage clips)
Eye Piece
Objective
Total
Field of View
Magnification Magnification Magnification
Diameter
Low Power
10
4
10 x 4 = 40
4000 m
Medium Power
10
10
10 x 10 = 100
1600 m
High Power
10
40
10 x 40 = 400
400 m
2. Given the table above, what happens to the field of view as you move the objective
from its lowest power to its highest power?
3. Draw the cheek cells and onion cells to scale under medium or high power. Label the
cell parts that you can actually observe in each cell. Given the diameter of the
power you are observing under in the previous table, estimate size of both cells.
Onion Cells
Size = _______m
Cheek Cells
Size = _______m
4. Describe how you used knowledge of the diameter of field of view to aid you in your
estimate of the size of the cells you are viewing.
5. From recent class discussion, remind me of the function of the cell.
6. Then, list at least five things that a cell needs to carry out its function, and briefly
describe some fact about each.
o
o
o
o
o
7. Imagine that you had observed some bacteria cells in class today. After reading
about the two major classes of cells on page 114, describe how bacteria cells would
be different from the plant and animal cell we observed.
8. It is believed that the prokaryotic bacteria evolved into the eukaryotic protists, fungi,
plants, and animals. One major difference between the two groups is the
development of the nucleus and membrane bound organelles (endoplasmic
reticulum, golgi apparatus, and vesicles). Read about the origins of eukaryotes on
page 395, and describe in words and a sketch how a prokaryote may have changed
into a eukaryote.
9. Read the article “Organelles as Organisms” and describe what it suggests about the
origin of plant like and animal like cells containing chloroplasts and mitochondria.
Define the term endosymbiosis, and list distinct evidence that support the theory of
endosymbiosis.