Yusuf İslam ŞEFLEK
30.09.2011
OBSERVING ANIMAL AND PLANT CELLS UNDER THE LIGHT MICROSCOPE
Aim:
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In this experiment, structural properties and some organelles of plant and animal cells
as eukaryotic cells will be observed.
Question:
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Are the animal cells and plant cells are visible in the light microscope?
Introduction:
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Cells are basic units of all living organisms. Cells come from pre-existing cells. Cells
consist of cytoplasm, enclosed in a plasma membrane, usually controlled by a single
nucleus. We can classify cells as prokaryotic and eukaryotic cells.
Eukaryotic cells are more complicated and bigger in size, than prokaryotic cells.
Some eukaryotic cells have cell wall made up from citin, cellulose and etc. They have
plasma membrane that surrounds the cytoplasm, give the cell its shape and controls
entry and exit of the substances. Eukaryotic cells have cytoplasm, nucleus,
mitochondria, lysosome, endoplasmic reticulum, ribosome, golgi apparatus, vacuole
and plant cells have also chloroplast and a bigger vacuole.
Hypothesis:
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As animal cells and plant cells have cell membranes and nuclei they can be observed
and examined under the light microscope. The taken cells should be carefully placed
on the glass for observing. The light intensity should be managed properly in case of
not seeing the cells clearly. Also magnification ratio should be settled up carefully. If
all the variables are kept valid the experiment would reach the success.
Apparatus:
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Light Microscope
Slide
Cover Slip
Paper Towel
Water
Methyl Blue
Moss Leaf Cell
Human Cheek Cell
Dropper
Beaker
Toothpick
Scissors
Yusuf İslam ŞEFLEK
30.09.2011
Procedure:
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Firstly beaker is filled with water.
By using dropper, water is taken from beaker and dropped on slide(one drop of water).
Toothpick is touched inside of the cheek and some human cheek cells are taken.
Toothpick is touched to the drop of water on the slide and by this way human cheek
cells are transferred to the water.
Then one drop of methyl blue is added to the one drop of water and human cheek cells
on the slide.
Cover slip is put on the drops by 45 degree.
Excess liquid coming out of cover slip is cleaned by using papertowels.
Slide is put on the stage part of under light microscope and by using light source,
diaphragm, coarse adjustment knob and fine adjustment knob, it is tried to catch the
best vision by looking at ocular lens at the same time.
Cells are observed by using magnifications of 20x, 50x and 200x.
For each observation, scientific drawings are made.
Then again by using burette, water is taken from beaker and dropped on slide(one drop
of water) for the plant cell to be observed.
By using scissors, a thin part of leaf is taken onto the drop of water on the slide.
After that one drop of methyl blue is added on the thin leaf sample.
Cover slip is put on the drops by 45 degree.
Excess liquid coming out of cover slip is cleaned by using papertowels.
Slide is put on the stage part of under light microscope and by using light source,
diaphragm, coarse adjustment knob and fine adjustment knob, it is tried to catch the
best vision by looking at ocular lens at the same time.
Cells are observed by using magnifications of 20x, 50x and 200x.
For each observation, scientific drawings are made.
After the experiment, apparatus are cleaned.
Observations:
Under the light microscope, the cells of human cheek cells were observed as points at
magnification 20x. They were a little bigger at magnification 50x and seen like circular
shapes. At magnification 200x, they were seen like circles having little points inside them.
For the leaf sample, at 20x magnification a rectangular shape was observed having a
thin tube-like structure inside it and some little points around that tube-like structure. At
magnification 50x, little points were seen as rectangular shapes arranged in and regular order
that they touch each other. At magnification 200x, again some rectangular shapes were seen
having dark colored points and some green circles inside them.
Evaluation and Conclusion:
It is observed that the circular shapes are animal cells and little points inside them are
nuclei. Cell membrane is also seen.
Yusuf İslam ŞEFLEK
30.09.2011
For the leaf cell, it is observed that rectangular shapes are plant cells and little points
are nuclei. Green circles represents chloroplasts and it has also a cell membrane. Since the
part that surrounds cytoplasm and nucleus is seen darker in plant cell, it can be understood
that it has also a cell wall.