1. Introduction
"Micro" refers to tiny, "scope" refers to view or look at. Microscopes are tools used to enlarge images of small objects so as they can be studied. Microscopes range from a simple magnifying glass to the expensive electron microscope. The compound light microscope is the most common instrument used. It is an instrument containing two lenses, which magnifies, and a variety of knobs to resolve (focus) the picture. It is a rather simple piece of equipment to understand and use.
2. Materials
A microscope
Glass slide
Cover slip
3. Method Used
Setting up a microscope
1. Sit on your stool with your knee under the bench and move the microscope so that you look through
both eyepieces without straining. Make sure you are comfortable.
2. After plugging in the power lead of the microscope and turning on the power, turn on the microscope
light using the main on-off switch.
3. Adjust the light intensity using the brightness control. Position 5 is normally adequate.
4. Rotate the revolving nosepiece to bring the 4x objective lens into the light path.
5. Take a clean slide and mark a line on it with a marker pen. Place the slide on the stage, using the
spring clip to secure it. Move the slide into the light path using the coaxial stage control knobs.
6. Look through both eyepieces and adjust them until you see a single circle of light. For future
reference, make a note in your class manual of the setting on the interpupillary distance scale.
7. Rotate the tube length adjustment (diopter) ring on the right eyepiece to match your interpupillary
distance setting obtained in 1.6.
8. Using the right eye only, focus the marker-pen mark by adjusting the coarse and fine adjustment
knobs.
9. Using the left eye only, focus the left eyepiece using the tube lens adjustment (diopter) ring. Again
for future, make a note in class manual of the diopter ring setting
1.2 Examination of Cells
1. Introduction
Some samples can be placed directly under the microscope. However, many samples look better when placed in a drop of water on the microscope slide. This is known as a "wet mount." The water helps support the sample and it fills the space between the cover slip and the slide allowing light to pass easily through the slide, the sample, and the cover slip.
2. Materials
Culture
Immersion oil
Lens tissue
A microscope slide containing stained microorganisms
Inoculating loop
Bunsen burner
Slide and coverslip
3. Procedure
Stained cells:
1. Set up microscope as described above and examine the slide under the oil immersion lens.
2. Observe the shape and size of the organisms and any structure that are visible. Draw what you see.
The wet mount:
1. Use a sterile Pasteur pipette to aseptically transfer one drop of culture to the centre of a glass slide.
2. Use a marker pen to mark a coverslip. This mark will help you to focus on the microorganisms.
3. Take the coverslip and turn it so that the marker pen mark faces down. Then place one edge of the
coverslip onto the slide and gently lower it so that it covers the drop of culture. The culture will
spread between the coverslip and the slide.
4. Place the slide on the microscope stage and using the 4x objective focus on the culture. You may see
two or three groups of highly motile protozoa.
5. Observe the cell using the 10x and the 40x objectives. By observing closely you may be able to
detect some smaller moving objects. They will be some of the larger types of bacteria. Make drawing
of what you see.
6. Observe the cells using oil immersion lens. Remember to adjust the condenser and diaphragm. Again
make drawings and comment on anything of interest you see.
7. Repeat this procedure with other cultures.
4. Results
Stained Cell under Microscope
1) Bacteria type: Cocci, Bacilli, Spirilli
(40x magnification)
100x magnification
400x magnification
Oil immersion, 1000x magnification
2) Typical Bacillus
40x magnification
100x magnification
400x magnification
Oil Immersion 1000x magnification
3) Penicillium Conidia
40x magnification
100x magnication
400x magnification
1000x magnification
Wet Mount:
Discussion:
The morphology of Lactobacillus fermentum :
-Shape: Rod
-Size: Tiny
-Surface: Smooth
-Texture: Moist
The morphology of Typical Bacillus
-Shape: Rod
-Size: Tiny
-Surface: Smooth
-Texture: Moist
The morphology of Penicillium Conidia
-Shape: highly branched network of multinucleate, septate, usually colorless hyphae
-Size: Medium
-Surface: Smooth
Conclusion:
As a conclusion, i have learned the right techniques to use a microscope. I also learned the right way to practice aseptic technique to avoid contamination to occur while handling cultures. I have obtained a clear view on the morphology of the microorganisms like Lactobacillus fermentum in this experiment by using immersion oil which could ensure magnification of 1000x achieved while still preserving good resolution.
Reference:
- http://en.wikipedia.org/wiki/Bacillus_(shape)
- http://en.wikipedia.org/wiki/Penicillium
- http://en.wikipedia.org/wiki/Microscope
- http://ibg102.wordpress.com/2013/04/05/lab-1-principles-and-use-of-microscope/
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