LAB 1: PRINCIPLES AND USE OF MICROSCOPE
INTRODUCTION
A microorganism (from the Greek: μικρός, mikrós, "small" and ὀργανισμός, organismós, "organism"; also spelt micro-organism, micro organism ormicroörganism) or microbe is a microscopic organism that comprises either a single cell (unicellular) or cell clusters. Micoorganisms is invisibles to our naked eyes. The first study about microorganisms(microbiology) is by Anton van Leeuwenhoek in 1675 by using his own invention of microscope. Microorganisms is devided into few groups, there are bacteria, fungi, protists and others. We can observe the morphology of the micoorganisms by using microscope.
Microscope.
Parts of Optical microscope
A microscope is a instrument that has been used in microorganisms study. It used to examine organisms and structures invisibles to our naked eyes. There were two categories of microscope which is light(optical) and electron microscopy. The compound microscope uses lenses and light to enlarge and view the microbes observed. The light micoscope obtain the magnification through a system of optical lenses whereas the electron microscope a bean of electrons is used to produce the enlarged image. Alternatively microscopes can be classed on whether they analyse the sample via a scanning point (confocal optical microscopes, scanning electron microscopes and scanning probe microscopes) or analyze the sample all at once (wide field optical microscope and transmission electron microscopes).
The light microscopy can be divided into six-sub categories which is bright field, dark field, ultraviolet fluorescence, phase contrast and differential interference contrast(D.I.C). The compound microscope has two systems of lenses for greater magnification,
1) the ocular, or eyepiece lens that one looks into and
2) the objective lens, or the lens closest to the object.
Before purchasing or using a microscope, it is important to know the functions of each part. The parts of microscope are
Eyepiece Lens: the lens at the top that you look through. They are usually 10X or 15X power.
Tube: Connects the eyepiece to the objective lenses
Arm: Supports the tube and connects it to the base
Base: The bottom of the microscope, used for support
Illuminator: A steady light source (110 volts) used in place of a mirror. If your microscope has a mirror, it is used to reflect light from an external light source up through the bottom of the stage.
Stage: The flat platform where you place your slides.
Revolving Nosepiece or Turret: This is the part that holds two or more objective lenses and can be rotated to easily change power.
Objective Lenses: They almost always consist of 4X, 10X, 40X and 100X powers. When coupled with a 10X (most common) eyepiece lens, we get total magnifications of 40X (4X times 10X), 100X , 400X and 1000X
Rack Stop: This is an adjustment that determines how close the objective lens can get to the slide.
Condenser Lens: focus the light onto the specimen. Condenser lenses are most useful at the highest powers (400X and above
Diaphragm or Iris: rotating disk under the stage and is used to vary the intensity and size of the cone of light that is projected upward into the slide.
The proper way to focus a microscope is to start with the lowest power objective lens first and while looking from the side, crank the lens down as close to the specimen as possible without touching it. Now, look through the eyepiece lens and focus upward only until the image is sharp. If you can't get it in focus, repeat the process again. Once the image is sharp with the low power lens, you should be able to simply click in the next power lens and do minor adjustments with the focus knob. If your microscope has a fine focus adjustment, turning it a bit should be all that's necessary. Continue with subsequent objective lenses and fine focus each time.
RESULT
1) STAINED CELLS
Streptococcus sp.
40x magnification
100x magnification
400x magnification
2) WET MOUNT
Lactobacillus fermentum sp. 1000X magnification
Saccharomyses cerivisae sp. 1000x magnification
DISCUSSION
In biology morphology is the studied about of the form and structure of the microorganisms and the specific features of them. This includes aspects of the outward appearance (shape, structure, colour, pattern) as well as the form and structure. Bacteria displays a wide of morphology in shapes and their sizes and this is called morphology. The general morphology of the true bacteria are spherical or coccus type, rod shape or bacillus type or spiral shaped. Coccus bacteria are spherical or ellipsoidal and such cells are called "cocci." Bacillus type bacteria are elongated and either cylindrical or straight rod-like and such cells are called bacilli. Spirillum type bacteria are spirally coiled or long corkscrew-shaped, spiral cells known as spirilla. Different types of bacteria will produce colonies that are distinctive in appearance such as colours, shapes and sizes. This is called colony morphology. There are a few basic characteristics of colony morphology that are typically evaluated.
- Form - the basic shape of the colony. For example, circular, filamentous, etc.
- Elevation - the cross sectional shape of the colony. Turn the Petri dish on end.
- Margin - the magnified shape of the edge of the colony.
- Surface - the surface of the colony appear. For example, smooth, glistening, rough, dull (opposite of glistening), rugose (wrinkled), etc.
- Opacity - transparent (clear), opaque, translucent (almost clear, but distorted vision, like looking through frosted glass), iridescent (changing colors in reflected light), etc.
- Chromogenesis (pigmentation) :white, buff, red, purple, etc.
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CONCLUSION
Microscope can be used in observing the morphology of the microorganisms in a wide range.We can used different magnification(40x, 100x, 400x, 1000x) to observe the microorganisms. 1000x is used for oil immersion specimen. In this experiment, the basic principles in using and handling of the microscope can be obtained and the morphology of the specimen can be observed.
REFERENCES:
http://www.sciencebuddies.org/science-fair-projects/project_ideas/MicroBio_Interpreting_Plates.shtml
http://en.wikipedia.org/wiki/Gram_staining
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