1.1 Setting up and using the microscope
Introduction
There are
certain living organisms that are too small to be seen with our naked eye, such
as microorganisms. So, the microscope is used to create an enlarged view or
magnified visual of the microorganisms. There are two common types of
microscope, light microscope and electron microscope. The light microscope is
an instrument use visible light and magnifying lenses to view the
microorganisms. It will provide visible details of the specimen to human eyes.
It produces a better resolution than eyes, means that it able to distinguish
two very small and close spaced objects as separate entities.
The eyepiece
tube receives the light that passes through the objective lens then redirects
it to the eyepiece lens. The eyepiece lens have the magnification power of
10x.The objective lens of microscope provide four magnifications power, which
are 4x, 10x, 40x and 100x. In order to
produce a magnified primary image, the objective lens focuses the light beam
which passed through the specimen.
The stage of microscope is a place to put the slide of
specimen. On the stage, there is a pair of stage clips that used to keep the
slide in place. The diaphragm is used to adjust the total light that will enter
the condenser; it has different
size of holes and is used to control the intensity of light that will be
directed onto the slide. The light source of microscope is come from the light
source bulb which located at the base of microscope.
The coarse adjustment knob and fine adjustment knob are important in the
focusing of the image of specimen. When these knobs are adjusted, the stage
will be raise or lower. The sequence of using the knobs is coarse adjustment
knob followed by the fine adjustment knob. The purpose of the condenser
lens is to focus the light onto the specimen.
Resolving power of
microscope is the ability to distinguish two very close distance and small
objects as the different entities. Magnification is an apparent
enlargement in size of an object so the object can be seen clearer and more
details can be seen. By multiplying the objective lens' power and the eyepiece
lens' power, the total magnification of the image of the specimen can be seen.
There are four magnifications given by
microscope:
4x objective X
10x eyepiece = 40x magnification
10x objective X 10x eyepiece = 100x magnification
40x objective X
10x eyepiece =400x magnification
100x objective X 10x eyepiece =1000x magnification
Objectives
To learn
the correct and accurate way to use a bright-field microscope
To improve
the knowledge regarding the magnification and resolution of the microscope
To provide
more experience in the use of microscope
Materials
and Reagents
Cover-slip, immersion oil, marker pen
and microscope slide
Procedure
(Refer to lab manual)
Results
Bacteria types: Cocci, Bacilli, Spirilli
40 x magnifications
100 x magnifications
400 x magnifications
1000 x magnifications (oil immersion)
Discussion
There are three basic shapes of bacteria: coccus,
bacillus, and spiral. Cocci may
be spherical, oval,
elongated, or flattened. They can exist in single coccus, pairs
(diplococci), in chains (streptococci), in group of four (tetrad), in cube (sarcinae) and in clusters (staphylococci). Cocci do not dry
out quickly and retain water, but they absorb nutrients slowly. Bacillus is rod-shaped and has four types: single bacillus,
diplobacilli, strepobacilli, and coccobacillus. Bacillus has a
large surface area that able to absorb nutrients, but they might dry out easily. Example for bacillus bacteria is Escherichia
coli. Spiral bacteria have twists in three types: Vibrios (curved), Spirilla (helical) and Spirochetes (thin). Spirilla have
flagella at both ends that allow them to move like a corkscrew, and capable to
move faster than other bacteria. Their rigid cell wall helps to maintain their
shape.
Conclusion
The
experiment 1.1had showed the accurate way of using light microscope. We learn
the components of microscope and their functions. Through this experiment, we
learn the correct procedure to use the microscope to obtain a clear image of cells
and microorganisms.
References
http://classes.midlandstech.edu/carterp/courses/bio225/chap04/lecture2.htm
1.2
Examination of cells
Introduction
Oil immersion technique is used to
enhance the resolving power of microscope. The bacteria observed with the oil
immersion objective are finer in resolution and have a brighter image. Wet
mount method is used due to its quick preparation, simple steps and possible to
observe moving and living organisms.
Objectives
To learn how to make the wet mount slide
To obtain more experiences in using the microscope
Materials
and reagents
Culture, immersion
oil, lens tissue, a microscope slide containing stained microorganisms,
inoculating loop, Bunsen burner, slide and cover slip
Lactobacillus
fermentum
Procedure
(Refer to lab manual)
Results
Bacteria type: Lactobacillus
fermentum
Shape: Rod
Size: Tiny
Colour: Transparent white
1000 x magnifications (oil immersion)
Discussion
Lactobacillus sp is a rod-shaped,
gram-positive and non-spore-forming bacterium belongs
to family Lactobacillaceae. Lactobacillus sp has the ability to
produce lactic acid as a by-product of glucose metabolism. Lactobacillus sp is normally non motile and can survive in both aerobic and
anaerobic environments. Although they require rich media to grow, they are
ubiquitous and may survive in anywhere contains carbohydrates, including respiratory, gastrointestinal, and urogenital tract of human and animals. In daily life, Lactobacillus sp is useful in the production of cheese
and yogurt; in manufacturing of pickles and beverages like wine
and juices. In medicine field, Lactobacillus sp is used for treating diarrhea and digestion problems such as irritable bowel syndrome (IBS) and colic in babies.
Conclusion
In the
experiment 1.2, we observe the behaviour of Lactobacillus sp by using the oil immersion objective
lens which is in high power. Besides, wet mount method is used to see the
nature state of the bacteria. The technique of using microscope in experiment
1.1 helps us to use the microscope correctly to obtain a clear image of Lactobacillus sp.
References
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