MICC 211 Practical Report 1 PDF

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Introduction A light microscope (LM) is an instrument that uses visible light and magnifying lenses to examine small objects not visible to the naked eye, or in finer detail than the naked eye allows (Savile.B,Bracegirdle.B, 1998). Magnification, however, is not the most important issue in microscopy. Mere magnification without added detail is scientifically useless, just as endlessly enlarging a small photograph may not reveal any more detail, but only larger blurs. The usefulness of any microscope is that it produces better resolution than the eye. Resolution is the ability to distinguish two objects as separate entities, rather than seeing them blurred together as a single smudge.(Levine,S.Johnstone L,.1996) The history of microscopy has revolved largely around technological advances that have produced better resolution. Light microscopes date at least to 1595, when Zacharias Jansen (1580–1638) of Holland invented a compound light microscope, one that used two lenses, with the second lens further magnifying the image produced by the first (Werner.N.,1997). His microscopes were collapsing tubes used like a telescope in reverse, and produced magnifications up to nine times (9x). Antony van Leeuwenhoek (1632–1723) invented a simple (one-lens) microscope around 1670 that magnified up to 200x and achieved twice the resolution of the best compound microscopes of his day, mainly because he crafted better lenses. While others were making lenses by such methods as squashing molten glass between pieces of wood, Leeuwenhoek made them by carefully grinding and polishing solid glass. He thus became the first to see individual cells, including bacteria, protozoans, muscle cells, and sperm. Englishman Robert Hooke (1635- 1703) further refined the compound microscope, adding such features as a stage to hold the specimen, an illuminator, and coarse and fine focus controls. Until 1800, compound microscopes designed by Hooke and others were limited to magnifications of 30x to 50x, and their images exhibited blurry edges (spherical aberration) and rainbowlike distortions (chromatic aberration). According to (Rogers, K,. 1999) The most significant improvement in microscope optics was achieved in the nineteenth century, when business partners Carl Zeiss (1816–1888) and Ernst Abbe (1840–1905) added the substage condenser and developed superior lenses that greatly reduced chromatic and spherical aberration, while permitting vastly improved resolution and higher magnification.

Aim: To become familiar with the light microscope, its part and its functions.

Material and methods Wet mount of hay infusion The hay infusion was mixed very well. Using the dropper that was provided, the small amount of hay infusion was removed. On the microscope slide, two drops of hay infusion were placed. The slide was covered with cover slip with extremely great care to avoid air bubbles being created. The wet mount preparation was examined under the light microscope using 40x objective. Simple staining hay infusion The hay infusion was mixed well. Two drops of hay infusion were removed and placed in a microscope slide using the dropper. The microscope slide with hay infusion was passed over the flame frequently until it became dry. The methylene blue was applied gently and carefully over the dry areas with the hay infusion and was allowed to rest for a period of 1 minute. After a minute the methylene blue was removed with water. The slide was examined under the light microscope. Discussion When the hay infusion was examined under the light microscope, the chain of Bacilli was observed using 40x up to 100x objective. From the hay infusion it was expected to find any kind of bacterial, fungal and or viral species because the infusion is extracted from the plant through some sort of fermentation process. The results that were obtained during the wet mount hay infusion method were the same as the results that were obtained during simple staining of hay infusion method. The only difference between these two methods is that they are carried in different ways but the results they give are the same when carefully examined under the light microscope. Conclusion With the chain of bacilli bacteria which are microscopic organisms being able to be examined and identified under the light microscope, it is concluded that the light microscope is effective enough to be used in trying to examine microorganisms in laboratories. Although this light microscope is effective, there are some certain modifications that need to be added because the light microscope makes it difficult to quickly identify the microorganisms.

References 1. Bradbury, Savile, and Brian Bracegirdle. Introduction to Light Microscopy. New York: Springer-Verlag, 1998. 2. Jones, Thomas E. History of the Light Microscope. 3. Nachtigall, Werner. Exploring with the Microscope: A Book of Discovery and Learning. London: Sterling Publications, 1997. 4. Rogers, K. The Usborne Complete Book of the Microscope. Tulsa, OK: EDC Publishing, 1999. 5. Levine, S., and Johnstone L,.. The Microscope Book. New York: Sterling Publishing Co., 1996.

UNIVERSITY OF FORT HARE

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NAME

: CUBEKA AYAKHA

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STUDENT NUMBER

: 201402569

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TITLE OF EXPERIMENT: LIGHT MICROSCOPY

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GROUP NUMBER

: 05

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COURSE CODE

: MIC 211

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DATE OF PRACTICAL : 29 FEBRUARY 2016...