Lab 4271

1.1 Setting up and using the microscope

Introduction

A microscope (from the Greek: μικρός, mikrós, "small" and σκοπεῖν, skopeîn, "to look" or "see") is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy.
Microscopic means invisible to the eye unless aided by a microscope. Microscopes magnify microscopic specimens and make them appear larger than they truly are. This allows us to accurately study and describe cells and microscopic organisms.

The Part of The Microscope

· eyepiece-where you look through to see the image of your specimen.

· body tube-the long tube that holds the eyepiece and connects it to the objectives.

· nosepiece-the rotating part of the microscope at the bottom of the body tube; it holds the objectives.

· objective lenses-(low, medium, high, oil immersion) the microscope may have 2, 3 or more objectives attached to the nosepiece; they vary in length (the shortest is the lowest power or magnification; the longest is the highest power or magnification).

· arm-part of the microscope that you carry the microscope with.

· coarse adjustment knob-large, round knob on the side of the microscope used for focusing the specimen; it may move either the stage or the upper part of the microscope.

· fine adjustment knob-small, round knob on the side of the microscope used to fine-tune the focus of your specimen after using the coarse adjustment knob.

· stage-large, flat area under the objectives; it has a hole in it (see aperture) that allows light through; the specimen/slide is placed on the stage for viewing.

· stage clips-shiny, clips on top of the stage which hold the slide in place.

· aperture-the hole in the stage that allows light through for better viewing of the specimen.

· diaphraghm-controls the amount of light going through the aperture.

· light or mirror-source of light usually found near the base of the microscope; the light source makes the specimen easier to see.

Results

· Stained Cells

Streptococcus sp. - 40x

Streptococcus sp. - 1000x

Streptococcus sp.- 4000x

· Wet Mount

Saccharomyces arevisiae sp. (yeast) – 1000x

Lactobacillus fermentum sp. - 1000x

Discussion

Bacteria is too tiny to be discovered by low-power or high-power dry objectives. Instead they are stained and observed with the oil immersion objectives that being used only at very large magnifications that require high resolving power. Objectives with high power magnification have short focal lengths, facilitating the use of oil. The oil is applied to the specimen (conventional microscope), and the stage is raised, immersing the objective in oil.

Another method in used in the examination of unstained bacteria with the use of the microscope is the wet mount method. Wet mounts can detect the characteristics of most types of known bacteria. The method classifies bacteria by type as being gram positive, gram negative or gram variable. The classification of the bacteria in question is determined by the color that is seen under the microscope after the chemical stain has been added to the mount. The color that is exhibited by specific bacteria is directly related to the bacterial cell wall's ability to retain the color during examination.

Saccharomyces Cerevisiae (Yeast)

Saccharomyces cerevisiae, which in Latin means “sugar fungus,” has been utilized by humans for thousands of years. It is believed that it was first discovered on the skins of grapes. S. cerevisiae is a budding or brewing yeast, and has been put to use since antiquity to make dough rise and to provide ethanol in alcoholic beverages.

Its deeply detailed cellular structure makes S. cerevisiae, also known as "brewers yeast," one of the most highly researched model organisms in the study of biology. It exists in single-cell form, or in pseudomyceliac form. Cellular reproduction occurs by budding. The ability of S. cerevisiae to ferment specific sugars is a major factor that differentiates it from other yeasts.

S. cerevisiae exists and grows in the haploid and diploid cellular forms. The haploid life cycle consists of mitosis, growth, and ultimately death, the latter more rapid under extremely stressful conditions. Diploid cells also undergo mitosis as well as growth, but in the same stressful circumstances can experience sporulation. Subsequent to sporulation, the cells undergo meiosis and produce a number of haploid spores. These haploid spores progress to mate.

Lactobacillus Fermentum

Lactobacillus fermentum is a Gram-positive species of bacterium in the genus Lactobacillus. It is associated with active dental caries lesions. It is also commonly found in fermenting animal and plant material. It has been found in sourdough. A few strains are considered probiotic or "friendly" bacteria in animals and at least one strain has been applied to treat urogenital infections in women. Some strains of lactobacilli formerly classified as Lactobacillus fermentum (such as RC-14) have since been reclassified as Lactobacillus reuteri. Commercialized strains of L. fermentum used as probiotics include PCCand ME-3. Lactobacillus fermentum belongs to the genus Lactobacillus. Species in this genus are used for a wide variety of applications. These applications include food and feed fermentation.

Conclusion

Morphology of the microorganism can be observed by microscope by oil immersion objectives which requirevery high resolving power for large magnifications. Besides, wet mount method also can be used in the examination of unstained bacteria.

Reference

· http://biology.clc.uc.edu/fankhauser/labs/microscope/Oil_Immersion.htm

· http://www.ruf.rice.edu/~bioslabs/methods/microscopy/oilimm.html

· http://biologicalmicroscopy.com/examination-of-unstained-bacteria.html

· http://microbewiki.kenyon.edu/index.php/Lactobacillus

· http://www.google.com.my/search?ix=sea&sourceid=chrome&ie=UTF-8&q=morphology+of+lactobacillus+fermentum