Exercise 2: Observing Bacteria Cultures In Yogurt

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Firstly, we created an incubator using a Styrofoam cooler with a removable lid and a small hole in the top which was used for placing a 7 watt light bulb in order to maintain a
Microbe growing temperature of 35-37° Celsius. We also monitored the temperature with the use of a thermometer.
A teaspoon of yogurt was then placed into a clean plastic container with lid. The container was then placed in the Styrofoam incubator, which was not disturbed for 24hrs.
After removing the yogurt from the incubator, a toothpick was used to obtain a sample of the yogurt, which was then smeared onto a clean slide. A cover slip was used to cover the slide, which was then observed for bacteria under the microscope with the resolutions 10x, 40x, and 100x with the use of immersion oil.
Observations were noted and we replaced that yogurt slide with the prepared, stained yogurt slide.
We compared and noted the observations between the two yogurt samples.

Exercise 3: Preparing and Observing a Blood
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Resolution - ability of a lens system to show fine details of the object being observed.

Contrast – When imaging specimens in the optical microscope, differences in intensity and/or color create image contrast, which allows individual features and details of the specimen to become visible. Contrast is defined as the difference in light intensity between the image and the adjacent background relative to the overall background intensity.

C. What is the purpose of immersion oil? Why does it work?

The purpose of immersion oil is to increase the resolution of a microscope. Immersion oil works well because it has almost the same refractive index as the glass slide; therefore, the refraction of light entering the lens becomes minimal and gives a better view of the specimen under the microscope.

Exercise 2: Observing Bacteria Cultures in Yogurt

A. Describe your observations of the fresh yogurt slide.

The microscope at a resolution of (10x) showed many black and white specks resembling coarse gravel or waves or bubbles. At a resolution of (40x) the sample resembled a dry scab, with a system of white veins going through. However, with the microscope at a resolution of (100x) the cells were seen moving in a stream like pattern with the presence of circular dark blots and grey

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