Micro Lab Quiz 1 - Lecture notes 1 PDF

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2-1 Ubiquity of Microorganisms KEY TERMS ● Ubiquity ○ Microorganisms can be found anywhere that other forms of life exist ○ Ubiquitous means they are present nearly everywhere ○ Ubiquitous organisms can be found: ■ Soil ■ Water ■ Plants ■ Animals ● Agar plates ● Culture ○ Media containing living microbes ● Mixed culture ○ Multiple species growing on an agar plate ○ Can identify species based on differering colony morphology ● Colony ○ A colony is defined as a visible mass of microorganisms all originating from a single mother cell, therefore a colony constitutes a clone of bacteria all genetically alike ○ Visible mass of identical cells ● Isolated colony ○ Not contacting other colonies ○ A portion of it can be transferred to a sterile medium to produce a pure culture of the species ● Pure culture ○ Contains only one living microbe ○ Usually grown in a broth or a slanted medium QUESTIONS: ● What was the purpose of incubating the unopened plates? What is an appropriate name for these plates? ○ To be used as a negative control, nothing should grow on these plates. ● If growth appears on both unopened plates, what are some likely explanations? ○ Most likely occurred from contamination, or when the media was made ● What if growth appears on only one plate? How does growth on the unopened plates affect the reliability of the other plates? ● Why were the specific types of exposure (air, hair, tabletop, etc.) chosen for this exercise? ○ Major sources of environmental contamination

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Why were you asked to incubate the plates at two different temperatures? Be specific. What is the likely source (reservoir) of organisms that grew at 37℃, and how do you think they survive at room temperature without nutrients? ○ Capture ubiquity of microbes, some grow fast at room temperature, others grow fast at body temp. Source for microbes at 37C= human body. Did you get different appearing colonies on plates 2 and 3? If so explain why. ○ Yes because of more growth at a higher temperature. Clarity of an image is called resolution

2-3 Microscopy Simulation ●

Why do we have to start with the lowest magnification to examine a new slide? - It is easier to focus on the specimen

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Which of the following chemicals was not used to stain this tissue? - Eosin to stain eosinophilic structures in various shades of red, pink, and orange.

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What are the macroscopic structures, which point into the lumen (white), called? - Villi

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What is the aniline blue-stained structure in the sample? It is a stringy mass beneath the intestinal epithelium that extends into the villi. - Extracellular tissue

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What is the connective tissue and extracellular matrix composed of? - All of these

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What does the light red layer between the white lumen and blue lamina propria contrast of? - Epithelial cells

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What type of epithelium is present in the small intestine? - Simple columnar epithelium

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What are the oval-shaped structures that can be found all over the slide? - Nuclei

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Click on the explore button below to count the number of lymphocytes relative to the other epithelial cells. Is there an increased number of lymphocytes in the epithelium? - No, the percentage of lymphocytes does not exceed 10%

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Why is it not possible to achieve a higher resolution in the light microscope? - The wavelength of visible light is too long

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How could we build a microscope with a higher resolution? - all of these answers are good ideas for a high-resolution microscope

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Move the image and have a closer look at the edge of the epithelium. Try to identify the basal side facing toward the lamina propria in the apical side bordering the lumen. Which of the statements below is correct? - The basal side is facing towards the left side of the screen

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What are the three different cells called? - Absorptive enterocytes, brush cells, and goblet cells

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What structure seals the space between two cells and makes it impermeable? - Tight junctions

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Which of the following statements is not true for DAPI staining? - The light source only emits UV light

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Why is the microscopy slide shining with a blue light? - The green fluorescent dye attached phalloidin is excited by blue light and emits green light

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What can you conclude from the distribution of the red fluorescence? - The virus seems to accumulate in certain areas

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A transmission electron microscope allows us to see structures at a high ___. if we want to take images with a high ___ we usually use fluorescence microscopy. - Resolution , contrast

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Figure out where the retroviruses accumulate. - They accumulate around lymphocytes

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The Mallory staining method makes use of three dyes. What are they and what do they stain? 1. Aniline blue - Stains connective tissue blue - Collagen = bright or light blue 2. Orange 6 - Stains proteins (therefore = the cytoplasm) pinkish - Cytoplasm, ketatin, and erythrocytes = bright red/orange 3. Fuchsin - Stains DNA/RNA dark red/maroon - Nuclei = dark red

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Light Microscopy - Light microscopy is the most commonly used microscopy technique. It often requires staining of the specimen to be able to visualize the structures of interest. - Light microscopy is limited to a minimal resolution of approximately 200 nm. The minimal resolution is defined as the distance between two points that are still distinguishable as two separate entities. - The resolution is limited by physical properties of light and the lens of the microscope. On one hand, the wavelength of the light limits the resolution; the shorter the wavelength the better the resolution. - On the other hand, the aperture value of the objective lens limits the resolution. To tune the aperture value to its limits you can place a drop of immersion oil between the cover slip of the slide and the objective lens. Without the immersion oil, the light is refracted when it moves from glass to air and back into the glass of the objective lens. If you use immersion oil with the same optical density as glass, this effect can be diminished and the minimal resolution can be achieved. Fluorescence Microscopy - Fluorescence microscopes take advantage of the difference in emission and transmission wavelengths of fluorophores to produce high contrast images. - Fluorescent microscopes are equipped with a carousel of filter cubes. The cubes consist of an excitation filter, a dichroic mirror, and an emission filter. The combination of these filters matches the excitation and emission wavelengths of certain fluorophores. Therefore, the filter cubes are specific for a certain stain. - There are several fluorescent dyes that can freely diffuse into a living cell. Other fluorophores include fluorescent protein tags such as green fluorescent protein

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(GFP) or SNAP tags that can be expressed transgenically and fluorescently labeled antibodies that bind to molecules of interest in the cell. Therefore, fluorescent microscopy can be used to visualize microscopic cellular processes that are impossible to visualize with other microscopy techniques.

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3-3 Eukaryotic Microbes I.

Unikonta A. Amoeba B. Rhizopus

C. Aspergillus

D. Penicillium

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Excavata A. Trypanosoma

B. Trichomonas vaginalis

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SAR A. Plasmodium falciparum

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Archaeplastida

12-4 Parasitic Helminths...