Questions and Answers
Staining is an auxiliary technique used in microscopy to enhance ______ in the microscopic image.
contrast
Fixation is used to preserve the ______ of the cells or tissue involved as much as possible.
shape
The hanging drop technique enables viewing of size, shape, arrangement and ______ of live microorganisms in fluid media.
motility
Microbiologists commonly stain bacterial cells because the cytoplasm lacks ______, making it hard to see the cells.
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The hanging drop technique requires the use of special ______ slides.
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Low power low curvature lenses could be made with minimal ______.
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The maximum resolution that Abbe was able to achieve is about 10 times better than the resolution ______ had achieved.
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This resolution of 0.2 microns or 200 nanometers is a physical limit imposed by the ______ of light.
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Carl Zeiss began his own business in the German university town of ______.
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Between 1846 and 1866, microscopes of uniformly high quality were built in Zeiss' workshop in accordance with very strict rules of ______.
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The first genuine compound microscope produced was called the ______.
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Zeiss took great pride in what had become a prosperous ______.
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Zeiss also was aware that competition from other microscope manufacturers would eventually bypass his ______ if he failed to continue to produce innovations.
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The main advantages of staining include providing contrast between microorganisms and their ______.
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Staining permits the study of internal structures of the bacterial cell, such as the cell ______, vacuoles or nuclear bodies.
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Heat fixing involves passing the slide over the bunsen flame quickly ______ times.
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Simple staining is the use of a single stain to colour a bacterial ______.
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Bacteria have chromophores that are positively charged, creating an attraction between the cationic chromatophores and the ______.
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Acidic dyes, such as eosine, will not stain bacteria due to ______ repelling forces.
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The staining times for most simple stains are usually from 30 seconds to ______ minutes.
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Crystal violet and carbol fuschin are examples of ______ dyes.
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Acid fast stain results can confirm the presence of the bacteria known as ______, which is responsible for causing tuberculosis.
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Fluorochrome acid fast staining is used in conjunction with the ______ method in laboratories.
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Fluorochrome stained slides can be examined with ______ or 100X magnification.
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The procedure starts by pouring ______ on the slide and heating carefully until steam rises.
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Acid fast organisms, e.g., ______ and Mycobacterium leprae stain well.
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Structural staining allows the observation of certain ______ on bacteria.
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Bacteria belonging to the genera ______ and Clostridium produce extremely heat resistant structures called endospores.
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The resistance of endospores to heat and chemicals is due primarily to a thick, tough ______ coat.
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The malachite green-Schaeffer and Fulton method commonly used by most ______.
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Endospore stains ______ but the rest of the cell stains light red.
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To prepare a thin smear, place the slide on a staining rack above boiling ______.
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Counter stain with ______ for 30 seconds.
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For capsule staining, a small drop of ______ ink is mixed with bacterial culture.
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Allow the slide over the flame to fix after adding few drops of ______ alcohol.
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In flagella staining, heat the ______ in a test tube to boiling point.
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The capsule will appear as haloes in blue ______ of bacterium under microscope.
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Study Notes
Microscope Development and Light Collection
- Low power low curvature lenses minimize aberration, improving microscope performance.
- Ernst Abbe in the 1870s maximized light collection with water and oil immersion lenses.
- Abbe achieved a resolution of 0.2 microns (200 nanometers), significantly better than Leeuwenhoek's earlier resolution.
- Carl Zeiss started a business in Jena, Germany, focused on high-quality microscopy instruments.
- Zeiss produced the first genuine compound microscope, the Stativ 1, combining functionality with optical refinement.
Staining Techniques in Microscopy
- Staining enhances contrast in microscopic images and highlights biological structures.
- Stains are commonly used in biology and medicine for tissue sample visualization.
Fixation Process
- Fixation preserves the shape of cells or tissues and prepares them for staining.
- Heat fixation kills and adheres cells, making them permeable for stain uptake.
Hanging Drop Technique
- Allows observation of live bacteria, assessing size, shape, arrangement, and motility.
- Involves a specialized slide, with a loopful of suspension placed under a cover slip and oil droplets for retaining moisture.
Microbial Staining Advantages
- Enhances visibility of microorganisms against backgrounds.
- Facilitates internal structure studies within bacterial cells.
- Allows for higher magnifications in observations.
Staining Process
- Smear preparation involves mixing bacteria with water, spreading thinly, air drying, and heat fixing over a flame.
Simple Staining
- Uses a single stain to color bacterial cells; basic dyes are preferred due to the slight negativity of bacteria.
- Acidic dyes do not effectively stain as they repel due to electrostatic forces.
- Simple staining durations range from 30 seconds to 2 minutes, varying by dye affinity.
Acid-Fast Staining Method
- Confirms presence of Mycobacterium tuberculosis.
- Fluorochrome acid-fast staining is combined with the Ziehl-Neelsen method for efficient scanning.
- Procedure includes heating carbol fuchsin, decolorizing with acid alcohol, and counterstaining.
Structural Staining
- Structural staining allows differentiation of specific bacterial structures that may be antigenic or act as endotoxins.
- More complex than simple staining, employing multiple stains for contrast within organisms.
Endospore Staining
- Identifies heat-resistant structures produced by Bacillus and Clostridium genera.
- Commonly uses the malachite green-Schaeffer and Fulton method for visualization.
Capsule Staining
- Involves mixing bacterial culture with Indian ink to visualize capsules.
- Haloes appear around bacteria, indicating presence of protective capsules against immune responses.
Flagella Staining
- Involves heat fixing a bacterial suspension, followed by mordant treatment to visualize flagella.
- A silver solution enhances visibility, showing dark or metallic sheen on flagella under microscopy.
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Description
Explore the principles of low power and low curvature lenses in microscopy as discussed by Ernst Abbe. Learn how these lenses minimize aberration and enhance light collection for optimal microscope performance. This quiz delves into the historical context and scientific laws that underpin modern microscopy.
