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Questions and Answers
Who was among the first to see microorganisms?
Who was among the first to see microorganisms?
Anton Van Leuwenhoek
What did Anton Van Leuwenhoek call microorganisms?
What did Anton Van Leuwenhoek call microorganisms?
animalcules
Microscopy is defined as the technology of making large objects visible to the human eye.
Microscopy is defined as the technology of making large objects visible to the human eye.
False
What is the name of the commonly used microscope?
What is the name of the commonly used microscope?
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Light microscopy involves the use of visible light to make specimens observable.
Light microscopy involves the use of visible light to make specimens observable.
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What are the different types of light microscopy?
What are the different types of light microscopy?
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What is the function of a condenser in a light microscope?
What is the function of a condenser in a light microscope?
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Which type of microscopy uses ultraviolet light to excite molecules and produce fluorescence?
Which type of microscopy uses ultraviolet light to excite molecules and produce fluorescence?
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Electron microscopy uses light instead of electrons to provide a higher resolving power.
Electron microscopy uses light instead of electrons to provide a higher resolving power.
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Which type of electron microscopy is used to visualize the internal structure of microbes?
Which type of electron microscopy is used to visualize the internal structure of microbes?
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Which type of electron microscopy is used to reveal the surface of specimens?
Which type of electron microscopy is used to reveal the surface of specimens?
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What is the name of the staining technique that utilizes crystal violet and iodine to differentiate bacteria?
What is the name of the staining technique that utilizes crystal violet and iodine to differentiate bacteria?
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Which type of bacteria retain the crystal violet stain during Gram staining?
Which type of bacteria retain the crystal violet stain during Gram staining?
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Which type of bacteria lose the crystal violet stain during Gram staining?
Which type of bacteria lose the crystal violet stain during Gram staining?
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Which staining technique is used to identify acid-fast bacteria?
Which staining technique is used to identify acid-fast bacteria?
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Acid-fast bacteria have a waxy cell wall that resists decolorization by acids.
Acid-fast bacteria have a waxy cell wall that resists decolorization by acids.
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What is the main purpose of negative staining?
What is the main purpose of negative staining?
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Flagella are thin structures visible under light microscope.
Flagella are thin structures visible under light microscope.
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What is the main function of flagella?
What is the main function of flagella?
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Endospores are a reproductive structure formed by some bacteria.
Endospores are a reproductive structure formed by some bacteria.
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What are some of the medical significance of endospores?
What are some of the medical significance of endospores?
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Staining techniques are used to make microorganisms stand out against their background.
Staining techniques are used to make microorganisms stand out against their background.
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What are the two main types of dyes used in staining?
What are the two main types of dyes used in staining?
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Simple stains use a single dye to reveal basic cell shapes and arrangements.
Simple stains use a single dye to reveal basic cell shapes and arrangements.
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Differential stains use multiple dyes to distinguish between different types of organisms or cell structures.
Differential stains use multiple dyes to distinguish between different types of organisms or cell structures.
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Special stains are used to identify specialized structures of microorganisms.
Special stains are used to identify specialized structures of microorganisms.
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Wet mounts allow visualization of living microorganisms.
Wet mounts allow visualization of living microorganisms.
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Smears are used to study the structure of non-living microorganisms.
Smears are used to study the structure of non-living microorganisms.
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Heat fixation is used to kill organisms and adhere them to the slide.
Heat fixation is used to kill organisms and adhere them to the slide.
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Heat fixation alters microorganisms to enhance their ability to accept stain.
Heat fixation alters microorganisms to enhance their ability to accept stain.
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Study Notes
Microscopy and Staining
- Microscopy is the technology of making very small things visible to the human eye.
- Anton Van Leeuwenhoek (Holland), in 1600, was likely the first to observe microorganisms (bacteria and protozoa).
- He created a microscope capable of magnifying objects between 100 and 300 times their original size.
- He sent a letter to the Royal Society of London describing his findings, calling the microorganisms "animalcules".
- He created 419 microscopes with samples, and 100 were sent to the Royal Society.
- Following his death in 1723, the field of microbiology slowed down.
- By studying his letters, the existence of microbes was revealed to the scientific community.
Light Properties
- Wavelength (λ) is measured in micrometres (µm).
- The sun produces a continuous spectrum of electromagnetic radiation.
- White light is a combination of visible light.
- Resolving power (RP) is the ability of an optical instrument to display fine details in a specimen; short wavelengths are useful for greater resolution.
- Visible light (500nm) cannot resolve objects separated by less than 220nm.
- Ultraviolet light (100-400nm) can resolve separations as small as 110nm.
Light properties
- Light can be reflected, transmitted, or absorbed by objects.
- Reflection is when light bounces back, and transmission is the passage of light through an object.
- Absorption is when light is taken in by an object
- Refraction is the bending of light when it passes through different mediums (of differing densities).
- Diffraction is the bending of waves as they pass through small openings.
Compound Light Microscopy
- It uses visible light to observe specimens.
- There are several complex designs for specimens.
- Key parts of a microscope include the ocular, objective, stage, condenser, focusing knobs, and light source.
Light Microscopy Types
- Light microscopy is any type of microscope that uses visible light to create observable specimens.
- Modern designs aim to improve resolution and contrast.
- Brightfield, darkfield, phase-contrast, and Nomarski microscopy are examples.
- Different staining techniques are used to highlight specific structures or substances within the specimen, which help to increase contrast and aid in classification. These techniques include Gram staining, Ziehl-Neelsen acid-fast staining, negative staining, flagellar staining, and endospore staining.
Staining Techniques
- Staining techniques create contrast between the specimens and their background.
- Dyes are cationic (positive charge) or basic (Methylene blue, crystal violet, safranin) and are attracted to negatively charged cell components (e.g., cell membranes).
- Simple stains reveal cell shapes and arrangements (using a single dye).
- Differential stains distinguish between kinds of organisms or parts of an organism (using multiple dyes).
- Special stains highlight specialized structures.
- Gram staining differentiates bacteria based on their cell wall structure (Gram-positive vs. Gram-negative).
- Ziehl-Neelsen acid-fast staining identifies acid-fast bacteria (e.g., Mycobacterium).
- Negative staining creates a dark background allowing capsules to show up as clear areas.
- Flagellar staining coats thin flagella, allowing visualization using silver or red dyes.
- Endospore staining uses Malachite green to highlight endospores that are resistant to heat.
Electron Microscopy (EM)
- Electron microscopy overcomes the resolution limitations of light microscopes.
- It replaces light with electrons for higher resolution.
- Transmission electron microscopy (TEM) examines internal structures.
- Scanning electron microscopy (SEM) examines the surface of specimens.
Specimen Preparation
- Wet mounts: Specimens are placed in a liquid medium on a slide for viewing living samples.
- Smears: Specimens are spread onto a slide, dried, and heat-fixed for viewing non-living samples.
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Description
Explore the fundamentals of microscopy and the properties of light in this quiz. Discover the historical significance of Anton Van Leeuwenhoek's discoveries and understand the basic principles of light measurements. Test your knowledge on the key concepts that form the foundation of microbiology and optics.
