Domanda del libro di testo
What is the purpose of a counterstain in the acid-fast stain?
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Ch. 3 - Observing Microorganisms Through a Microscope
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398
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TOC.tableOfContents
- Ch. 1 - The Microbial World and You18
- Ch. 2 - Chemical Principles20
- Ch. 3 - Observing Microorganisms Through a Microscope18
- Ch. 7 - The Control of Microbial Growth20
- Ch. 9 - Biotechnology & DNA Technology20
- Ch. 10 - Classification of Microorganisms15
- Ch. 11 - The Prokaryotes: Domains Bacteria and Archaea14
- Ch. 12 - The Eukaryotes: Fungi, Algae, Protozoa, and Helminths17
- Ch. 13 - Viruses, Viroids, and Prions20
- Ch. 14 - Principles of Disease and Epidemiology21
- Ch. 15 - Microbial Mechanisms of Pathogenicity19
- Ch. 16 - Innate Immunity: Nonspecific Defenses of the Host20
- Ch. 17 - Adaptive Immunity: Specific Defenses of the Host20
- Ch. 18 - Practical Applications of Immunology20
- Ch. 19 - Disorders Associated with the Immune System19
- Ch. 20 - Antimicrobial Drugs19
- Ch. 21 - Microbial Diseases of the Skin and Eyes21
- Ch. 22 - Microbial Diseases of the Nervous System19
- Ch. 23 - Microbial Diseases of the Cardiovascular and Lymphatic Systems20
- Ch. 24 - Microbial Diseases of the Respiratory System20
- Ch. 25 - Microbial Diseases of the Digestive System20
- Ch. 26 - Microbial Diseases of the Urinary and Reproductive Systems19
- Ch. 27 - Environmental Microbiology20
- Ch. 28 - Applied and Industrial Microbiology19
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Tortora 14th EditionCh. 3 - Observing Microorganisms Through a MicroscopeProblema 8
Tortora 14th EditionCh. 3 - Observing Microorganisms Through a MicroscopeProblema 8Capitolo 3, Problema 8
What is the purpose of a decolorizer in the Gram stain? In the acid-fast stain?
Guida verificata passo dopo passo1
Understand that both the Gram stain and the acid-fast stain are differential staining techniques used to classify bacteria based on their cell wall properties.
In the Gram stain, the decolorizer (usually alcohol or acetone-alcohol) is applied after the primary stain (crystal violet) and the mordant (iodine). Its purpose is to selectively remove the crystal violet-iodine complex from Gram-negative bacteria, which have a thinner peptidoglycan layer, while Gram-positive bacteria retain the stain due to their thicker peptidoglycan layer.
In the acid-fast stain, the decolorizer (usually acid-alcohol) is used after the primary stain (carbol fuchsin). Its role is to remove the stain from non–acid-fast bacteria, which lack the waxy mycolic acid in their cell walls, while acid-fast bacteria retain the stain because their cell walls resist decolorization.
Recognize that the decolorizer is a critical step in both stains because it differentiates bacteria based on their cell wall composition by selectively removing the primary stain from certain groups.
Summarize that the decolorizer's purpose is to act as a selective agent that differentiates bacterial types by their ability to retain or lose the primary stain during the staining process.
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Gram Stain Procedure
The Gram stain is a differential staining technique used to classify bacteria into Gram-positive and Gram-negative based on their cell wall structure. It involves applying a primary stain, a mordant, a decolorizer, and a counterstain to distinguish bacterial types by color.
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04:57
Gram Stain
Role of Decolorizer in Gram Stain
In the Gram stain, the decolorizer (usually alcohol or acetone-alcohol) selectively removes the primary stain from Gram-negative bacteria by dissolving their outer membrane and washing out the crystal violet-iodine complex. This step differentiates Gram-negative (colorless after decolorization) from Gram-positive bacteria (retain purple color).
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04:57Gram Stain
Decolorizer Function in Acid-Fast Stain
In the acid-fast stain, the decolorizer (acid-alcohol) removes the primary stain from non–acid-fast cells but not from acid-fast bacteria, which have waxy mycolic acid in their cell walls. This selective decolorization allows acid-fast bacteria to retain the red stain, distinguishing them from non–acid-fast cells.
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05:30Simple Staining Basic & Acidic Dyes
Pratica correlata
Domanda del libro di testo
Which of the following is not a modification of a compound light microscope?
a. Brightfield microscopy
b. Darkfield microscopy
c. Electron microscopy
d. Phase-contrast microscopy
e. Fluorescence microscopy
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Domanda del libro di testo
Assume that you are viewing a Gram-stained field of red cocci and blue rods through the microscope. You can safely conclude that you have
a. Made a mistake in staining
b. Two different species
c. Old bacterial cells
d. Young bacterial cells
e. None of the above
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Domanda del libro di testo
Assume you stain Clostridium by applying a basic stain, carbolfuchsin, with heat, decolorizing with acid-alcohol, and counterstaining with an acidic stain, nigrosin. Through the microscope, the endospores are 1, and the cells are stained 2.
a. 1—red; 2—black
b. 1—black; 2—colorless
c. 1—colorless; 2—black
d. 1—red; 2—colorless
e. 1—black; 2—red
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Domanda del libro di testo
In 1996, scientists described a new tapeworm parasite that had killed at least one person. The initial examination of the patient’s abdominal mass was most likely made using:
a. Brightfield microscopy
b. Darkfield microscopy
c. Electron microscopy
d. Phase-contrast microscopy
e. Fluorescence microscopy
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Domanda del libro di testo
Fill in the following table regarding the Gram stain:
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