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Questions and Answers
What is the primary staining step in the Gram stain procedure?
What is the primary staining step in the Gram stain procedure?
What color do Gram-positive cells typically appear as under the microscope?
What color do Gram-positive cells typically appear as under the microscope?
What is the purpose of using Acid-Fast stains in microbiology?
What is the purpose of using Acid-Fast stains in microbiology?
What is the approximate size of a bacterial cell?
What is the approximate size of a bacterial cell?
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Which part of the microscope controls the amount of light that enters the objective lens?
Which part of the microscope controls the amount of light that enters the objective lens?
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What is the purpose of using stains in microscopy?
What is the purpose of using stains in microscopy?
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Which type of cell has ribosomes that are 80S?
Which type of cell has ribosomes that are 80S?
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Which bacterial type is unaffected by penicillin and lysozyme due to the lack of a cell wall?
Which bacterial type is unaffected by penicillin and lysozyme due to the lack of a cell wall?
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Which bacterial type stains purple/violet due to its thick peptidoglycan layer?
Which bacterial type stains purple/violet due to its thick peptidoglycan layer?
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What is the main function of the outer membrane in Gram-negative bacteria?
What is the main function of the outer membrane in Gram-negative bacteria?
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A bacterial cell is typically larger than 3 micrometers in size.
A bacterial cell is typically larger than 3 micrometers in size.
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The compound light microscope uses only one lens for magnification.
The compound light microscope uses only one lens for magnification.
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Capsules of bacteria do not stain because they have a strong positive charge.
Capsules of bacteria do not stain because they have a strong positive charge.
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Crystal violet forms crystals outside the cell in Gram positive bacteria.
Crystal violet forms crystals outside the cell in Gram positive bacteria.
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Acid-Fast stains are used to detect organisms that easily take up stains.
Acid-Fast stains are used to detect organisms that easily take up stains.
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Capsule staining involves darkening the capsule area to make it less visible.
Capsule staining involves darkening the capsule area to make it less visible.
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Eukaryotic cells are typically smaller in size compared to prokaryotic cells.
Eukaryotic cells are typically smaller in size compared to prokaryotic cells.
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Gram-positive bacteria have a thin peptidoglycan layer protected by an outer membrane.
Gram-positive bacteria have a thin peptidoglycan layer protected by an outer membrane.
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Mycoplasma pneumoniae has a cell wall composed of peptidoglycan.
Mycoplasma pneumoniae has a cell wall composed of peptidoglycan.
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Penicillin is an antibiotic that targets peptidoglycan synthesis in bacterial cell walls.
Penicillin is an antibiotic that targets peptidoglycan synthesis in bacterial cell walls.
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What is the function of the immersion oil in a microscope?
What is the function of the immersion oil in a microscope?
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Explain the purpose of using stains in microscopy and provide an example of how stains work.
Explain the purpose of using stains in microscopy and provide an example of how stains work.
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Why do bacterial capsules not stain during capsule staining procedures?
Why do bacterial capsules not stain during capsule staining procedures?
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Explain the difference between Gram positive and Gram negative cells in terms of the cell wall composition and staining characteristics.
Explain the difference between Gram positive and Gram negative cells in terms of the cell wall composition and staining characteristics.
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Describe the procedure for Acid-Fast staining and explain why it is used in microbiology.
Describe the procedure for Acid-Fast staining and explain why it is used in microbiology.
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What is the purpose of Endospore staining? Describe the staining procedure used for Endospores.
What is the purpose of Endospore staining? Describe the staining procedure used for Endospores.
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Which type of cell has a true nucleus?
Which type of cell has a true nucleus?
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Which bacterial organism is considered Prokaryotic?
Which bacterial organism is considered Prokaryotic?
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What is the specific target of the antibiotic Penicillin?
What is the specific target of the antibiotic Penicillin?
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Which of the following types of bacteria have LPS endotoxin?
Which of the following types of bacteria have LPS endotoxin?
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The total magnification in a microscope is the product of the magnifying power of the ocular lens and the ______ lens.
The total magnification in a microscope is the product of the magnifying power of the ocular lens and the ______ lens.
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Immersion oil has the same refractive index as ______.
Immersion oil has the same refractive index as ______.
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Stains in microbiology are used to provide ______ to specimens.
Stains in microbiology are used to provide ______ to specimens.
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Gram Stain Procedure was developed by __________.
Gram Stain Procedure was developed by __________.
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The Gram Stain procedure uses Crystal Violet as the primary _________.
The Gram Stain procedure uses Crystal Violet as the primary _________.
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Gram Negative cells generally appear pink/red after counterstaining with _________.
Gram Negative cells generally appear pink/red after counterstaining with _________.
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The staining agent adheres to and coats the otherwise thin flagella, making them visible with the light microscope. This process is known as Flagella ______.
The staining agent adheres to and coats the otherwise thin flagella, making them visible with the light microscope. This process is known as Flagella ______.
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Bacteria reproduce through ______ fission.
Bacteria reproduce through ______ fission.
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Eukaryotic cells possess a true ______ containing many linear chromosomes.
Eukaryotic cells possess a true ______ containing many linear chromosomes.
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Bacterial Cell Wall is composed of ______.
Bacterial Cell Wall is composed of ______.
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Match the following units of measurement with their corresponding values in powers of 10:
Match the following units of measurement with their corresponding values in powers of 10:
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Match the following microscope components with their functions:
Match the following microscope components with their functions:
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Match the following staining concepts with their descriptions:
Match the following staining concepts with their descriptions:
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Match the cell type with the correct description:
Match the cell type with the correct description:
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Match the bacterial arrangement with the correct bacteria:
Match the bacterial arrangement with the correct bacteria:
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Match the staining technique with its specific characteristic:
Match the staining technique with its specific characteristic:
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Match the bacterial type with the correct cell wall description:
Match the bacterial type with the correct cell wall description:
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Match the antibiotic with its specific target in bacterial cells:
Match the antibiotic with its specific target in bacterial cells:
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Match the bacteria classification with its characteristic under the microscope:
Match the bacteria classification with its characteristic under the microscope:
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Match the primary stain with the corresponding staining procedure:
Match the primary stain with the corresponding staining procedure:
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Which type of bacteria is unaffected by penicillin and lysozyme due to the lack of a cell wall?
Which type of bacteria is unaffected by penicillin and lysozyme due to the lack of a cell wall?
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What is the main function of teichoic acid in bacterial cell walls?
What is the main function of teichoic acid in bacterial cell walls?
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Which enzyme specifically targets the peptidoglycan-making enzyme in bacterial cells?
Which enzyme specifically targets the peptidoglycan-making enzyme in bacterial cells?
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Which bacterial arrangement is characteristic of Staphylococcus aureus?
Which bacterial arrangement is characteristic of Staphylococcus aureus?
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Which part of the bacterial cell contains one circular chromosome and possible extra DNA known as plasmids?
Which part of the bacterial cell contains one circular chromosome and possible extra DNA known as plasmids?
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Flagella staining involves making the flagella invisible under the light microscope.
Flagella staining involves making the flagella invisible under the light microscope.
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Eukaryotic cells typically reproduce through binary fission.
Eukaryotic cells typically reproduce through binary fission.
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Prokaryotic cells lack membrane-enclosed organelles.
Prokaryotic cells lack membrane-enclosed organelles.
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Gram-positive bacteria have a thin peptidoglycan layer protected by lipopolysaccharides (LPS).
Gram-positive bacteria have a thin peptidoglycan layer protected by lipopolysaccharides (LPS).
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Eukaryotic cells are generally smaller in size compared to prokaryotic cells.
Eukaryotic cells are generally smaller in size compared to prokaryotic cells.
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Which type of bacteria lacks a cell wall?
Which type of bacteria lacks a cell wall?
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What is the specific target of the antibiotic Penicillin?
What is the specific target of the antibiotic Penicillin?
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What is the main function of teichoic acid in bacterial cell walls?
What is the main function of teichoic acid in bacterial cell walls?
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What process do most prokaryotes/bacteria use for division?
What process do most prokaryotes/bacteria use for division?
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Which staining technique makes flagella visible under the light microscope?
Which staining technique makes flagella visible under the light microscope?
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Which cell type has a ______ nucleus? A.Prokaryotic B.Eukaryotic C.Both D.Neither
Which cell type has a ______ nucleus? A.Prokaryotic B.Eukaryotic C.Both D.Neither
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Which cell type has ______? A.Prokaryotes B.Eukaryotes C.Both D.Neither
Which cell type has ______? A.Prokaryotes B.Eukaryotes C.Both D.Neither
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Which cell type has ______? A.Prokaryotes B.Eukaryotes C.Both D.Neither
Which cell type has ______? A.Prokaryotes B.Eukaryotes C.Both D.Neither
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The bacterial organism that you are writing your report on is considered _____. A.Prokaryotic B.Eukaryotic C.Both D.Neither
The bacterial organism that you are writing your report on is considered _____. A.Prokaryotic B.Eukaryotic C.Both D.Neither
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Which of the following types of bacteria lacks a cell wall? A.Gram Positive B.Gram Negative C.Both D.______ of the above
Which of the following types of bacteria lacks a cell wall? A.Gram Positive B.Gram Negative C.Both D.______ of the above
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Match the primary characteristics of Prokaryotic Cells and Eukaryotic Cells:
Match the primary characteristics of Prokaryotic Cells and Eukaryotic Cells:
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Match the bacterial cell types with their ribosome composition:
Match the bacterial cell types with their ribosome composition:
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Match the bacterial cell types with their mode of reproduction:
Match the bacterial cell types with their mode of reproduction:
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Match the bacterial arrangements with their corresponding bacteria:
Match the bacterial arrangements with their corresponding bacteria:
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Match the components of the bacterial cell envelope with their descriptions:
Match the components of the bacterial cell envelope with their descriptions:
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Study Notes
Microscope and Measurement
- The microscope includes compound light, electron microscope, and others like atomic-force microscopy.
- The compound light microscope uses many lenses: ocular 10x, condenser (condenses light), objectives (scanning 4x, low 10x, high 40x, oil 100x).
- The total magnification is the product of the magnifying power of the ocular lens and the objective lens.
- The iris diaphragm lever controls the amount of light that enters the objective lens.
- The light source rheostat controls the brightness of the light.
Measurement Units
- deci: Tenth (10^-1)
- centi: Hundredth (10^-2)
- milli: Thousandth (10^-3)
- micro: Millionth (10^-6)
- nano: Billionth (10^-9)
- pico: Trillionth (10^-12)
- The approximate size of a bacterial cell is 3 μm (micrometers).
Stains
- Stains contain both (+) and (-) ions but are slightly charged.
- Basic Dyes are (+) and Acidic Dyes are (-).
- Stains are used to create contrast for better visibility.
- Background stains are used to see capsules, which don't stain (non-ionic).
Gram Stain
- Gram stain is a differential stain that separates bacteria into two major groups: Gram-positive and Gram-negative.
- Gram-positive bacteria:
- Contain lots of peptidoglycan in the cell wall.
- Crystal violet forms crystals within the cell.
- Retain the crystal violet stain after decolorization.
- Appear purple/blue under the microscope.
- Example: Staphylococcus aureus.
- Gram-negative bacteria:
- Possess a protective outer membrane.
- Contain less peptidoglycan in the cell wall.
- Crystal violet washes off more easily during decolorization.
- Appear pink/red after counterstaining with safranin.
- Example: Escherichia coli.
Other Stains
- Acid-Fast Stain: Used to detect organisms that do not easily take up stains, particularly members of the genus Mycobacterium.
- Endospore Stain: Used to stain endospores, a type of dormant cell that does not readily take up the stains.
- Flagella Staining: Used to highlight the structure of flagella.
- Capsule Staining: Used to create a clear halo around capsule bacteria or fungal cells.### Gram Stain Procedure
- The Gram stain procedure involves crystal violet as the primary stain, iodine as a mordant, decolorization with alcohol or alcohol acetone, and counterstaining with safranin.
- The Gram stain differentiates bacteria into two groups: Gram-positive and Gram-negative.
Gram-Positive Bacteria
- Gram-positive bacteria have a thick peptidoglycan layer in their cell walls.
- Crystal violet forms crystals within the cell and is retained during decolorization, resulting in a purple/blue appearance under the microscope.
- Examples of Gram-positive bacteria include Staphylococcus aureus.
Gram-Negative Bacteria
- Gram-negative bacteria have a protective outer membrane and less peptidoglycan in their cell walls.
- Crystal violet is washed off during decolorization, resulting in a pink/red appearance after counterstaining with safranin.
- Examples of Gram-negative bacteria include Escherichia coli.
Acid-Fast Stain
- The acid-fast stain is used for bacteria with a waxy coat, such as Mycobacterium leprae and M. tuberculosis.
- The procedure involves using red carbolfuchsin as the primary stain, 3% acid alcohol as the decolorizing agent, and methylene blue as the counterstain.
- Acid-fast cells appear red, while non-acid-fast cells appear blue.
Endospore Stain
- The endospore stain is used to detect endospores, which are resistant to dye penetration.
- The procedure involves using malachite green with steam as the primary stain, followed by safranin as the counterstain.
Flagella Staining
- Flagella staining involves using very thin coats of the staining solution to highlight the structure of flagella.
Capsule Staining
- Capsule staining involves using background staining to create a clear halo around capsule bacteria or fungal cells.
Stain Characteristics
- Simple stains use a basic dye to increase contrast between cells and the background.
- Differential stains use a multistep procedure to distinguish between different groups of microorganisms.
- Special stains use a specific procedure to stain specific cell structures.
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Description
Test your knowledge of metric prefixes and microscopy concepts with this quiz. Questions cover the meanings of deci, centi, milli, micro, nano, and pico prefixes as well as features of compound light microscopes and electron microscopes.
