Questions and Answers
What is the shape of the bacteria in the first row?
Why are the bacteria in the third row viewed using dark field microscopy?
What is the term for a single bacterium with a spherical shape?
What is the appearance of the bacteria in the second row?
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Why are the bacteria in the first row purple in color?
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What is the term for multiple bacteria with a spherical shape?
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Why is it necessary to view the bacteria in the third row using a different method?
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What is the shape of the bacteria in the third row?
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What is the term used to describe a single rod-shaped bacterium?
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What is the purpose of the Gram stain in studying bacteria?
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What is the characteristic of the cell wall in Gram positive bacteria?
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What is the function of the lipopolysaccharide layer in Gram negative bacteria?
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What is the term used to describe a single spiral-shaped bacterium?
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What is the main difference between the cell walls of Gram positive and Gram negative bacteria?
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What is the purpose of the capsule layer in bacterial cells?
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What is the term used to describe the combination of sugar chains and peptides in bacterial cell walls?
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What is the main component of the outer membrane in Gram negative bacteria?
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What is the term used to describe the staining result of Gram positive bacteria?
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What is the layer above the plasma membrane in a bacterium?
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What is the name of the space between the plasma membrane and the peptidoglycan layer?
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What is the reason why Gram negative bacteria stain pink?
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What is the purpose of the Gram stain?
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What is the characteristic of the peptidoglycan layer in Gram positive bacteria?
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What is the name of the substance used to restain Gram negative bacteria?
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What is the location of the polysaccharides in a bacterium?
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What is the term for the region next to the plasma membrane?
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Study Notes
Bacteria Shapes
- Bacteria can have different shapes, including:
- Coccus (singular) or Cocci (plural): spherical shape
- Bacillus (singular) or Bacilli (plural): rod-shaped
- Spirochete (singular) or Spirilla (plural): spiral-shaped
Gram Staining
- The Gram stain is a special stain used to distinguish between bacteria
- It stains the outside of the bacteria
- If the stain is retained, the bacteria is Gram positive and appears purple
- If the stain is washed off and restained with Safranin, the bacteria is Gram negative and appears pink
Gram Positive Bacteria
- Have a thick peptidoglycan layer in their cell wall
- The peptidoglycan layer is made up of long chains of sugars (glycan) connected by proteins (peptide)
- This layer is responsible for retaining the Gram stain, making the bacteria appear purple
- Gram positive bacteria also have a plasma membrane and a capsule or slime layer
Gram Negative Bacteria
- Have a thin peptidoglycan layer in their cell wall
- The thin peptidoglycan layer is washed off by the Gram stain, making the bacteria appear pink after restaining with Safranin
- Gram negative bacteria have an outer membrane, a lipopolysaccharide (LPS) layer, and a capsule or slime layer
- The LPS layer is composed of lipids and polysaccharides
Cell Wall Structure
- Gram positive bacteria have a thick peptidoglycan layer, a plasma membrane, and a capsule or slime layer
- Gram negative bacteria have a thin peptidoglycan layer, an outer membrane, an LPS layer, and a capsule or slime layer
Key Differences
- Gram positive bacteria have a thick peptidoglycan layer, while Gram negative bacteria have a thin peptidoglycan layer
- Gram positive bacteria retain the Gram stain, while Gram negative bacteria are washed off and restained with Safranin
- The cell wall structure of Gram positive and Gram negative bacteria differs significantly
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Description
Examine bacteria samples under a microscope and identify their characteristics, including color and shape, to differentiate between them.
