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Questions and Answers
What is a characteristic feature of prokaryotic cells compared to eukaryotic cells?
What is a characteristic feature of prokaryotic cells compared to eukaryotic cells?
- Presence of visible endoplasmic reticulum
- More complex cellular structure
- Presence of a nuclear membrane
- Lack of a mitotic apparatus (correct)
Which type of bacteria is characterized by cells that divide in one plane and remain attached as pairs?
Which type of bacteria is characterized by cells that divide in one plane and remain attached as pairs?
- Micrococci
- Streptobacilli
- Tetracocci
- Diplococci (correct)
What distinguishes vibriones from spirilla in terms of bacterial morphology?
What distinguishes vibriones from spirilla in terms of bacterial morphology?
- Vibriones have a rigid wall while spirilla do not
- Both exhibit similar twisting shapes
- Vibriones are coiled forms while spirilla resemble a comma (correct)
- Vibriones lack flagella while spirilla possess it
Which form of bacteria is categorized under higher bacteria due to its resemblance to fungi?
Which form of bacteria is categorized under higher bacteria due to its resemblance to fungi?
What arrangement characterizes streptococci bacteria?
What arrangement characterizes streptococci bacteria?
What is the primary component that gives the bacterial cell wall its strength?
What is the primary component that gives the bacterial cell wall its strength?
What role does the cytoplasmic membrane play in bacterial cells?
What role does the cytoplasmic membrane play in bacterial cells?
How does the presence of a capsule affect bacterial virulence?
How does the presence of a capsule affect bacterial virulence?
Which of the following statements about flagella is true?
Which of the following statements about flagella is true?
What is the general structure of the bacterial cell wall described as?
What is the general structure of the bacterial cell wall described as?
Flashcards
Streptomyces
Streptomyces
A genus of bacteria abundant in soil, producing many antibiotics.
Antibiotics from Streptomyces
Antibiotics from Streptomyces
Streptomycin (from S.griseus) and chloromycetin (from S.venezuelae) are examples.
Bacterial Cell Wall
Bacterial Cell Wall
A rigid, elastic layer surrounding a bacterial cell, made of peptidoglycan and other components. It gives shape and protects the cell.
Mucopeptide (peptidoglycan)
Mucopeptide (peptidoglycan)
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Cytoplasmic Membrane
Cytoplasmic Membrane
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Bacterial Capsule
Bacterial Capsule
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Bacterial Flagella
Bacterial Flagella
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Bacterial Morphology
Bacterial Morphology
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Cocci Bacteria
Cocci Bacteria
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Bacilli Bacteria
Bacilli Bacteria
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Spirilla Bacteria
Spirilla Bacteria
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Micrococci
Micrococci
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Diplococci
Diplococci
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Tetracocci
Tetracocci
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Sarcina
Sarcina
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Streptococci
Streptococci
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Staphylococci
Staphylococci
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Diplobacilli
Diplobacilli
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Streptobacilli
Streptobacilli
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Vibrio
Vibrio
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Spirochaetes
Spirochaetes
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Higher bacteria
Higher bacteria
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Actinomycetes
Actinomycetes
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Study Notes
Bacteria
- Bacteria are small, single-celled microorganisms.
- Some bacteria can form filaments.
- Bacterial cells typically measure between 0.4 and 1.5 micrometers in diameter.
- Bacteria are prokaryotic, lacking a nuclear membrane, mitotic apparatus, mitochondria, and a visible endoplasmic reticulum.
- Bacteria exhibit diverse shapes: cocci (spherical), bacilli (rod-shaped), and spiral forms (vibrios and spirilla).
- Cocci can be further categorized by arrangement (e.g., micrococci, diplococci, streptococci, staphylococci).
- Bacilli can be single, paired (diplobacilli), or in chains (streptobacilli).
- Spirilla and vibrios are spiral-shaped bacteria.
- Higher bacteria (Actinomycetes) resemble fungi with filamentous branching structures.
- Streptomyces are soil-dwelling bacteria that produce antibiotics (e.g., streptomycin, chloromycetin).
- Spirochetes are spiral-shaped bacteria with unique motility.
Bacterial Cell Structure
- Cell wall: A rigid, elastic structure primarily composed of peptidoglycan.
- Cytoplasmic membrane: A thin, flexible membrane controlling substance passage.
- Nucleoid: Contains DNA and is not membrane-bound.
- Ribosomes: Essential for protein synthesis.
- Cytoplasm: The internal environment with various granules, including ribosomes and polysaccharides.
- Capsule/Slime layer: Protective coating surrounding some bacteria.
- Flagella: Used for motility in some species.
- Inclusion granules (e.g., volutin, lipid granules): Non-essential structures that may act as reservoirs of materials.
Bacterial Morphology
- Cocci: Spherical or round-shaped.
- Bacilli: Rod-shaped or cylindrical.
- Spiral forms: Including vibrios (comma-shaped) and spirilla (helical).
Morphology Subdivisions
- Micrococci: Single cells.
- Diplococci: Paired cells.
- Tetracocci: Four cells arranged in a square.
- Sarcina: Eight or more cells arranged in a cuboidal packet.
- Streptococci: Chains of cells.
- Staphylococci: Irregular bunches or clusters of cells.
- Single Bacilli: Not arranged in a pattern.
- Diplobacilli: Paired bacilli.
- Streptobacilli: Bacilli arranged in chains.
Endospores
- Endospores are resistant resting cells produced by some bacteria under unfavorable conditions.
- Endospores allow bacteria to withstand extreme temperatures, drought, and other harsh conditions.
- Endospores facilitate survival and reproduction under unfavorable conditions.
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