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Questions and Answers
Which term describes spherical shaped bacteria?
Which term describes spherical shaped bacteria?
What is the characteristic shape of spirochetes?
What is the characteristic shape of spirochetes?
Which arrangement occurs when cocci divide in pairs?
Which arrangement occurs when cocci divide in pairs?
What distinguishes coccobacilli from regular bacilli?
What distinguishes coccobacilli from regular bacilli?
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Which arrangement describes bacilli that form chains?
Which arrangement describes bacilli that form chains?
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What type of bacteria are mycoplasma characterized as?
What type of bacteria are mycoplasma characterized as?
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Which of the following describes the primary structures of bacterial cell components?
Which of the following describes the primary structures of bacterial cell components?
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What is the name for square groups of four cocci cells?
What is the name for square groups of four cocci cells?
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What is the primary function of the bacterial cell wall?
What is the primary function of the bacterial cell wall?
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Which component primarily constitutes the dry weight of a gram-positive bacterial cell wall?
Which component primarily constitutes the dry weight of a gram-positive bacterial cell wall?
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What is the thickness of the gram-negative bacterial cell wall's peptidoglycan layer?
What is the thickness of the gram-negative bacterial cell wall's peptidoglycan layer?
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Which structure is unique to the outer membrane of gram-negative bacteria?
Which structure is unique to the outer membrane of gram-negative bacteria?
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What is one major function of the outer membrane in gram-negative bacteria?
What is one major function of the outer membrane in gram-negative bacteria?
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How does the gram-positive bacterial cell wall differ chemically from that of gram-negative bacteria?
How does the gram-positive bacterial cell wall differ chemically from that of gram-negative bacteria?
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In gram-negative bacteria, what is the function of lipoproteins in the cell wall?
In gram-negative bacteria, what is the function of lipoproteins in the cell wall?
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What is the average thickness of a gram-positive bacterial cell wall?
What is the average thickness of a gram-positive bacterial cell wall?
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What type of acids are found in the cell wall of gram-positive bacteria?
What type of acids are found in the cell wall of gram-positive bacteria?
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What can occur if the cell wall of a bacterium is weakened or ruptured?
What can occur if the cell wall of a bacterium is weakened or ruptured?
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What role do porins play in the outer membrane of gram-negative bacteria?
What role do porins play in the outer membrane of gram-negative bacteria?
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What term describes the process of bacterial cell destruction due to cell wall failure?
What term describes the process of bacterial cell destruction due to cell wall failure?
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What component primarily makes up the cytoplasmic (plasma) membrane of bacteria?
What component primarily makes up the cytoplasmic (plasma) membrane of bacteria?
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Which amino sugars are part of the peptidoglycan structure in bacterial cell walls?
Which amino sugars are part of the peptidoglycan structure in bacterial cell walls?
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What is the primary component of the fungal cell wall that provides structural support?
What is the primary component of the fungal cell wall that provides structural support?
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Which of the following types of spores are produced by mitosis?
Which of the following types of spores are produced by mitosis?
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What type of hyphae are characterized by the absence of cross walls?
What type of hyphae are characterized by the absence of cross walls?
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Which structure serves as the tangled mass of hyphae in molds?
Which structure serves as the tangled mass of hyphae in molds?
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What is the term for the change from yeast form to mycelial form in certain fungi in response to environmental factors?
What is the term for the change from yeast form to mycelial form in certain fungi in response to environmental factors?
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Which of the following components enhances the strength of the fungal cell wall?
Which of the following components enhances the strength of the fungal cell wall?
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Which type of fungal spore is formed by the fusion of cells followed by meiosis?
Which type of fungal spore is formed by the fusion of cells followed by meiosis?
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What are the primary functions of the fungal cell wall?
What are the primary functions of the fungal cell wall?
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Dimorphic fungi can switch forms in response to environmental conditions. What typically triggers this switch?
Dimorphic fungi can switch forms in response to environmental conditions. What typically triggers this switch?
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What type of hyphae feature cross walls known as septa?
What type of hyphae feature cross walls known as septa?
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What is a primary function of the cytoplasmic membrane in bacteria?
What is a primary function of the cytoplasmic membrane in bacteria?
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Which layer is described as being easily washed off and lacks a defined association with the cell?
Which layer is described as being easily washed off and lacks a defined association with the cell?
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What type of proteins primarily compose bacterial flagella?
What type of proteins primarily compose bacterial flagella?
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What is the role of sex pili in bacteria?
What is the role of sex pili in bacteria?
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Which part of the flagellum serves as the connection between the filament and the basal body?
Which part of the flagellum serves as the connection between the filament and the basal body?
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What composition is common for capsules and slime layers in bacteria?
What composition is common for capsules and slime layers in bacteria?
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What characteristic of capsules serves as a virulence factor in bacteria?
What characteristic of capsules serves as a virulence factor in bacteria?
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What type of cellular structure is primarily found in the cytoplasm of bacteria?
What type of cellular structure is primarily found in the cytoplasm of bacteria?
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What process do ordinary pili primarily assist with in bacteria?
What process do ordinary pili primarily assist with in bacteria?
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Which rings are present in the basal body of flagella in gram-negative bacteria?
Which rings are present in the basal body of flagella in gram-negative bacteria?
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What role does the capsule play in the identification of bacteria?
What role does the capsule play in the identification of bacteria?
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Which of the following is a function of the cytoplasmic membrane?
Which of the following is a function of the cytoplasmic membrane?
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What is a major difference between fimbriae and flagella?
What is a major difference between fimbriae and flagella?
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What is the primary function of ribosomes in bacteria?
What is the primary function of ribosomes in bacteria?
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Which characteristic distinguishes eukaryotic ribosomes from bacterial ribosomes?
Which characteristic distinguishes eukaryotic ribosomes from bacterial ribosomes?
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What are mesosomes believed to be involved in during bacterial cell division?
What are mesosomes believed to be involved in during bacterial cell division?
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What is the function of volutin granules in bacteria?
What is the function of volutin granules in bacteria?
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Which structure in bacterial cells is analogous to mitochondria in eukaryotic cells?
Which structure in bacterial cells is analogous to mitochondria in eukaryotic cells?
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What is a defining feature of the bacterial chromosome?
What is a defining feature of the bacterial chromosome?
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How do yeasts primarily reproduce?
How do yeasts primarily reproduce?
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Which of the following describes dimorphic fungi?
Which of the following describes dimorphic fungi?
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What term describes the tangled mass of hyphae in molds?
What term describes the tangled mass of hyphae in molds?
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Which type of fungi primarily consists of single, unicellular organisms?
Which type of fungi primarily consists of single, unicellular organisms?
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The study of fungi is referred to as what?
The study of fungi is referred to as what?
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What structure in fungi is responsible for nutrient absorption?
What structure in fungi is responsible for nutrient absorption?
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Which of the following is NOT a characteristic of fungi?
Which of the following is NOT a characteristic of fungi?
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What are the filamentous shapes in molds called?
What are the filamentous shapes in molds called?
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Study Notes
Bacterial Morphology and Structure
- Bacteria are prokaryotic microorganisms, small in size (0.2µm-1.5µm diameter, 3µm-5µm length)
- Morphology describes shape, size, and arrangement
- Bacterial shapes include:
- Cocci: spherical (e.g., Staphylococcus, Streptococcus)
- Bacilli: rod-shaped (e.g., coccobacilli)
- Vibrios: curved or comma-shaped
- Spirilla: rigid spiral
- Spirochetes: flexuous spiral (e.g., Campylobacter)
- Mycoplasma (pleomorphic): cell wall-deficient, irregular shapes
Bacterial Arrangement
- Cocci arrangements vary based on division planes:
- Diplococci: pairs
- Chains: repeated divisions in one plane
- Clusters: divisions in random planes
- Tetrads: groups of four
- Packets: groups of eight
- Bacilli arrangements are limited, often in chains (streptobacilli)
Bacterial Cell Envelope
- Outer layer consisting of:
- Cell wall: rigid, permeable layer (10-25nm thick)
- Gives shape and rigidity, supports cytoplasmic membrane, maintains shape, involved in division and interactions with other cells or mammalian cells. Provides receptors for some bacterial viruses.
- Composed of peptidoglycan (mucopeptide/murein): alternating N-acetyl glucosamine and N-acetyl muramic acid linked by peptide bonds. Different cross-bridges and tetrapeptide chains vary by species.
- Cytoplasmic (plasma) membrane: thin (5-10nm), elastic, lies beneath cell wall, controls metabolite flow, houses enzymes for synthesis, energy generation (ATP), and motility, mediates chromosomal segregation
- Cell wall: rigid, permeable layer (10-25nm thick)
Gram-Positive vs. Gram-Negative Cell Walls
- Gram-positive walls: simpler, thicker peptidoglycan layer (50-90% dry wall weight), also contain teichoic acids (glycerol/ribitol + phosphate)
- Gram-negative walls: more complex, thinner peptidoglycan layer (5-10% dry wall weight), contains lipoprotein, outer membrane, and lipopolysaccharide (LPS). LPS is a large complex molecule (lipid A, core polysaccharide, O polysaccharide).
- Outer membrane acts as a protective barrier (prevents toxic substance entry) through porins (transmembrane proteins)
Bacterial Appendages
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Capsule/Slime Layer: extracellular polymer, protects against phagocytosis, cell wall attack, used in bacterial identification and typing.
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Flagella: long, helical filaments (flagellin protein), allow motility, with filament, hook, and basal body components. Basal body has different ring structures depending on type (gram + or gram -)
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Fimbriae/Pili: short, hair-like appendages, adhesion, and transfer of genetic material (sex pili). Sex pili facilitate conjugation, the transfer of genetic material from one bacteria to another.
Bacterial Cell Interior
- Cytoplasm: viscous solution with organic/inorganic solutes, ribosomes, and no internal structures seen in eukaryotes.
- Ribosomes: 70S (30S + 50S), site of protein synthesis, smaller than eukaryotic ribosomes (80S). Components include mRNA, rRNA, tRNA.
- Mesosomes (chondroids): invaginations of plasma membrane, involved in DNA compartmenting, site of some respiratory enzymes in bacteria analogous to mitochondria in eukaryotes.
- Intracellular Inclusions: storage bodies (volutin/polyphosphate, lipid, glycogen, starch).
- Bacterial Nucleus: single circular DNA molecule, haploid, replicates through simple fission, not membrane-bound.
Fungi
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Eukaryotic, spore-bearing, lacking chlorophyll, absorptive nutrition.
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Mycology: study of fungi.
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Growth forms (Yeasts and Molds)
- Yeasts: unicellular, asexual reproduction (budding/fission)
- Molds: filamentous, hyphae form a mycelium, septate/non-septate
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Fungal cell wall is a complex structure providing support, protection, and maintaining cellular shape. It's composed of chitin and other polysaccharides.
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Types of fungal spores:
- Sexual: oospores, ascospores, zygospores, basidiospores formed during meiosis.
- Asexual: vegetative (blastospores, arthrospores, chlamydospores) and aerial (conidia, microconidia, macroconidia), sporangiospores.
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Dimorphic Fungi: two forms (yeast or mold) depending on environmental conditions (eg: temperature); change from Y (yeast) to M (mold) is called YM shift.
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Description
Test your knowledge on the morphology and structure of bacteria, including their shapes, arrangements, and cell envelopes. This quiz covers essential characteristics of different bacterial types and their classification. Perfect for microbiology enthusiasts and students!
