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Exam 1

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Termini in questo insieme (20)

  • What are the three domains of the microbial world?

    The three domains are Bacteria, Archaea, and Eukarya.

  • What distinguishes prokaryotic cells from eukaryotic cells?

    Prokaryotes lack a nucleus and membrane-bound organelles, are smaller (~1 µm), and reproduce asexually. Eukaryotes have a nucleus, membrane-bound organelles, and are larger (10–100 µm).

  • What are glycocalyces and their types in bacteria?

    Glycocalyces are gelatinous, sticky substances outside the cell composed of polysaccharides or polypeptides. Types: Capsule (organized, firmly attached) and Slime layer (loose, water-soluble).

  • What is the function of bacterial flagella?

    Flagella provide motility by rotating to propel bacteria through their environment, driven by proton motive force. Rotation can be counterclockwise (runs) or clockwise (tumbles).

  • How do spirochetes move differently from other bacteria?

    Spirochetes have axial filaments (endoflagella) wrapped around the cell that rotate to produce a corkscrew motion, unlike external flagella.

  • What are fimbriae and pili in bacteria?

    Fimbriae are short, proteinaceous projections for attachment and biofilm formation. Pili are longer tubules used for DNA transfer during conjugation.

  • What is peptidoglycan and its role in bacterial cell walls?

    Peptidoglycan is a mesh-like polymer of alternating sugars (NAG and NAM) linked by tetrapeptides, providing structural support and shape to bacterial cell walls.

  • How do Gram-positive and Gram-negative bacterial cell walls differ?

    Gram-positive walls have a thick peptidoglycan layer with teichoic acids and stain purple. Gram-negative walls have a thin peptidoglycan layer and an outer lipid membrane containing lipopolysaccharide (LPS), staining pink.

  • What is the significance of Lipid A in Gram-negative bacteria?

    Lipid A is part of LPS and can trigger fever, inflammation, shock, and blood clotting during infections.

  • Describe the cytoplasmic membrane structure and function in bacteria.

    The cytoplasmic membrane is a phospholipid bilayer with proteins, selectively permeable, involved in energy storage, transport, and maintaining gradients.

  • What are the main types of transport across bacterial cytoplasmic membranes?

    Passive transport (diffusion, facilitated diffusion, osmosis) requires no ATP. Active transport (active transport, group translocation) requires ATP to move substances against gradients.

  • What are bacterial endospores and their function?

    Endospores are highly resistant dormant structures formed under stress to protect bacteria from heat, radiation, and chemicals.

  • What are the main components of bacterial cytoplasm?

    Cytoplasm contains cytosol (water, ions, nutrients), DNA in the nucleoid, ribosomes (70S), and inclusions for storage.

  • How do archaea differ from bacteria?

    Archaea have unique membrane lipids (ether linkages), lack peptidoglycan in cell walls, have different ribosomal proteins, and some have hami for attachment.

  • What are key differences between prokaryotic and eukaryotic flagella?

    Prokaryotic flagella rotate and are made of flagellin. Eukaryotic flagella undulate rhythmically, are made of tubulin microtubules arranged in a 9+2 pattern, and are covered by the cytoplasmic membrane.

  • What unique active transport processes occur in eukaryotic cells?

    Eukaryotic cells perform endocytosis (phagocytosis and pinocytosis) and exocytosis to move large substances across membranes.

  • Name major membrane-bound organelles in eukaryotic cells and their functions.

    Nucleus (DNA storage), endoplasmic reticulum (protein/lipid transport), Golgi body (processing and packaging), lysosomes (digestion), peroxisomes (detoxification), mitochondria (ATP production), chloroplasts (photosynthesis).

  • What is the endosymbiotic theory?

    The theory that mitochondria and chloroplasts evolved from ancient prokaryotes engulfed by ancestral eukaryotic cells.

  • How do eukaryotic ribosomes differ from prokaryotic ribosomes?

    Eukaryotic ribosomes are larger (80S) composed of 60S and 40S subunits, while prokaryotic ribosomes are smaller (70S) with 50S and 30S subunits.

  • What are the main groups of eukaryotic microbes?

    Algae (photosynthetic), protozoa (motile, heterotrophic), fungi (absorptive heterotrophs), and helminths (multicellular parasites).