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Prokaryotes: Structure, Function, and Diversity

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이 집합의 용어 (24)

  • What are the two domains of prokaryotes?
    Bacteria and Archaea are the two domains of prokaryotes.
  • What are the three common shapes of prokaryotic cells?
    The three common shapes are cocci (spherical), bacilli (rod-shaped), and spirals.
  • What is the main component of most bacterial cell walls?
    Most bacterial cell walls contain peptidoglycan, a network of sugar polymers cross-linked by polypeptides.
  • How do Gram-positive and Gram-negative bacteria differ in cell wall structure?
    Gram-positive bacteria have thick peptidoglycan layers; Gram-negative bacteria have thinner peptidoglycan and an outer membrane with lipopolysaccharides.
  • What is the function of a bacterial capsule?
    The capsule is a sticky outer layer that helps bacteria adhere to surfaces and can protect pathogenic bacteria from the host immune system.
  • What is an endospore in prokaryotes?
    An endospore is a metabolically inactive, resistant structure that can survive harsh conditions for centuries.
  • What are fimbriae and pili in prokaryotes?
    Fimbriae are hairlike appendages for attachment; pili (sex pili) are longer and enable DNA exchange between cells.
  • What is taxis in prokaryotes?
    Taxis is the ability to move toward or away from a stimulus, such as chemotaxis toward or away from chemicals.
  • How do prokaryotic flagella differ from eukaryotic flagella?
    Prokaryotic flagella differ in structure, propulsion mechanism, and molecular composition from eukaryotic flagella.
  • Where is the prokaryotic chromosome located?
    The chromosome is circular and located in the nucleoid region, which lacks a surrounding membrane.
  • What are plasmids in prokaryotes?
    Plasmids are smaller, independently replicating rings of DNA separate from the main chromosome.
  • How do prokaryotes reproduce?
    Prokaryotes reproduce asexually by binary fission, often dividing every 1–3 hours under optimal conditions.
  • What three factors contribute to genetic diversity in prokaryotes?
    Rapid reproduction, mutation, and genetic recombination contribute to prokaryotic genetic diversity.
  • What is horizontal gene transfer?
    Horizontal gene transfer is the movement of genes between individuals of different species.
  • Name three mechanisms of genetic recombination in prokaryotes.
    Transformation (uptake of foreign DNA), transduction (gene transfer by phages), and conjugation (DNA transfer via pili).
  • What is the F factor in bacterial conjugation?
    The F factor is a DNA segment required for pilus production and DNA transfer during conjugation.
  • What are R plasmids?
    R plasmids carry genes for antibiotic resistance and can spread resistance between bacteria.
  • What are the four major nutritional modes of prokaryotes?
    Photoautotroph, chemoautotroph, photoheterotroph, and chemoheterotroph, based on energy and carbon sources.
  • What is nitrogen fixation?
    Nitrogen fixation is the conversion of atmospheric nitrogen (N2) to ammonia (NH3) by some prokaryotes.
  • What is a biofilm?
    A biofilm is a surface-coating colony of prokaryotes that cooperate metabolically.
  • What roles do prokaryotes play in the biosphere?
    Prokaryotes recycle chemical elements, decompose organic matter, and increase nutrient availability for plants.
  • What is symbiosis?
    Symbiosis is a close ecological relationship between two species, such as mutualism, commensalism, or parasitism.
  • How do pathogenic bacteria cause disease?
    Pathogens release exotoxins (secreted) or endotoxins (released when bacteria die) that cause disease symptoms.
  • How are prokaryotes used in biotechnology?
    Prokaryotes are used in gene cloning, CRISPR gene editing, bioplastics production, ethanol production, and bioremediation.