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Prokaryote Lineages definitions Flashcards

Prokaryote Lineages definitions
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  • Proteobacteria
    A diverse clade of gram-negative bacteria, organized into five subgroups (alpha, beta, gamma, delta, epsilon), involved in nitrogen fixation and the origin of mitochondria in eukaryotes.
  • Gram Negative
    Bacteria with a thin peptidoglycan layer beneath an outer lipopolysaccharide membrane, often resistant to antibiotics and stain pink in the Gram stain test.
  • Nitrogen Fixation
    The process by which certain bacteria convert atmospheric nitrogen (N₂) into a form usable by plants and other organisms, typically ammonia (NH₃).
  • Mitochondria
    Organelles in eukaryotic cells that generate ATP through cellular respiration, originally derived from engulfed proteobacteria.
  • Chlamydia
    A group of gram-negative bacteria lacking peptidoglycan in their cell walls, all of which are intracellular parasites, including the species responsible for the STD known by the same name.
  • Peptidoglycan
    A polymer forming a mesh-like layer outside the plasma membrane of most bacteria, providing structural support and shape.
  • Lipopolysaccharide
    A molecule found in the outer membrane of gram-negative bacteria, consisting of a lipid and a polysaccharide, which elicits strong immune responses in animals.
  • Spirochetes
    Gram-negative heterotrophic bacteria with a distinctive corkscrew shape, known for causing Lyme disease and syphilis.
  • Heterotrophs
    Organisms that obtain energy by consuming other organisms or organic matter, as they cannot produce their own food through photosynthesis or chemosynthesis.
  • Cyanobacteria
    Gram-negative photoautotrophs performing oxygenic photosynthesis, crucial for atmospheric oxygen and nitrogen fixation, and ancestors of chloroplasts. Often misnamed blue-green algae.
  • Photoautotrophs
    Organisms that use light energy to convert carbon dioxide and water into organic compounds and oxygen, playing a crucial role in producing atmospheric oxygen.
  • Oxygenic Photosynthesis
    Photosynthesis that produces oxygen as a byproduct, primarily carried out by cyanobacteria, which contributed to the origin of atmospheric oxygen.
  • Stromatolites
    Layered structures formed by cyanobacteria trapping and binding sediment, often considered the oldest known fossils, dating back over a billion years.
  • Actinobacteria
    High GC gram-positive bacteria, often misclassified as fungi due to their branching mycelia. They include Streptomyces, a genus crucial for antibiotic production.
  • Firmicutes
    Low GC gram-positive bacteria, crucial for fermentation (e.g., yogurt, cheese, sour beer) and human health, including gut and vaginal microbiota.