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Prokaryote Cell Structures exam Flashcards

Prokaryote Cell Structures exam
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  • Prokaryotes
    Organisms, including bacteria and archaea, that lack a nucleus and membrane-bound organelles.
  • Nucleoid
    The region in a prokaryotic cell where the DNA is concentrated.
  • What is the main structural difference between gram-positive and gram-negative bacteria?
    Gram-positive bacteria have a thick peptidoglycan layer, while gram-negative bacteria have a thin peptidoglycan layer and an outer membrane of lipopolysaccharides.
  • Plasmids
    Small, extra-chromosomal DNA molecules found in prokaryotes.
  • Peptidoglycan
    A polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of most bacteria, providing structural support.
  • What is the function of the cell wall in prokaryotes?
    To provide shape and protect the cell from osmotic pressure.
  • Gram Stain
    A staining technique used to classify bacteria based on the structure of their cell walls.
  • What are fimbriae?
    Hair-like appendages that allow bacteria to adhere to surfaces.
  • Capsule (or slime layer)
    A polysaccharide layer that surrounds some prokaryotic cells, providing protection and aiding in adherence to surfaces.
  • Endospores
    Dormant, tough, and non-reproductive structures produced by some bacteria to survive extreme conditions.
  • What is the role of flagella in prokaryotes?
    Flagella are used for locomotion and sometimes sensation.
  • Pilus (or sex pilus)
    A tube-like appendage used by bacteria to transfer DNA during conjugation.
  • Archaea
    A domain of prokaryotes that are biochemically distinct from bacteria and often found in extreme environments.
  • What is a key biochemical difference between archaea and bacteria?
    Archaea lack peptidoglycan in their cell walls and have unique membrane compositions.
  • Extremophiles
    Organisms, often archaea, that thrive in extreme environmental conditions.
  • Methanogens
    A type of archaea that produces methane as a byproduct of their metabolism.
  • What is the significance of prokaryotes in Earth's biomass?
    Prokaryotes make up 60% of Earth's biomass and are essential to ecological and evolutionary dynamics.
  • Conjugation
    A process by which one bacterium transfers genetic material to another through direct contact.
  • What is the function of the periplasmic space in gram-negative bacteria?
    It is a gap between the outer membrane and the plasma membrane, important for various cellular processes.
  • Thermophiles
    Archaea that thrive in extremely hot environments, such as hot springs and hydrothermal vents.
  • Halophiles
    Archaea that thrive in highly saline environments, such as the Dead Sea.
  • What is the structure of prokaryotic DNA?
    Prokaryotic DNA is typically circular and double-stranded.
  • Lipopolysaccharides
    Molecules consisting of lipids and polysaccharides that form the outer membrane of gram-negative bacteria.
  • What is the role of the capsule in prokaryotic cells?
    The capsule provides an additional protective layer and helps in adherence to surfaces.
  • Gene Transfer
    The movement of genetic material between organisms, which can occur through processes like conjugation in prokaryotes.
  • What are the main components of peptidoglycan?
    Peptidoglycan is composed of sugar chains cross-linked by small peptides.
  • What is the function of endospores?
    Endospores allow bacteria to survive in harsh conditions by entering a dormant state.
  • What is the significance of the Gram stain technique?
    It helps classify bacteria based on their cell wall structure, distinguishing between gram-positive and gram-negative bacteria.