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General Biology: Cell Structure and Function

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Termini in questo insieme (20)

  • Key differences between prokaryotic and eukaryotic cells
    Prokaryotic cells have a stiff cell wall, single circular chromosome in nucleoid, plasmids, and external appendages like fimbriae and flagella. Eukaryotic cells have a nucleus, membrane-bound organelles, and complex cytoskeleton.
  • Function of fimbriae vs flagella in prokaryotes
    Fimbriae are short, sticky appendages used for attachment. Flagella are long, hair-like structures used for movement.
  • Organelles containing their own DNA in eukaryotic cells
    Mitochondria and chloroplasts contain their own DNA, supporting the endosymbiosis theory.
  • Role of centrosomes and centrioles in animal cells
    Centrosomes are microtubule organizing centers containing two bundles of microtubules called centrioles, important for cell division. Plants lack centrioles but have microtubules.
  • Function of lysosomes
    Lysosomes act as recycling centers containing acid hydrolases that digest macromolecules and damaged organelles at acidic pH (~5.0).
  • Differences in plant and animal cells
    Plant cells have a cell wall and chloroplasts, while animal cells have centrioles and lysosomes but lack cell walls and chloroplasts.
  • Endosymbiosis theory
    Proposes mitochondria and chloroplasts evolved from free-living bacteria engulfed by ancestral eukaryotes, leading to a mutually beneficial relationship.
  • Nuclear envelope structure and function
    The nuclear envelope has two membranes with nuclear pores that regulate import/export of proteins and RNA between nucleus and cytoplasm.
  • Nuclear localization signal (NLS)
    A 17 amino acid sequence that acts as a molecular zip code directing proteins from cytosol into the nucleus.
  • Components of the endomembrane system
    Includes nucleus, rough and smooth ER, Golgi apparatus, vesicles, lysosomes, and plasma membrane; involved in synthesis, processing, and transport of proteins and lipids.
  • ER signal sequence and protein targeting
    A 20 amino acid sequence on growing polypeptides that binds signal recognition particle (SRP) directing ribosomes to the ER membrane for protein translocation.
  • Role of the translocon in the ER
    A channel in the ER membrane through which growing proteins enter the ER lumen during synthesis.
  • Pathway of protein secretion
    Proteins synthesized in the rough ER are processed in the Golgi apparatus, packaged into vesicles, and secreted via exocytosis at the plasma membrane.
  • Difference between acid hydrolase targeting and secretion
    Acid hydrolases are targeted to lysosomes to digest waste and are not secreted outside the cell, unlike some secreted proteins.
  • Exocytosis process
    Release of intracellular molecules contained in membrane-bound vesicles by fusion of vesicles with the plasma membrane.
  • Function of insulin protein hormone
    Lowers blood glucose levels; synthesized from mRNA in ER, processed in Golgi, and secreted by exocytosis.
  • Role of protein hormone receptors
    Bind protein hormones on the cell surface to trigger cellular responses; receptors are transported to the plasma membrane but not secreted.
  • Cytoskeleton filament types and functions
    Actin filaments maintain cell shape and enable movement; intermediate filaments provide tensile strength; microtubules resist compression, assist cell division, and intracellular transport.
  • Actin and myosin interaction
    Drive cell movement, cytoplasmic streaming, and cytokinesis in animal cells.
  • Size comparison of prokaryotic and eukaryotic cells
    Prokaryotic cells are about 10 times smaller in diameter and 1000 times smaller in volume than eukaryotic cells.