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General Biology: Inside the Cell and Cell Systems

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  • Prokaryotic cell size compared to eukaryotic cells

    Prokaryotes are about 10 times smaller in diameter and 1000 times smaller in volume than eukaryotic cells.
  • Main components of a prokaryotic cell

    Chromosomes and plasmids (supercoiled), smaller ribosomes, peptidoglycan cell wall, proteins occupying most intracellular space.
  • Functions of flagella and fimbriae in prokaryotes

    Flagella rotate to propel the cell; fimbriae help attachment to surfaces and establish infection.
  • What is Flagellin and its role in immunity?

    Flagellin is a protein in bacterial flagella recognized as a PAMP, triggering immune protective responses.
  • Differences in cell walls between Archaea and bacteria

    Archaea have highly variable cell walls without peptidoglycan; bacteria have peptidoglycan-based cell walls.
  • Key differences between eukaryotic and prokaryotic cells

    Eukaryotic cells are larger, have membrane-bound organelles including nucleus and mitochondria, and motor proteins.
  • Advantages of compartmentalization in eukaryotic cells

    Separation of incompatible reactions and increased efficiency via localized substrates and clustered pathways.
  • Organelles unique to animal cells

    Centrioles and lysosomes occur in animal cells but not in plant cells.
  • Organelles unique to plant cells

    Cell wall, chloroplasts, and large central vacuole are found in plant cells but not animal cells.
  • Structure and function of the nuclear envelope

    Double membrane with pores allowing material passage; nuclear lamina maintains shape.
  • Role of the nucleolus

    Site of ribosomal RNA synthesis inside the nucleus.
  • Nuclear localization sequence (NLS)

    A ~17 amino acid sequence acting as a 'zip code' for proteins to be imported into the nucleus.
  • Difference between free and bound ribosomes

    Free ribosomes synthesize proteins for use inside the cell; bound ribosomes synthesize proteins for secretion or membranes.
  • Functions of rough and smooth endoplasmic reticulum

    Rough ER synthesizes proteins; smooth ER synthesizes and breaks down lipids.
  • Signal hypothesis for protein targeting to rough ER

    ER signal sequence on nascent protein binds SRP, which directs ribosome to ER translocon for protein entry.
  • Golgi apparatus functions

    Processes, sorts, and ships proteins from rough ER; cis face receives, trans face ships out.
  • Endomembrane system pathway

    Rough ER → Golgi apparatus → vesicles → destination organelles or plasma membrane.
  • Role of mannose-6-phosphate in lysosomal targeting

    Acts as a lysosomal 'zip code' recognized by receptors to direct acid hydrolases to lysosomes.
  • Functions of lysosomes

    Recycling center with acid hydrolases that degrade macromolecules at acidic pH (~5.0).
  • Three types of cytoskeletal filaments and their functions

    Microfilaments (movement, transport), intermediate filaments (structure, stability), microtubules (organelle movement, cell division).
  • Role of motor proteins myosin and kinesin

    Myosin moves along actin filaments for cellular movement; kinesin walks along microtubules transporting vesicles.
  • Structure and function of mitochondria

    Double membrane organelle with cristae; produces ATP; contains own DNA and ribosomes.
  • Structure and function of chloroplasts

    Triple membrane organelle with thylakoids stacked into grana; site of photosynthesis; contains own DNA and ribosomes.
  • Peroxisomes and their key enzymes

    Organelles for oxidation/reduction reactions; contain catalase to break down H2O2 and alcohol dehydrogenase.
  • Pulse-chase experiment purpose

    Used to track protein synthesis and movement through rough ER, Golgi, and secretion pathways.