Cell structure and organelles

Nucleus

Nuclear pore complexes

  • Composed of nucleoporins
  • ↑ transcriptional activity = ↑ nuclear pore complexes
  • Typically = 3000-4000
  • DNA synthesis requires 106 histone molecules importing from cytosol every 3 minutes
  • Each pore complex has ≥ 1 aqueous channels allowing passive diffusion of water soluble molecules
  • Small molecules (≤ 5000 daltons) diffuse rapidly
  • 17000 daltons takes 2 minutes
  • Impermeable to ≥ 60000 daltons
  • Receptor proteins enable specific large molecules to cross

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