B: how things move in cells

• mRNAs and tRNAs are transported out of the nucleas
• nucleotides enter the nucleus through diffusion
• NLS are attached to nuclear imports
• importin proteins carry proteins into the nucleus
• NES are attached to nuclear exports
• exportin proteins attach to the NES in order to transport the cargo out of the nucleus
• RAN protein allows for the importins and exportins to move in the correct direction
• RAN-GTP is the active RAN complex
• RAN-GDP is the inactive RAN complex
• RAN-GDP is found in the cytosol
• RAN-GTP is found in the nucleus
• ER enzymes synthesize membrane lipids for the whole cell
• lipids are delivered to the ER and the nucleus through lateral diffusion
• lipids are delivered to the endomembrane system through transport vesicles
• lipids are delivered to the mitochondria and the peroxisomes through phospholipid exchange proteins
• proteins are synthesized by:

  1. free ribosomes
  2. rough ER ribosomes
• cytosol proteins are made by free ribosomes
• proteins are these organelles are made by free ribosomes and then imported

  1. mitochondria
  2. peroxisomes
  3. nucleus
• export proteins are made in the ER and require an ER signal
• export proteins travel by vesicle
• membrane proteins are made in the ER and require an ER-signal and a trans membrane domain
• nuclear envelope and ER proteins are made in the ER then delivered through lateral diffusion
• endomembrane proteins are made by ER ribosomes and then transported by vesicles
• consecutive exocytosis is the default pathway
• regulated exocytosis requires a signal to allow for export
• M6P receptors bring the enzymes to the lysosomes
• when the pH drops, endosomes become lysosomes