Transport

Most to Least Permeable

• hydrophobic (nonpolar)
• small, uncharged, polar molecules
• large, uncharged, polar molecules
• ions

large consumption

• pinocytosis: cell drinking
• phagocytosis: cell eating

Facilitated Diffusion Limitations

• saturation (limited number of carriers)
• stereospecificity (orientation matters)
• competition (similar solutes compete for binding sites)

Integral Proteins

• channels: basically just tunnels
  • non-gated: always open
  • gated: can close
• carriers: require something to bind to it and then changes shape

Primary Active Transport

• ATP is directly coupled to solute movement
• Na+/K+ pump
  • 3 Na+ out and 2 K+ in
• Ca2+ pump
  • out of cell
  • pump into SR and ER
• ATPase
  • turns ATP into ADP

Secondary Active Transport

• ATP is indirectly coupled to solute transport
• co-transport (symport): move in same direction
• counter-transport (antiport): move in opposite directions

Osmolarity & Tonicity

• osmolarity: number of dissolved particles/volume
  • colligative property: dependent on total number of particles. doesn’t depend on size or charge
• tonicity: dependent on concentration of impermeant solute

normal saline: 0.9% NaCl