Principles Module 17

Principles Module 18

Overview slides


  • Describe the structure of cell membranes
  • Explain how membranes function in exchange

Key points

  • membranes are selectively permeable and part of the sensory system
  • made of phospholipids, amphipathic, form bilayer
    • allows nonpolar molecules to diffuse straight across
  • have proteins either attached (peripheral) or spanning (integral)
    • some act in transport, others in cell identity, others in signaling
  • fluidity depends on composition of membrane
    • varied sterols or degree of saturation
  • transport across membrane depends on concentration of solute = diffusion
    • when across membrane = osmosis
    • osmoregulation
  • channel proteins can facillitate diffusion of a specific molecule in a specific direction
  • transport may be passive (not require energy) or active
  • membrane potential provides the driving force for much transport

In-class activities

Membrane Transport Enactment

Working in groups (or groups of groups) and using your selves as carriers, pumps, and various solutes, enact the transport dynamics of both the sodium/potassium pump and the sucrose co-transporter. Make sure you understand the driving force for transport in both of these examples.