Links
Objectives
- 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.