|
Home
Cell Structure
and Function
Biomembranes
Photosynthesis
Cell
Respiration
DNA Structure
and Replication
Contacts
|
Biomembranes I:
Membrane Structure and Transport
Concept 4: Passive and Active
Transport
Most biologically important
solutes require protein carriers to cross cell membranes, by a
process of either passive or active transport.
  
Active transport uses energy to move
a solute "uphill" against its gradient, whereas in facilitated
diffusion, a solute moves down its concentration gradient and no
energy input is required.
  |