Final answer:
Aquaporins facilitate efficient water movement across cell membranes through facilitated diffusion, and their discovery earned Peter Agre a Nobel Prize. They are gated and can respond to environmental stresses like flooding or drought, by adjusting water permeability to maintain homeostasis.
Step-by-step explanation:
The movement of water across cell membranes is primarily facilitated by the presence of aquaporins, which are specialized channels for water transport. Water can also cross the membrane incidentally when ions flow through their channel proteins, or by slipping between the lipid tails of the membrane itself. However, facilitated diffusion through aquaporins is the most efficient way for water to cross membranes quickly. Aquaporins are essential for maintaining proper cellular function by allowing cells to adjust to varying concentrations of solutes in their environments. The discovery of aquaporins was so significant that it led to a Nobel Prize in Chemistry for Peter Agre in 2003.
Advantages of Aquaporin Gating
Aquaporins are gated and can be regulated by the pH within the cell. This feedback mechanism allows cells to respond to environmental stress situations, such as flooding or drought, by adjusting water permeability to maintain homeostasis and protect cellular integrity.