Essential Idea:
Membranes control the composition of cells
by active and passive transport
Understandings:
- Particles move across membranes by simple diffusion, facilitated diffusion, osmosis and active transport
- The fluidity of membranes allows materials to be taken into cells by endocytosis or released by exocytosis
- Vesicles move materials within cells
Applications:
- Structure and function of sodium-potassium pumps for active transport and potassium channels for facilitated diffusion in axons
- Tissues or organs to be used in medical procedures must be bathed in a solution with the same osmolarity as the cytoplasm to prevent osmosis
Skills:
- Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions