BIO E121 Lecture Notes - Lecture 8: Membrane Protein, Facilitated Diffusion, Exocytosis
Document Summary
Selectively permeable regulates movements of substances in and out of cell. Define concentration gradient and use illustrations to help explain the definition. More of a substance on one side of plasma membrane if concentrations are equal then no cg exists. Facilitated diffusion: movement of substances from higher concentration regions to lower concentration regions with the aid of a membrane protein. Osmosis: movement of water across a selectively permeable membrane from a higher region of water concentration to a lower region of water concentration. Water molecules move to dilute the solution. This membrane is not permeable to solute only water. Active transport: movement from a lower region to higher concentration with the aid of a career protein and energy, typically atp. Exocytosis: large molecules are enclosed in membrane-bound vesicles, which travels to plasma membranes, where they are released outside. Endocytosis: materials are engulfed by the plasma membrane and drawn into the cell in a vesicle.
