BIO 121 Lecture Notes - Lecture 7: Endosymbiont, Cellular Respiration, Lysosome
Document Summary
Diffusion is passive- does not require the cell to expend metabolic energy. Active transport requires direct expenditure of energy. Simple diffusion- molecules or ions move directly through the membrane, down their concentration gradient. Facilitated diffusion- specific transport proteins move solutes across a membrane. Ions and hydrophilic substances diffuse across the membrane with the help of a transport protein. Active transport- to move ions or molecules across a membrane against a concentration gradient. Ex: sodium potassium pump uses atp to export three sodium ions and import two potassium ions. Exocytosis- removing large molecules from the cell. Vesicle from interior fuses with the cell membrane and expels contents. Endocytosis- importing macromolecules across the plasma membrane. Receptor mediated endocytosis- a specific signal that receptors recognize specific contents. Eukaryotic cells have internal membranes that compartmentalize their functions. Their genetic instructions are housed in the nucleus and carried out by the ribosome. The endomembrane system regulates proteins traffic and performs metabolic functions.