Membrane Transport Mechanisms
Cells have sophisticated ways to move materials across membranes! Phagocytosis allows cells to engulf large particles, while different forms of transport move smaller molecules. Understanding these mechanisms helps explain how cells maintain their internal environment.
When different cells encounter the same environment, they may respond differently. If a red blood cell and a plant cell were placed in seawater (a hypertonic solution), the red blood cell would shrink as water leaves through osmosis, while the plant cell would lose water and its plasma membrane would pull away from the cell wall.
Not all molecules can pass through membranes easily. Glucose, which diffuses slowly through artificial phospholipid bilayers, can be rapidly transported into intestinal cells through facilitated diffusion using specific carrier proteins. Moving substances against their concentration gradient, like pumping potassium into a cell, requires active transport and an energy source such as ATP.
⚡ Your cells use energy currency (ATP) to power active transport! This is how cells maintain concentration differences that are essential for nerve impulses, nutrient absorption, and many other vital functions.