Cell Membrane Transport
Ever wonder how stuff gets in and out of your cells? Cell membranes are selectively permeable, allowing only certain substances like water, small fats, oxygen, and CO₂ to pass through naturally.
Diffusion is a passive transport process that doesn't require energy. Molecules simply move from areas of higher concentration to lower concentration. The diffusion rate depends on three key factors: smaller molecules move faster, higher concentration differences create faster movement, and higher temperatures speed up the entire process.
Osmosis is a special type of diffusion specifically for water molecules. Water moves across a semi-permeable membrane from areas with fewer dissolved substances to areas with more dissolved substances.
Quick Tip: Think of osmosis like a crowd at a concert - water molecules "rush" toward the area where they're needed most (where there are more dissolved substances).
Cell solutions come in three important types based on solute concentration. Isotonic solutions have the same concentration as cell cytoplasm, resulting in no net water movement and maintaining normal cell shape. Hypertonic solutions contain more solutes than the cytoplasm, causing water to flow out of the cell and making it shrink. The cell membrane can also transport materials through facilitated diffusion and active transport, which require specialized proteins.
