Cell Structure and Functions, Animation

Key Takeaways

• The plasma membrane is a phospholipid bilayer with embedded proteins that controls substance traffic, enables cell communication, and maintains structural integrity.
• Membrane proteins serve diverse roles including receptors, channels, adhesion molecules, enzymes, and surface antigens that determine cell identity.
• The nucleus houses DNA for replication and transcription, with a double membrane containing nuclear pores for controlled material exchange.
• Ribosomes on rough ER synthesize secretory and transmembrane proteins, while smooth ER produces lipids and stores calcium for cellular processes.
• The Golgi apparatus modifies proteins and lipids via sequential enzyme steps in its cisternae, then packages them into vesicles for targeted delivery.
• Lysosomes contain acid-activated hydrolases that break down macromolecules for recycling, playing key roles in immune defense against pathogens.
• Mitochondria generate energy through cellular respiration, with the citric acid cycle in the matrix and oxidative phosphorylation on cristae folds.
• The cytoskeleton's three filament types—microfilaments, intermediate filaments, and microtubules—provide structure, enable movement, and guide cell division.