3: Organization at the Cellular Level Last updated Save as PDF Page ID 7131 3.1: Introduction to the Study of Cells 3.1A: Cells as the Basic Unit of Life 3.2: Cell Membranes and the Fluid Mosaic Model 3.2A: Components of Plasma Membranes 3.2B: Fluid Mosaic Model 3.2C: Membrane Fluidity 3.3: Transport Across Membranes 3.3A: Diffusion 3.3B: Osmosis 3.3C: Tonicity 3.3D: Facilitated transport 3.3E: The Role of Passive Transport 3.3F: Primary Active Transport 3.3G: Electrochemical Gradient 3.3H: Secondary Active Transport 3.3I: Endocytosis 3.4: Cell Signaling 3.4A: Types of Receptors 3.5: The Nucleus and Ribosomes 3.5A: The Nucleus and Ribosomes 3.5B: Characteristics of Eukaryotic Cells 3.6: Organelles 3.6A: The Plasma Membrane and the Cytoplasm 3.6B: The Endoplasmic Reticulum 3.6C: The Golgi Apparatus 3.6D: Lysosomes 3.6E: Peroxisomes 3.6F: Mitochondria 3.7: The Cytoskeleton 3.7A: Intermediate Filaments and Microtubules 3.7B: Microfilaments 3.8: External Cellular Components 3.8A: Extracellular Matrix of Animal Cells 3.8B: Intercellular Junctions