Introduction to Cell Biology

1. Cellular Structures
   1. Plasma Membrane
      1. Structure and Composition
         1. Phospholipid bilayer
         2. Embedded proteins
         3. Cholesterol
         4. Glycolipids and glycoproteins
      2. Functions
         1. Selective Permeability
            1. Passive transport
               1. Diffusion
               2. Osmosis
               3. Facilitated diffusion
            2. Active transport
               1. Pumps (e.g., sodium-potassium pump)
               2. Endocytosis and exocytosis
         2. Communication
            1. Receptor proteins
            2. Signal transduction
         3. Cell recognition and adhesion
            1. Cell junctions
            2. Role of carbohydrates
   2. Cytoplasm
      1. Components
         1. Cytosol
            1. Composition (water, ions, dissolved molecules)
            2. Functions as a cellular matrix
         2. Organelles (see detailed list below)
         3. Cytoskeleton
            1. Microfilaments (actin filaments)
               1. Structure and function
               2. Role in cellular movement
            2. Intermediate filaments
               1. Structural support
            3. Microtubules
               1. Role in shape maintenance
               2. Intracellular transport
               3. Importance in cell division
   3. Nucleus
      1. Structure
         1. Nuclear envelope
            1. Double membrane
            2. Nuclear pores
         2. Chromatin
            1. Euchromatin and heterochromatin
         3. Nucleolus
            1. Role in ribosome assembly
      2. Functions
         1. DNA Storage
            1. Chromosome organization
         2. RNA Synthesis
            1. Transcription process
            2. mRNA processing and transport
   4. Organelles
      1. Mitochondria
         1. Structure
            1. Double membrane
            2. Matrix and cristae
         2. Role in Energy Production
            1. ATP synthesis
            2. Role in cellular respiration
      2. Endoplasmic Reticulum (ER)
         1. Rough ER
            1. Structure
               1. Ribosome attachment
               2. Membrane-bound network
            2. Functions in Protein Synthesis
               1. Synthesis of membrane and secretory proteins
               2. Initial protein folding and modification
         2. Smooth ER
            1. Structure
               1. Tubular network
            2. Functions in Lipid Synthesis
               1. Lipid and steroid hormone production
               2. Involved in detoxification processes
      3. Golgi Apparatus
         1. Structure
            1. Stack of membrane-bound cisternae
         2. Function in Protein Modification and Sorting
            1. Glycosylation and phosphorylation
            2. Trafficking proteins to destinations
            3. Vesicle formation
      4. Lysosomes
         1. Structure
            1. Membrane-bound organelle containing hydrolytic enzymes
         2. Role in Digestion and Recycling
            1. Breakdown of macromolecules
            2. Autophagy and cellular waste management
      5. Ribosomes
         1. Structure
            1. Composed of rRNA and proteins
            2. Two subunits (large and small)
         2. Role in Protein Synthesis
            1. Translation of mRNA into polypeptide chains
            2. Localization on rough ER or free in cytoplasm
      6. Chloroplasts (in plant cells)
         1. Structure
            1. Double membrane
            2. Thylakoids and stroma
         2. Role in Photosynthesis
            1. Light-dependent reactions
            2. Calvin cycle (light-independent reactions)
   5. Other Important Structures
      1. Cell Wall (in plant cells and some other organisms)
         1. Composition
            1. Cellulose in plants
            2. Chitin in fungi
            3. Peptidoglycan in bacteria
         2. Functions
            1. Provides support and protection
            2. Maintains cell shape
         3. Interaction with plasma membrane
      2. Vacuoles
         1. Structure and variability (large central vacuole in plant cells)
         2. Functions in storage and homeostasis
            1. Storage of nutrients and waste products
            2. Role in maintaining turgor pressure in plant cells