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Cell Theory

• The cell is the smallest unit of life.
• Organismal functions depend on cell functions.
• Biochemical activities are determined by subcellular structures.
• Continuity of life is cell-based.

Cell Structure

• Non-membrane-bound organelles: Ribosomes, Centrosome, Cytoskeleton.
• Membrane-bound organelles: Rough ER, Smooth ER, Golgi apparatus, Lysosome, Nucleus, Mitochondrion.
• Plasma membrane modifications: Microvilli, Cilia, Flagellum.

Membrane Transport

Passive Transport

• No cellular energy required.
• Types: Diffusion (simple and facilitated), Osmosis.

Active Transport

• Requires energy (ATP).
• Types: Primary (direct use of ATP), Secondary (indirect use).
• Processes: Vesicular transport, Active and Passive transport mechanisms in different cells.

Endocytosis and Exocytosis

• Endocytosis: Phagocytosis (solid uptake), Pinocytosis (liquid uptake), Receptor-mediated endocytosis (specific intake).
• Exocytosis: Release of substances from cells by vesicles.

Cytoskeleton Functions

• Support cell structure, organelles organization, cell division, movement facilitation (muscle contraction, cilia/flagella functions).

Ribosomes

• Synthesize proteins: Bound ribosomes (export or membrane), Free ribosomes (for internal use).

Golgi Apparatus

• Modify, store and package proteins for transport.

Cell Cycle

• Interphase: G1 (growth), S (DNA replication), G2 (preparation for division).
• Mitosis: Prophase, Metaphase, Anaphase, Telophase, followed by Cytokinesis.