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Eukaryotic cells

Main Summary Cells are the fundamental structural and functional units of all living organisms. They can be classified into two main types: prokaryotic and eukaryotic, each with unique characteristics and functions. 1. Cell Theory Key Principles of Cell Theory • All living organisms are made up of cells • Cell is the basic structural and functional unit of life • All cells arise from pre-existing cells Modern Additions to Cell Theory • All cells contain DNA as their genetic material • Energy flow (metabolism) occurs within cells • All cells have the same basic chemical composition 2. Types of Cells 2.1 Prokaryotic Cells • Simple, primitive cells • No true nucleus (DNA in cytoplasm) • No membrane-bound organelles • Examples: Bacteria, Archaea Bacterial Cell Structure • Cell Envelope: Three-layered structure • Outermost layer: Glycocalyx • Middle layer: Cell wall • Inner layer: Plasma membrane Gram Staining Classification 1. Gram-Positive Bacteria • Stain Color: Purple • Thick peptidoglycan layer • No outer membrane • More sensitive to antibiotics • Examples: • Staphylococcus aureus • Streptococcus pneumoniae 2. Gram-Negative Bacteria • Stain Color: Pink/red • Thin peptidoglycan layer • Outer membrane with lipopolysaccharides • More resistant to antibiotics • Examples: • Escherichia coli • Salmonella 2.2 Eukaryotic Cells • Complex cells with a true nucleus • Membrane-bound organelles • Found in: Plants, Animals, Fungi, Protists Plant vs Animal Cells Comparison | Feature | Plant Cell | Animal Cell | |---------|-----------|-------------| | Cell Wall | Present | Absent | | Shape | Rectangular | Round/Irregular | | Chloroplasts | Present | Absent | | Vacuole | One large central | Many small | | Centrioles | Absent | Present | | Energy Storage | Starch | Glycogen | | Lysosomes | Rare | Common | 3. Cell Organelles Key Organelles • Nucleus: Control center, contains DNA • Mitochondria: Powerhouse of the cell • Endoplasmic Reticulum: Protein and lipid synthesis • Golgi Apparatus: Protein modification and packaging • Ribosomes: Protein synthesis • Lysosomes: Digestion and waste removal • Chloroplasts (in plant cells): Photosynthesis 4. Cell Functions • Growth and repair • Energy production • Material transport • Reproduction • Response to stimuli Historical Notes • Anton van Leeuwenhoek: Discovered bacteria • Robert Hooke (1665): Described microscope • Matthias Schleiden (1838): All plants made of cells • Theodor Schwann (1839): All animals made of cells • Rudolf Virchow (1855): Cells arise from pre-existing cells Prokaryotes/Eukaryotes    • Prokaryotes/Eukaryotes   Mitochondria(structure and its functions)@Botanist Meena    • Mitochondria(structure and its functions)@...