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)@...