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CYTOLOGY

CYTOLOGY. THE STUDY OF CELLS - STRUCTURE. GENERAL. Cell = Smallest Living Unit Produced by Cell Division or Fertilization Surrounded by Interstitial / Extracellular Fluid Components: Plasma (Cell) Membrane Cytoplasm Organelles. THE PLASMA MEMBRANE.

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CYTOLOGY

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  1. CYTOLOGY THE STUDY OF CELLS - STRUCTURE

  2. GENERAL • Cell = Smallest Living Unit • Produced by Cell Division or Fertilization • Surrounded by Interstitial / Extracellular Fluid • Components: • Plasma (Cell) Membrane • Cytoplasm • Organelles

  3. THE PLASMA MEMBRANE • Phospholipid bilayer: Hydrophobic tails and hydrophilic heads, selectively permeable • Proteins: Peripheral and integral • Enzymes • Receptors • Transport • Anchors • Carbohydrates: Superficial recognition sites

  4. THE PLASMA MEMBRANE cont. • Fluid Mosaic Model (mosaic of floating proteins) • Functions of Plasma Membrane: • Physical Barrier (Selective!) • Regulates Exchange with Environment • Sensitive to Extracellular Environment • Structural Support

  5. THE PLASMA MEMBRANE

  6. CYTOPLASM • Material Between Plasma Membrane & Nucleus • Components • Cytosol (water + nutrients & other solutes) • Organelles (excludes nucleus) • Inclusions (stored materials) • Functions: Site of chemical reactions

  7. ORGANELLES • “Little Organs” • Membranous organelles • Membrane isolates secretions, enzymes or toxins • Non-membranous organelles

  8. NUCLEUS(Membranous) • Double Nuclear Membrane with Pores • Nucleoplasm • Nucleolus • Organelle in nucleus (non-membranous) • Assembles ribosomes • DNA • Chromatin - loose; protein synthesis • Chromosomes - dense, rodlike; cell division

  9. STRUCTURE OF THE NUCLEUS

  10. ENDOPLASMIC RETICULUM (Membranous) • Smooth endoplasmic reticulum (SER) • Synthesis of Carbohydrates, Steroids & other Lipids • Storage (Synthesized Materials or Ca+) • Rough endoplasmic reticulum (RER) • Attached Ribosomes • Protein synthesis for “export” or inclusion in cell membrane

  11. GOLGI COMPLEX/APPARATUS (Membranous) • Structure: • Flattened Membranous Sacs • Function: • Modifies & packages proteins • Source of lysosomes • Renewal/modification of plasma membrane

  12. MITOCHONDRIA (Membranous) • Structure: Double membrane • Function: Production of ATP (95%), cellular energy • Contains DNA • Self-Replicating

  13. MITOCHONDRIA

  14. LYSOSOMES (Membranous) • Structure: Vesicles filled with Digestive Enzymes (“Suicide Bags”) • Function: • Digestion within the cell • Defense • Recycle worn-out cells

  15. Peroxisomes • Membranous sacs of enzymes • Detoxify harmful/dangerous substances • Alcohol • Formaldehyde • Free Radicals

  16. VACUOLES AND VESICLES (Membranous) • Structure: Membranous Sac • Function: Storage, Endocytosis, Exocytosis

  17. FORMATION OF VESICLES

  18. RIBOSOMES (Non-membranous) • Structure: Two subunits (rRNA + protein) • Function: Protein synthesis • Fixed or Free

  19. CENTROSOMES AND CENTRIOLES (Non-membranous) • Centrosome: “Cell center” • Area of cytoplasm • Microtubule formation center • Contains Centrioles • Centrioles: • Microtubules • Form Mitotic Spindle

  20. CYTOSKELETON (Non-membranous) • Network of protein structures • Acts as cell’s “muscles & bones” • Determines cell shape • Supports organelles • Involved in internal transport & cellular movements

  21. CILIA & FLAGELLA (Non-membranous) • Cilia – short, numerous, move substances over free surfaces • Flagella – long, singular, move cell • Microvilli – thin folds of cell membrane, increase surface area to maximize absorption

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