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

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

6. 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

7. THE PLASMA MEMBRANE

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

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

10. 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

11. STRUCTURE OF THE NUCLEUS

12. 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

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

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

17. MITOCHONDRIA

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

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

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

21. FORMATION OF VESICLES

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

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

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

28. 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