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CYTOLOGY & HISTOLOGY Lecture three

CYTOLOGY & HISTOLOGY Lecture three. DR. ASHRAF SAID. Review. Of the second lecture. Concept 3. The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes. Start. Of this lecture. Objectives of lecture three.

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CYTOLOGY & HISTOLOGY Lecture three

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  1. CYTOLOGY & HISTOLOGYLecture three DR. ASHRAF SAID

  2. Review Of the second lecture

  3. Concept 3 • The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes

  4. Start Of this lecture

  5. Objectives of lecture three The Endoplasmic Reticulum: Biosynthetic Factory Lysosomes: Digestive Compartments

  6. Concept 4 The endomembrane system regulates protein traffic and performs metabolic functions in the cell • The endomembrane system • Includes many different structures

  7. The Endoplasmic Reticulum: Biosynthetic Factory • The endoplasmic reticulum (ER) • Accounts for more than half the total membrane in many eukaryotic cells

  8. Smooth ER Nuclear envelope Rough ER ER lumen Cisternae Ribosomes Transitional ER Transport vesicle 200 µm Smooth ER Rough ER The ER membrane • Is continuous with the nuclear envelope Figure 1.12

  9. The ER membrane • There are two distinct regions of ER • Smooth ER, which lacks ribosomes • Rough ER, which contains ribosomes

  10. The smooth ER Synthesizes lipids Metabolizes carbohydrates Stores calcium Detoxifies poison The rough ER Has bound ribosomes Produces proteins and membranes, which are distributed by transport vesicles Functions of ER Rough Smooth

  11. The Golgi Apparatus: Shipping and Receiving Center • The Golgi apparatus • Receives many of the transport vesicles produced in the rough ER • Consists of flattened membranous sacs called cisternae

  12. Functions of the Golgi apparatus include • Modification of the products of the rough ER • Manufacture of certain macromolecules

  13. cis face (“receiving” side of Golgi apparatus) 5 3 4 6 2 1 Vesicles coalesce to form new cis Golgi cisternae Vesicles move from ER to Golgi 0.1 0 µm Vesicles also transport certain proteins back to ER Cisternae Cisternal maturation: Golgi cisternae move in a cis- to-trans direction Vesicles form and leave Golgi, carrying specific proteins to other locations or to the plasma mem- brane for secretion trans face (“shipping” side of Golgi apparatus) Vesicles transport specific proteins backward to newer Golgi cisternae Functions of the Golgi apparatus Golgi apparatus Figure 1.13 TEM of Golgi apparatus

  14. Lysosomes:Digestive Compartments • A lysosome • Is a membranous sac of hydrolytic enzymes • Can digest all kinds of macromolecules

  15. 1 µm Nucleus Lysosome Hydrolytic enzymes digest food particles Food vacuole fuses with lysosome Lysosome contains active hydrolytic enzymes Digestive enzymes Lysosome Plasma membrane Digestion Food vacuole (a) Phagocytosis: lysosome digesting food Lysosomes carry out intracellular digestion by phagocytosis Figure 1.14 A

  16. Figure 1.14 B Lysosome containing two damaged organelles 1 µ m Mitochondrion fragment Peroxisome fragment Lysosome fuses with vesicle containing damaged organelle Hydrolytic enzymes digest organelle components Lysosome Digestion Vesicle containing damaged mitochondrion (b) Autophagy: lysosome breaking down damaged organelle Autophagy

  17. Tank you End of first Lecture

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