Cell Architecture

1. Cell Architecture

2. CELL THEORY • Mathias Schleiden and Theodore Schwann • Prokaryotic cell • Eukaryotic cell – plant cell and animal cell • Figure 9-1

3. Animal cell substructures

4. Single and Double Membrane Substructures • Single Membrane Structures • Plasma Membrane • Endoplasmic Reticulum • Golgi Apparatus • Lysosome • Peroxisome • Endosome • Double membrane structures – Nucleus and Mitochondria

5. Plant Cell Substructures

6. Single and Double Membrane Substructures • Single Membrane Structures • Plasma Membrane • Endoplasmic Reticulum • Golgi Apparatus • Lysosome • Peroxisome • Endosome • Double membrane structures – Nucleus and Chloroplast

7. Plasma Membrane Chapter10 Fig.10-1

8. EM OF A THIN ERYTHROCYTE MEMBRANE

9. How do endosomes work?

10. Lysosomes • Internal compartment is very different form the cytosol –more acidic pH • Degrades substances that are obsolete • Phagocytosis and Endocytosis • All lysosmal enzymes are acid hydrolases • Tays Sach’s disease – defect in enzyme catalyzing a step in the lysosomal breakdown of gangliosides.

11. Autophagy

13. Plant Vacuoles • Similar to lysosomes – degradative enzymes • Concentration of solutes is larger inside the vacuole than outside • Stores small molecules and is permeable to water • Elongation of the plant is related to water uptake by the vacuole

14. EM OF A PLANT CELL

15. Peroxisomes • 0.2-1.0 micrometer in diameter • Oxidases • Catalase 2H₂O₂ -----> 2H₂O + O₂ • Main site of fatty acid peroxidation • Various toxic molecules that enter the body are degraded here

16. Mitochondrial vs. Peroxisomal Oxidation Fig. 12-12

17. Endoplasmic Reticulum • Smooth ER: • Synthesis of Fatty Acids and Lipids • Metabolism of Carbohydrates • Detoxify Drugs and Poisons • Rough ER: • Synthesis of Secretory Proteins, Membrane and Organelle Proteins

18. ROUGH ER IS MADE OF RIBOSOMES

19. RIBOSOMES • Composed of rRNA and protein • Site of protein synthesis • Proteins are marked for different organelles or for secretion • Ribosomes are assembled in the nucleolus • Free Ribosomes

20. PROTEIN MODIFICATION IN THE ER SECRETED PROTIENS • GLYCOSYLATION • DISULFIDE BOND FORMATION

21. HORMONE SECRETING CELL FROM RAT PITUITARY

22. Golgi Apparatus

23. Golgi - Function • Flattened membrane vesicles or sacs • Cis, medial and trans -Golgi • Proteins targeted for different points in the cell are modified differently • Secretory proteins • Plasma membrane proteins • Membrane or soluble proteins to other organelles

24. HOW SECRETORY PROTEINS ARE TRANSPORTED?

25. ORGANELLES WITH DOUBLE MEMBRANES • MITOCHONDRIA • Power house of the cell • Site of cellular respiration • Organic molecules are used fro ATP synthesis NUCLEUS contains chromosomes, DNA and RNA CHLOROPLAST Site of Photosynthesis

26. EM OF A MITOCHONDRION

27. STRUCTURE OF A MITOCHONDRION

28. OUTER MEMBRANE AND INNER MEMBRANE • OUTER MEMBRANE • 50% lipid and 50% protein • Porin proteins (MW of 10,000) INNER MEMBRANE - CRISTAE

29. POWER HOUSE OF THE CELL

30. Nucleus • Inner membrane and outer membrane • Outer membrane is continuous with rough ER • The intermembrane space is continuous with the lumen of the ER • Nuclear pores and nucleoporins • Heterochromatin • Ribosomal RNA assembly

32. HETEROCHROMATIN

33. CHLOROPLAST • Double membraned organelle • Length is 10µm and thickness of 0.5-2 µm • Sacs - Thylakoids • Stacks are grana • Matrix space called Stroma • Photosynthesis

34. MITOCHONDRIAAND CHLOROPLAST • ATP production • Move around in the cell • Contain their own DNA • Some of their proteins are encoded in the nucleus

35. EM OF A PLANT CHLOROPLAST