1. EUKARYOTE CELL ULTRASTRUCTURE

2. Primary Cell Structure That which can be seen using the light microscope © P Billiet © 2010 Paul Billiet ODWSODWS

3. Ultrastructure That which can be observed under the electron microscope

4. EUKARYOTE CELL ULTRASTRUCTURE 20 nm diameterProtein synthesisRibosome 26 to 56 nm thickSupport, Golgi apparatus synthesis Endoplasmic Reticulum (ER) Cisternae: 0.5µm thick, l-3µm diameter Secretion, reprocessing, lysosome synthesis Golgi apparatus 0.5 to 3.0 µm diameterDigestion, recycling & isolation Lysosome 5 to 10 µm diameterPhotosynthetic pathwaysChloroplast 1.0 to 12.5 µmRespiration pathwaysMitochondrion 10 µm diameterCell division, protein synthesis Nucleus DIMENSIONSMAIN FUNCTIONSORGANELLE © 2010 Paul Billiet ODWSODWS

5. NUCLEUS (latin kernel) TEM Nucleus of a rat hepatocyte Image Credit: www.sinauer.com

6. NUCLEUS (pl nuclei) Usually spherical occupying up to 75% of the cell volume 10 µm © 2010 Paul Billiet ODWSODWS

7. NUCLEUS Chemical composition Protein: Up to 90%, HISTONES rich in basic amino acids. Deoxyribonucleic Acid (DNA) about 20% (acidic) Ribonucleic Acid (RNA) 5 to 20% Nuclei usually contain about 10% CHROMATIN = Histone + DNA = NUCLEOPROTEIN. © 2010 Paul Billiet ODWSODWS

8. NUCLEUS Functions Main site of DNA in eukaryotic cells Preservation, replication and expression of genetic information It makes RNA for protein synthesis It copies DNA for cell division © 2010 Paul Billiet ODWSODWS

9. MITOCHONDRION (gk mitos = thread khondrion = granule) Image Credit: University of GeorgiaUniversity of Georgia TEM of mitochondrion from mouse kidney cell

10. MITOCHONDRION (pl. mitochondria) outer membrane inner membrane Mitochondrial envelope Inter membrane space Cristae Inner matrix 1.0 to 12.5 µm © 2010 Paul Billiet ODWSODWS

11. MITOCHONDRION Pigments Cytochromes Functions The inner membrane contains the enzyme necessary for the synthesis of Adenosine Triphosphate (ATP) The mitochondria are closely associated with the pathways of respiration These metabolic pathways are divided up and supported by the membranes © 2010 Paul Billiet ODWSODWS

12. CHLOROPLAST (Gk chloros = green plast = form or shape) Image Credit: University of WisconsinUniversity of Wisconsin TEM chloroplast

13. CHLOROPLAST outer membrane inner membrane Chloroplast envelope Starch grains Grana Frets Thylakoid membrane Stroma 5 to 10 µm © 2010 Paul Billiet ODWSODWS

14. CHLOROPLAST Pigments Mainly chlorophylls with carotenoids and others Function: Photosynthesis The metabolic pathways are closely associated with the membranes as in the case of the mitochondrion © 2010 Paul Billiet ODWSODWS

15. Organelles and evolution Both chloroplasts and mitochondria are double membrane bound They involved in energy reactions They contain extranuclear DNA and characteristic small ribosomes of their own This has led biologists to believe that there may be some similarity in their origins in the cells of eukaryotes. The endosymbiotic theory © 2010 Paul Billiet ODWSODWS

16. LYSOSOME Image Credit: http://www.biokurs.de/http://www.biokurs.de/

17. LYSOSOME Not discovered by electron microscopy but by centrifugation and enzyme analysis Some scientists suggest that they are not present in plant cells Structure: Simple, spherical, single membrane bound Lysosomes contain a large number of CATABOLIC enzymes. Catabolic enzymes digest materials by hydrolysis © 2010 Paul Billiet ODWSODWS

18. Enzymes found in lysosomes ENZYMESUBSTRATE Acid phosphatasePhosphate esters Acid ribonucleaseRNA Acid deoxyribonucleaseDNA GlycosidasesPolysaccharides ProteaseProteins and peptides LipaseLipids PhospholipasePhospholipids More than 40 types of enzymes are known to occur in lysosomes. © 2010 Paul Billiet ODWSODWS

19. LYSOSOME Function Digestion of compounds taken in by the cell by endocytosis Recycling of material within the cell © 2010 Paul Billiet ODWSODWS

20. GOLGI APPARATUS Image Credit: International Journal of MorphologyInternational Journal of Morphology

21. GOLGI APPARATUS Golgi vesicles transport the materials from one cisterna to the next Cisternae are flattened sacs Transport vesicles bring material from the endoplasmic reticulum to the entry face Golgi vesicles take transformed materials from the exit face to their destination © 2010 Paul Billiet ODWSODWS

22. GOLGI APPARATUS Functions Processing and packaging Synthesising lysosomes to contain the potentially dangerous catabolic enzymes Producing secretory vesicles e.g. mucus Making more plasma membrane © 2010 Paul Billiet ODWSODWS

23. ENDOPLASMIC RETICULUM (ER) Image Credit: www.lifesci.sussex.ac.uk/www.lifesci.sussex.ac.uk/

24. ENDOPLASMIC RETICULUM (ER) Rough ER Smooth ER Transport vesicles Lumen which can occupy up to 10% of the cell volume Membranes © 2010 Paul Billiet ODWSODWS

25. ER Functions Not easy to study the ER is that it is difficult to extract intact ER starts the biosynthetic pathways form many protein and lipid molecules in the cell These continue in the Golgi apparatus Rough ER has ribosomes attached to it as opposed to Smooth ER The proteins are made on rough ER will eventually be secreted outside the cell © 2010 Paul Billiet ODWSODWS

26. RIBOSOME Image Credit: www.palaeos.com/www.palaeos.com/ Image Credit: British Society for Cell BiologyBritish Society for Cell Biology

27. RIBOSOME NOT membrane bound Found both in pro- and eukarotes The subunits are synthesised separately in the nucleolus of the nucleus of eukaryotes Large ribosome subunit Small ribosome subunit © 2010 Paul Billiet ODWSODWS

28. RIBOSOME Distribution in the cytoplasm single free-floating attached to rough ER linked together as a POLYRIBOSOME or POLYSOME Function: Protein synthesis Chemical composition Protein + RNA in other words it is a nucleoprotein © 2010 Paul Billiet ODWSODWS

29. The relationship between organelles Nucleus ER Golgi apparatus Lysosome Ribosomes Endocytosis Exocytosis © 2010 Paul Billiet ODWSODWS