Organization of the Cell

1. Organization of the Cell

2. Cell Theory Cells are the basic living units of organization and function in all organisms and all cells come from other cells

3. Cell Theory The players: Matthias Schleiden- German botanist (1838) Theodor Schwann- German zoologist (1839) Rudolph Virchow- German professor of pathology (1855)

4. Schleiden and Schwann The first to point out that all plants and animals are composed of cells. 1838

5. Rudolph Virchow The first to observe cells dividing 1855

6. History of the Microscope • Robert Hooke examined a thin piece of cork using a compound microscope- noticed the boxes in the thin slice and called them “cells” 1665 ?

7. History of the Microscope Anton van Leeuwenhoek viewed living cells with 200 magnification single lenses of his own construction. His important discoveries include bacteria, protists, blood cells, and sperm cells. 1670s Dutch Scientist

8. Van Leeuwenhoek’s Microscope

9. 1800

10. 1860

11. 1880

12. 1890

13. 1899

14. 1908

15. 1930

16. 1951

17. 1970

18. 2004 Nikon ‘confocal’ microscope and, “No, I don’t know how much it costs.”

19. Electron Microscope Invented in 1930s by (believe it or not) German scientists Max Knott and Ernst Ruska

20. Transmission Electron Microscope • 2-D Image • Image not living • 10,000X to 100,000X • Electron beam passes through the specimen • Specimen is thinly sliced

21. Scanning Electron Microscope • 3-D imaging • Image not living • 1,000X-10,000X magnification • Image is coated with a thin film of metal and the electron beams are collected as they bounce off of the specimen

22. Prokaryotic Cells Bacteria are prokaryotic cells. All other known organisms consist of ….. Eukaryotic Cells

23. Prokaryotic Cells • Structurally simpler than eukaryotic cells • Nuclear material not enclosed in a membrane • Ribosomes smaller than Euk. • Lack of membrane bound organelles

27. Cheek cells bacteria

28. Eukaryotic Cells • Membrane bound organelles • Cell Nucleus • Ribosomes • Endoplasmic reticulum • Golgi complex • Lysosomes • Peroxisomes • Vacuoles • Mitochondria • Chloroplasts

29. Membrane Bound Organelles The ‘stuff’ outside the nucleus and inside the cell membrane, suspended in cytoplasm

30. mitochondria ribosomes Vacuoles Endoplasmic reticulum Peroxisomes Golgi complex Plastids Lysosomes Membrane Bound Organelles Just to name a few

31. Cell Nucleus Cell Nucleus Contains nucleolus and chromosomes (DNA)

32. The Nucleus

33. Cell Nucleus • Typically in the center of the cell • Most cells have a single nucleus

34. Nuclear Envelope • Controls traffic between the nucleus and the cytoplasm • Pores in the nuclear membrane allow materials to pass in and out of the • nucleus

36. Nucleus – a closer look

37. Nuclear Envelope

38. EM View of Envelope

39. A closer look at the envelope

40. Nuclear Lamina • Inside the nucleus • Formed by intermediate filaments • Important in the timing of the disorganization of the membrane during cell division and the ensuing redevelopment

41. Lamina

42. Chromatin • When dividing, DNA takes the form of chromosomes • When not dividing, the DNA takes a looser form called chromatin

43. Loose Chromatin

44. Ribosomal Subunits • Eukaryotic ribosomal subunits are assembled in the nucleolus • Ribosomes are composed of two subunits

45. Ribosomes • Ribosomes manufacture proteins • Ribosomes may be free or may be attached to the endoplasmic reticulum

47. Endoplasmic Reticulum

48. Endoplasmic Reticulum • Major manufacturing center- proteins • Extends from the nuclear membrane into the cytoplasm • Lumen- the space enclosed by the ER- typical intracellular membrane

49. The Cytosol side of the ER may be studded with ribosomes

50. Rough ER • Site of protein synthesis • Proteins formed may be transferred to other sites within the cell in transport vesicles