2. Chapter 4: Cellular Organization

3. The cell is the fundamental unit of life. The modern theory of cellular organization states that: 1. All living organisms are composed of cells. 2. All new cells are derived from other cells. 3. Cells contain the hereditary material of an organism which is passed from parent to daughter cells. 4. All metabolic processes take place within cells.

4. Microscopy Structure of the light microscope: uses light to view specimens Simple microscope - uses one magnifying lens

5. Microscopy Structure of the light microscope: uses light to view specimens Simple microscope - uses one magnifying lens Compound microscope - use two magnifying lenses

6. Microscopy Structure of the light microscope: uses light to view specimens Simple microscope - uses one magnifying lens Compound microscope - use two magnifying lenses Resolution (resolving power) : the degree of detail which can be seen with a microscope Staining and preparation of slides for the light microscope - in order to make transparent material visible or to enhance the colour of a specimen

7. Structure of the electron microscope - uses electron beam to pass through specimen and directed onto a screen which develops black & white photographs (photoelectronmicrographs) - two types: transmission electron microscope - for very thin object to produce flat images

9. Structure of the electron microscope - uses electron beam to pass through specimen and directed onto a screen which develops black & white photographs (photoelectronmicrographs) - two types: transmission electron microscope - for very thin object to produce flat images scanning electron microscope - for producing three- dimensional images Preparation and staining of material for an electron microscope - a long and complicated process

10. Comparison between light and electron microscopes Light MicroscopeElectron Microscope

11. Comparison between light and electron microscopes Light MicroscopeElectron Microscope AdvantagesDisadvantages

12. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Advantages 1. Cheap Disadvantages

13. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Advantages 1. Cheap Disadvantages Expensive

14. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Advantages 1. Cheap 2. Small & portable Disadvantages Expensive

15. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Advantages 1. Cheap 2. Small & portable Disadvantages Expensive Large and fixed for use

16. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Advantages 1. Cheap 2. Small & portable 3. Unaffected by magnetic field Disadvantages Expensive Large and fixed for use

17. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Advantages 1. Cheap 2. Small & portable 3. Unaffected by magnetic field Disadvantages Expensive Large and fixed for use Affected by magnetic field

18. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Advantages 1. Cheap 2. Small & portable 3. Unaffected by magnetic field 4. Easy to prepare materials Disadvantages Expensive Large and fixed for use Affected by magnetic field

19. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Advantages 1. Cheap 2. Small & portable 3. Unaffected by magnetic field 4. Easy to prepare materials Disadvantages Expensive Large and fixed for use Affected by magnetic field Complicated procedures to prepare materials

20. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Advantages 1. Cheap 2. Small & portable 3. Unaffected by magnetic field 4. Easy to prepare materials 5. Materials rarely distorted by preparation Disadvantages Expensive Large and fixed for use Affected by magnetic field Complicated procedures to prepare materials

21. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Advantages 1. Cheap 2. Small & portable 3. Unaffected by magnetic field 4. Easy to prepare materials 5. Materials rarely distorted by preparation Disadvantages Expensive Large and fixed for use Affected by magnetic field Complicated procedures to prepare materials Materials may be distorted during preparation

22. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Advantages 1. Cheap 2. Small & portable 3. Unaffected by magnetic field 4. Easy to prepare materials 5. Materials rarely distorted by preparation 6. Natural colour of specimen can be seen Disadvantages Expensive Large and fixed for use Affected by magnetic field Complicated procedures to prepare materials Materials may be distorted during preparation

23. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Advantages 1. Cheap 2. Small & portable 3. Unaffected by magnetic field 4. Easy to prepare materials 5. Materials rarely distorted by preparation 6. Natural colour of specimen can be seen Disadvantages Expensive Large and fixed for use Affected by magnetic field Complicated procedures to prepare materials Materials may be distorted during preparation All images are in black and white

24. Comparison between light and electron microscopes Light MicroscopeElectron Microscope DisadvantagesAdvantages

25. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Disadvantages 1 Magnifies up to 2000 x Advantages

26. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Disadvantages 1 Magnifies up to 2000 x Advantages Magnifies > 500,000 x

27. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Disadvantages 1 Magnifies up to 2000 x 2 Depth of field is restricted Advantages Magnifies > 500,000 x

28. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Disadvantages 1 Magnifies up to 2000 x 2 Depth of field is restricted Advantages Magnifies > 500,000 x A greater depth of field

29. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Disadvantages 1 Magnifies up to 2000 x 2 Depth of field is restricted 3 Lower resolution Advantages Magnifies > 500,000 x A greater depth of field

30. Comparison between light and electron microscopes Light MicroscopeElectron Microscope Disadvantages 1 Magnifies up to 2000 x 2 Depth of field is restricted 3 Lower resolution Advantages Magnifies > 500,000 x A greater depth of field Higher resolution

31. Structure of a prokaryote, e.g. a bacterium

32. 4.1 Cytology - the study of cells 4.1.1 The structure of prokaryotic cells primitive cells: in bacteria & blue-green bacteria 4.1.2 Structure of the eukaryotic cell - true cells: develops from prokaryotic cells

34. Advantages of membrane-bounded organelles in eukaryotic cells: 1 Organelle membranes increases the surface area to volume ratio for enzymatic reactions 2 Membrane bound enzymes enable products of reaction close to the next enzyme for faster rates of metabolism 3 Metabolic pathways are better regulation by controlling the first reactant to enter 4 Harmful reactants can be isolated inside the organelle to avoid damage to the cell

35. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells

36. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus

37. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleusA distinct membrane- bounded nucleus

38. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus 2 No chromosomes but circular strands of DNA A distinct membrane- bounded nucleus

39. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus 2 No chromosomes but circular strands of DNA A distinct membrane- bounded nucleus Chromosomes present with DNA

40. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus 2 No chromosomes but circular strands of DNA 3 No membrane-bounded organelles such as mitochondria A distinct membrane- bounded nucleus Chromosomes present with DNA

41. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus 2 No chromosomes but circular strands of DNA 3 No membrane-bounded organelles such as mitochondria A distinct membrane- bounded nucleus Chromosomes present with DNA Membrane-bounded organelles like mitochondria are present

42. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus 2 No chromosomes but circular strands of DNA 3 No membrane-bounded organelles such as mitochondria 4 Smaller ribosomes A distinct membrane- bounded nucleus Chromosomes present with DNA Membrane-bounded organelles like mitochondria are present

43. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus 2 No chromosomes but circular strands of DNA 3 No membrane-bounded organelles such as mitochondria 4 Smaller ribosomes A distinct membrane- bounded nucleus Chromosomes present with DNA Membrane-bounded organelles like mitochondria are present Larger ribosomes

44. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus 2 No chromosomes but circular strands of DNA 3 No membrane-bounded organelles such as mitochondria 4 Smaller ribosomes 5 Flagella (if present) lack the 9+2 fibril structure A distinct membrane- bounded nucleus Chromosomes present with DNA Membrane-bounded organelles like mitochondria are present Larger ribosomes

45. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus 2 No chromosomes but circular strands of DNA 3 No membrane-bounded organelles such as mitochondria 4 Smaller ribosomes 5 Flagella (if present) lack the 9+2 fibril structure A distinct membrane- bounded nucleus Chromosomes present with DNA Membrane-bounded organelles like mitochondria are present Larger ribosomes Flagella have 9+2 fibril arrangement

46. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus 2 No chromosomes but circular strands of DNA 3 No membrane-bounded organelles such as mitochondria 4 Smaller ribosomes 5 Flagella (if present) lack the 9+2 fibril structure 6 No mitosis or meiosis occurs A distinct membrane- bounded nucleus Chromosomes present with DNA Membrane-bounded organelles like mitochondria are present Larger ribosomes Flagella have 9+2 fibril arrangement

47. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus 2 No chromosomes but circular strands of DNA 3 No membrane-bounded organelles such as mitochondria 4 Smaller ribosomes 5 Flagella (if present) lack the 9+2 fibril structure 6 No mitosis or meiosis occurs A distinct membrane-bounded nucleus Chromosomes present with DNA Membrane-bounded organelles like mitochondria are present Larger ribosomes Flagella have 9+2 fibril arrangement Mitosis &/or meiosis occurs

48. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus 2 No chromosomes but circular strands of DNA 3 No membrane-bounded organelles such as mitochondria 4 Smaller ribosomes 5 Flagella (if present) lack the 9+2 fibril structure 6 No mitosis or meiosis occurs 7 infolding of the cell membrane forms mesosome for respiration A distinct membrane-bounded nucleus Chromosomes present with DNA Membrane-bounded organelles like mitochondria are present Larger ribosomes Flagella have 9+2 fibril arrangement Mitosis &/or meiosis occurs

49. Table 4.1 Comparison of prokaryotic and eukaryotic cells Prokaryotic CellsEukaryotic Cells 1 No distinct nucleus 2 No chromosomes but circular strands of DNA 3 No membrane-bounded organelles such as mitochondria 4 Smaller ribosomes 5 Flagella (if present) lack the 9+2 fibril structure 6 No mitosis or meiosis occurs 7 infolding of the cell membrane forms mesosome for respiration A distinct membrane-bounded nucleus Chromosomes present with DNA Membrane-bounded organelles like mitochondria are present Larger ribosomes Flagella have 9+2 fibril arrangement Mitosis &/or meiosis occurs 7 mitochondria for respiration