1. Chapter 4 A Tour of the Cell

2. History of Cells u Robert Hooke - Observed cells in cork. u Coined the term "cells” in 1665.

3. History of Cells u 1833 - Robert Brown, discovered the nucleus. u 1838 - M.J. Schleiden, all plants are made of cells. u 1839 - T. Schwann, all animals are made of cells. u 1840 - J.E. Purkinje, coined the term “protoplasm”.

4. Cell Theory u All living matter is composed of one or more cells. u The cell is the structural and functional unit of life.

5. R. Virchow u “Omnis cellula e cellula” u All cells are from other cells.

7. Why Are Cells So Small? u Cell volume to surface area ratios favor small size. u Big enough to perform all functions but have enough surface area

8. u Nucleus to cytoplasm consideration (control all areas). u Metabolic requirements.

10. Basic Cell Organization u Membrane u Nucleus u Cytoplasm u Organelles

11. Animal Cell

12. Plant Cell

13. Membrane u Separates the cell from the environment. u Boundary layer for regulating the movement of materials in/out of a cell.

14. Cytoplasm or Cytosol u Cell substance between the cell membrane and the nucleus. u The “fluid” part of a cell. Exists in two forms: u gel - thick u sol - fluid

15. Organelle u Term means "small organ” Formed body in a cell with a specialized function. u Important in organizational structure of cells.

16. Organelles - function u Way to form compartments in cells to separate chemical reactions. u Keeps various enzymes separated in space.

17. Nucleus u Most conspicuous organelle. u usually spherical, but can be lobed or irregular in shape.

18. Structure u Nuclear membrane u Nuclear pores u Nucleolus u Chromatin

20. Nuclear Membrane u Double membrane u Inner membrane supported by a protein matrix to provide shape

21. Nuclear Pores u Allow things in and out of nucleus u Ex. mRNA during transcription

22. Nucleolus u Dark staining area in the nucleus. u 0 - 4 per nucleus. u Storage area for ribosomes.

23. Chromatin u Chrom: colored u - tin: threads u DNA and Protein in a “loose” format. Will form the cell’s chromosomes.

24. Nucleus - Function u Contains the genetic instructions to make proteins and more DNA

25. Ribosomes u Structure: 2 subunits made of protein and rRNA. No membrane. u Function: protein synthesis. u Site of translation

27. Subunits u Large: u 45 proteins u 3 rRNA molecules u Small: u 23 proteins u 1 rRNA molecule

28. Locations u Free in the cytoplasm - make proteins for use in cell. u Membrane bound - make proteins that are exported from the cell. (on rough ER)

29. Endomembrane System u Membranes that are related through direct physical continuity or by the transfer of membrane segments called vesicles.

30. Endomembrane System

31. Endoplasmic Reticulum u Often referred to as ER. u Makes up to 1/2 of the total membrane in cells. u Often continuous with the nuclear membrane.

33. Structure of ER u Folded sheets or tubes of membranes. u Very “fluid” in structure with the membranes constantly changing size and shape.

34. Types of ER u Smooth ER: no ribosomes. u Used for lipid synthesis, carbohydrate storage, detoxification of poisons. u Rough ER: with ribosomes. u Makes secretory proteins.

35. Golgi Apparatus or Golgi Body u Structure: parallel array of flattened cisternae. (looks like a stack of pancakes) u 3 to 20 per cell. u Likely an outgrowth of the ER system.

37. Function of Golgi Bodies u Processing - modification of ER products (lipids, carbs). u Distribution - packaging of ER products for transport. u Mailman of the cell

38. Golgi Vesicles u Small sacs of membranes that bud off the Golgi Body. u Transportation vehicle for the modified ER products.

39. Lysosome u Structure: Single membrane. u Made from the Golgi apparatus.

40. Function u Breakdown and degradation of cellular materials. u Contains enzymes for fats, proteins, polysaccharides, and nucleic acids. u Over 40 types known.

43. Lysosomes u Important in cell death. u Missing enzymes may cause various genetic enzyme diseases. u Examples: Tay-Sachs, Pompe’s Disease

44. Vacuoles u Structure - single membrane, usually larger than the Golgi vesicles. u Function - depends on the organism.

45. Protists u Contractile vacuoles - pump out excess water. u Food vacuoles - store newly ingested food until the lysosomes can digest it.

47. Plants u Large single vacuole when mature making up to 90% of the cell's volume.

49. Function u Water regulation. u Storage of ions. u Storage of hydrophilic pigments. (e.g. red and blues in flower petals).

50. Function: Plant vacuole u Used to enlarge cells and create turgor pressure. u Enzymes (various types). u Store toxins. u Coloration.

51. Microbodies: Peroxisomes u Structure: single membrane. u Often have a granular or crystalline core of enzymes.

52. Function u Specialized enzymes for specific reactions. u Peroxisomes: use up/break down hydrogen peroxide.

53. Enzymes in a crystal

54. u End of part 1 u Homework

55. Mitochondria u Structure: 2 membranes. The inner membrane has more surface area than the outer membrane. u Matrix: inner space. u Intermembrane space: area between the membranes.

57. Inner Membrane u Folded into cristae. u Amount of folding depends on the level of cell activity. u Contains many enzymes. u ATP generated here.

58. Function u Cell Respiration - the release of energy from food. u Major location of ATP generation. u “Powerhouse” of the cell.

59. Mitochondria notes u Have ribosomes (small size). u Have their own DNA. u Can reproduce themselves. u May have been independent cells at one time.

60. Chloroplasts u Structure - two outer membranes. u Complex internal membrane. u Fluid-like stroma is around the internal membranes.

62. Inner or Thylakoid Membranes u Arranged into flattened sacs called thylakoids. u Some regions stacked into layers called grana. u Contain the green pigment chlorophyll.

63. Function u Photosynthesis - the use of light energy to make food. u Where does this food go to produce energy?

64. Chloroplasts notes u Contain ribosomes (small size). u Contain DNA. u Can reproduce themselves. u May have been independent cells at one time.

65. Cytoskeleton u Network of rods and filaments in the cytoplasm.

67. Functions u Cell structure and shape. u Cell movement. u Cell division - helps build cell walls and move the chromosomes apart.

68. Components u Microtubules u Microfilaments u Intermediate Filaments

70. Microtubules u Structure - small hollow tubes made of repeating units of a protein dimer.  Level 3-Size - 25 nm diameter with a 15 nm lumen. Can be 200 nm to 25  m in length.

71. Tubulin u Protein in microtubules.  Dimer -  and  tubulin.

72. Microtubules u Regulate cell shape. u Tracks for motor molecules.

74. Microtubules u Form cilia and flagella. u Internal cellular movement. u Make up centrioles, basal bodies and spindle fibers.

75. Centrioles u Usually one pair per cell, located close to the nucleus. u Found in animal cells. u 9 sets of triplet microtubules. u Help in cell division.

76. Microfilaments u 5 to 7 nm in diameter. u Structure - two intertwined strands of actin protein.

79. Microfilaments are stained green.

80. Functions u Muscle contraction. u Cytoplasmic streaming. u Pseudopodia. u Cleavage furrow formation. u Maintenance and changes in cell shape.

81. Intermediate filaments u Fibrous proteins supercoiled into cables u Functions: Maintain cell shape u Anchor organelles

82. Cytoskeleton u Very dynamic; changing in composition and shape frequently. u Cell is not just a "bag" of cytoplasm within a cell membrane.

83. Cell Wall u Nonliving jacket that surrounds some cells. u Found in: u Plants u Prokaryotes u Fungi u Some Protists

84. Cell Walls u May be made of other types of polysaccharides and/or silica. u Function as the cell's exoskeleton for support and protection.

85. Extracellular Matrix - ECM u Fuzzy coat on animal cells. u Helps glue cells together. u Made of glycoproteins and collagen. u Evidence suggests ECM is involved with cell behavior and cell communication.

87. Intercellular Juctions u Plants-Plasmodesmata

88. Plasmodesmata u Channels between cells through adjacent cell walls. u Allows communication between cells. u Also allows viruses to travel rapidly between cells.

89. Intercellular Juctions u Animals: u Tight junctions u Anchoring junctions u Gap junctions

91. Tight Junctions u Very tight fusion of the membranes of adjacent cells. u Seals off areas between the cells. u Lining of digestive tract

93. Anchoring junctions u Does not close off the area between adjacent cells. u Coordination of movement between groups of cells. u Ex: Tissue subject to stretching (skin and muscle)

95. Gap Junctions u Open channels between cells, similar to plasmodesmata. u Allows “communication” between cells. u Ex: heart muscle, embryos

97. Types of Cells u Prokaryotic - lack a nucleus and other membrane bound structures. u Eukaryotic - have a nucleus and other membrane bound structures.

98. Both Have: u Membrane u Cytosol u Ribosomes (but the size is different)

99. ProkaryoticEukaryotic Nucleus

100. Prokaryotes u Bacteria u Capsule- sticky outer layer u Cell wall- protects and maintains shape u Plasma membrane- controls movement of materials

101. Prokaryotes u Pili- used for attachment u Joins bacteria together for transfer of DNA u Flagella- allow for cell motility (longer than pili)

102. Prokaryotes u Ribosomes- protein synthesis u Nucleoid- Contains the DNA

103. Calculating in microscopes u Actual size of specimen u Measure the field of vision while looking through the microscope (~1.5mm) u Then figure the % of field the specimen occupies and multiply by field of vision

104. Continued u Field of vision is 1.4mm or 1400 micrometers u Specimen is 60% of field of vision u 1400 x.60 =840 micrometers

105. Calculating u Magnification u Scale bar next to drawing Magnification= size of image / size of specimen

106. u Size of image = 10 mm or 10000 micrometers u Size of specimen is 10 micrometers u 10000 / 10 is 1000x magnified

107. Magnification u Image size u 12.5 cm or 125,000 Micrometers Specimen size (using scale) 4.5 micrometers So 125,000/4.5= 27,777x

108. Summary u Answer: Why is Life cellular and what are the factors that affect cell size? u Be able to identify cellular parts, their structure, and their functions.