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Biol101 chp6-pp-fall10-101024134531-phpapp02
- 1. A Tour of the Cell BIOL 101: General Biology I Chapter 6 Rob Swatski Associate Professor of Biology HACC – York Campus 1
- 2. Cells All organisms made of cells Simplest level of life Structure correlated with function Cells descend from previous cells 2
- 3. 3
- 5. 10 m 1 m 0.1 m 1 cm 1 mm 100 m Human egg Frog egg Chicken egg Length of some nerve and muscle cells Human height Unaidedeye 5
- 6. 1 mm 100 m 10 m 1 m 100 nm 10 nm 1 nm 0.1 nm Atoms Small molecules Lipids Proteins Ribosomes Viruses Smallest bacteria Mitochondrion Most bacteria Nucleus Most plant and animal cells Human egg Lightmicroscopy Electronmicroscopy Super- resolution microscopy 1 cm Frog egg 6
- 7. (a) Brightfield (unstained) (b) Brightfield (stained) TECHNIQUE RESULTS 50 µm 7
- 8. (c) Phase-contrast (d) Differential-interference contrast (Nomarski) TECHNIQUE RESULTS 8
- 12. Fluorescence12
- 14. 14 Confocal
- 15. 15 Electron Microscopes Scanning Electron Microscope (SEM) Transmission Electron Microscope (TEM)
- 16. Scanning electron microscopy (SEM) TECHNIQUE RESULTS Transmission electron microscopy (TEM) 16
- 17. 17 SEM
- 18. 18
- 19. 19 TEM
- 20. 20 Cell Fractionation Separate organelles Correlate cytology with biochemistry Homogenization Ultracentrifugation Differential centrifugation
- 22. 1,000 g 10 min Supernatant 20,000 g 20 min 80,000 g 60 min 150,000 g 3 hr Pellet rich in nuclei and cellular debris Pellet rich in mitochondria (& chloroplasts in plants) Pellet rich in “microsomes” (membrane debris) Pellet rich in ribosomes 22
- 23. 2 Main Types of Cells Prokaryotic (Domains Archaea & Bacteria) Eukaryotic (Domain Eukarya) 23
- 24. 24 Basic Features of All Cells Plasma membrane Cytosol: semifluid DNA: Chromosomes carry genes Ribosomes
- 25. 25 Features of Prokaryotic Cells No nucleus DNA in nucleoid No membrane- bound organelles Cell wall, plasma membrane, & cytoplasm
- 26. Fig. 6-6 (a) A typical rod- shaped bacterium Ribosomes Plasma membrane Cell wall Capsule Flagellae Bacterial chromosome Fimbriae Nucleoid 26 Prokaryotic Cell
- 27. 27 Features of Eukaryotic Cells DNA in nucleus Nuclear envelope with pores Membrane-bound organelles Plasma membrane & cytoplasm Larger size
- 28. 28
- 29. 29
- 30. 30 Head Polar Hydrophilic Glycerol & phosphate Tails Nonpolar Hydrophobic 2 Fatty acids Phospholipid Structure
- 31. Plasma Membrane (Phospholipid bilayer) 31
- 32. Structure of the Plasma Membrane Outside of cell Inside of cell Hydrophilic region Hydrophobic region Hydrophilic region Proteins Carbohydrate side-chain 32
- 33. 33 Permeable
- 34. 34 Impermeable
- 36. 36 Surface Area- to-Volume Ratio SA divided by Volume Membrane relationship As SA doubles, volume triples Small cells have more SA relative to volume
- 37. Surface area increases while total volume remains constant 5 1 1 6 150 750 125 1251 6 61.2 Total surface area [Sum of the surface areas (height width) of all boxes sides number of boxes] Total volume [height width length number of boxes] Surface-to-volume (S-to-V) ratio [surface area ÷ volume] 37
- 38. ENDOPLASMIC RETICULUM (ER) Smooth ERRough ER Flagellum Centrosome CYTOSKELETON: Microfilaments Intermediate filaments Microtubules Microvilli Peroxisome Mitochondrion Lysosome Golgi apparatus Ribosomes Plasma membrane Nuclear envelope Nucleolus Chromatin NUCLEUS 38
- 39. 39
- 40. NUCLEUS Nuclear envelope Nucleolus Chromatin Rough endoplasmic reticulum Smooth endoplasmic reticulum Ribosomes Central vacuole Microfilaments Intermediate filaments Microtubules CYTO- SKELETON Chloroplast Plasmodesmata Wall of adjacent cell Cell wall Plasma membrane Peroxisome Mitochondrion Golgi apparatus 40
- 41. 41
- 43. 43 Nucleus Nuclear envelope with pores Nuclear lamina: protein Nuclear pores Chromatin & chromosomes
- 44. Nuclear envelope: Inner membrane Outer membrane Nuclear pore Surface of nuclear envelope 1 m 44
- 45. 45
- 46. DNA Chromatin Non-dividing cells Unorganized, loose threads of DNA & protein Chromosomes Dividing cells Genes 46
- 49. 49 Nucleolus Inside nucleus Made of RNA & protein Site of ribosomal RNA (rRNA) synthesis Makes small and large ribosomal subunits
- 50. Ribosomes Particles consisting of rRNA & proteins Made by nucleolus Small & large subunits Site of protein synthesis 50Free Ribosomes
- 54. Smooth ER Rough ER Cisternae Ribosomes Transport vesicle Transitional ER Nuclear envelope ER lumen 54
- 55. 55
- 57. 57 Rough ER Functions Contains bound ribosomes that secrete glycoproteins Makes membrane proteins Distributes transport vesicles Sends vesicles to Golgi apparatus
- 58. 58 Golgi Apparatus Cisternae: flattened membrane sacs Modifies products of the ER Makes macromolecules Sorts & packages materials into transport vesicles
- 59. 59
- 60. 60
- 61. 61 Golgi Apparatus = Amazon.com
- 62. 62
- 63. 63
- 65. Lysosomes Membrane-bound vesicles Cellular “stomachs” Contain hydrolytic enzymes that break down macromolecules 65
- 66. 66
- 68. 68 Phagocytosis
- 70. 70
- 71. Peroxisomes Smaller membrane-bound vesicles Contain enzymes that oxidize organic wastes Convert hydrogen peroxide water Break down variety of macromolecules 71
- 72. 72 Peroxisome
- 73. 73 Vacuoles Larger membrane- bound organelle derived from ER & Golgi Food vacuole: from phagocytosis Contractile vacuole: protists Central vacuole: plants
- 76. 76
- 77. 77 Mitochondria Double membrane: outer & inner Site of Aerobic cellular respiration Makes ATP In all Eukarya
- 78. 78
- 79. 79 Mitochondria Structure Smooth outer membrane Folded inner membrane = cristae Intermembrane space Matrix
- 80. Intermembrane space Outer DNA Inner membrane Cristae Matrix Free ribosomes in the mitochondrial matrix 0.1 m membrane Mitochondria Structure 80
- 81. 81 Chloroplasts In plants & protists Type of plastid Site of photosynthesis Contain chlorophyll
- 82. 82
- 83. 83
- 84. 84 Chloroplast Structure Smooth outer membrane Inner membranes = thylakoids Grana = stacks of thylakoids Stroma
- 85. Ribosomes Stroma Inner & outer membranes Granum 1 mIntermembrane space Thylakoid DNA Chloroplast Structure 85
- 86. 86 Mitochondria & Chloroplasts Similar to bacteria Have a double membrane Proteins are made by free ribosomes Have their own circular DNA molecules
- 87. – An early ancestor of eukaryotic cells engulfed a nonphotosynthetic prokaryotic cell, which formed an endosymbiont relationship with its host – The host cell and endosymbiont merged into a single organism, a eukaryotic cell with a mitochondrion – At least one of these cells may have taken up a photosynthetic prokaryote, becoming the ancestor of cells that contain chloroplasts The Endosymbiont Theory 87
- 88. NucleusEndoplasmic reticulum Nuclear envelope Ancestor of eukaryotic cells (host cell) Engulfing of oxygen- using nonphotosynthetic prokaryote, which becomes a mitochondrion Mitochondrion Nonphotosynthetic eukaryote Mitochondrion Photosynthetic eukaryote Engulfing of photosynthetic prokaryote Chloroplast 88
- 89. 89 Cytoskeleton
- 90. Functions of the Cytoskeleton Anchors organelles & organizes cell structure Supports cell & maintains cell shape Regulates cell division & biochemical activities Interacts with motor proteins to move organelles & cells 90
- 92. Microtubules 92
- 93. Microtubules Thick, hollow rods of tubulin Maintain cell shape Transport organelles & entire cell Separate chromosomes during cell division – form spindle 93
- 94. Centrosomes 94
- 95. Centrosomes Contain centrioles 9 + 0 arrangement of MT’s MT- organizing centers Create mitotic spindle 95
- 96. Centrioles 96
- 98. 98 Cilia & Flagella Both made of MT’s sheathed by plasma membrane 9 + 2 MT arrangement Anchored to cell by basal body Motor protein (dynein) drives bending movement
- 100. 100 Cilia
- 101. Flagellae101
- 103. 9+2 103
- 104. Power stroke Recovery stroke Cilia Flagellae 104
- 105. 105 Dynein “Walking” Dynein arms grab, move, & release outer MT’s Protein cross-links limit sliding MT doublets curve, bending cilium or flagellum
- 106. ATP Effect of unrestrained dynein movement 106
- 107. ATP Effect of cross-linking proteins 107
- 108. 108
- 109. 109
- 110. 110 Microfilaments
- 111. 111 Microfilaments Thin, solid protein fibers Twisted double- chain of actin Bear tension & resist pulling forces inside cell Form 3-D network (cortex) under plasma membrane
- 112. Functions of Microfilaments Support & maintain cell shape & allow changes to shape Cell motility: amoeboid movement & cytoplasmic streaming Muscle contraction Cell division 112
- 113. 113
- 116. 116
- 117. 117 Actin (with myosin motors) in muscle
- 118. 118
- 120. 120 Cell motility using actin
- 121. 100 m Cortex (outer cytoplasm): gel with actin network Inner cytoplasm: sol with actin subunits Extending pseudopodium Amoeboid movement 121
- 122. 122
- 124. Intermediate Filaments Medium-diameter keratin cables More permanent Maintain cell shape Anchor nucleus & other organelles 124
- 126. 126 Extracellular Structures Cell walls in plants Extracellular matrix of animal cells Intercellular junctions
- 127. 127
- 128. 128
- 129. 129 Cell Walls in Plants Cellulose fibers embedded with polysaccharides & proteins Protect & maintain cell shape Prevent excessive uptake of water
- 130. 130 Structure of the Plant Cell Wall Primary cell wall Middle lamella Secondary cell wall Plasmodesmata
- 131. Secondary cell wall Primary cell wall Middle lamella Central vacuole Cytosol Plasma membrane Plant cell walls Plasmodesmata 1 m 131
- 132. 132 Extracellular Matrix (ECM) of Animal Cells Made of glycoproteins: Collagen, proteoglycans, fibronectin ECM proteins bind to receptor proteins called integrins in plasma membrane
- 136. 136 Plasmodesmata
- 137. 137 Plasmodesmata
- 138. Tight junctions prevent fluid from moving across a layer of cells Tight junction Tight junction TEM 0.5 m TEM 1 m TEM 0.1 m Extracellular matrixPlasma membranes of adjacent cells Space between cells Ions or small molecules Desmosome Intermediate filaments Gap junction 138
- 139. 139 Tight Junctions
- 140. 140 Desmosomes
- 141. 141 Desmosomes
- 142. 142 Gap Junctions