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Bio201chapter4powerpoint 150914185916-lva1-app6892
- 1. Chapter 04 Lecture Outline Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1
- 3. 3 Cells • Cells were discovered in 1665 by Robert Hooke • Early studies of cells were conducted by – Mathias Schleiden (1838) – Theodor Schwann (1839) • Schleiden and Schwann proposed the Cell Theory
- 4. 4 Cell Theory 1. All organisms are composed of cells 2. Cells are the smallest living things 3. Cells arise only from pre-existing cells • All cells today represent a continuous line of descent from the first living cells
- 5. 5 Cell size is limited • Most cells are relatively small due reliance on diffusion of substances in and out of cells • Rate of diffusion affected by – Surface area available – Temperature – Concentration gradient – Distance
- 6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4– 3 πr3 ) 3 Cell radius (r) Surface Area / Volume Surace area (4πr2 ) Volume ( 4.189 unit3 12.57 unit2 1 unit 10 unit 1257 unit2 4189 unit3 0.3
- 7. Surface area-to-volume ratio • Organism made of many small cells has an advantage over an organism composed of fewer, larger cells • As a cell’s size increases, its volume increases much more rapidly than its surface area • Some cells overcome limitation by being long and skinny – like neurons 7
- 8. 8 Microscopes • Not many cells are visible to the naked eye – Most are less than 50 μm in diameter • Resolution – minimum distance two points can be apart and still be distinguished as two separate points – Objects must be 100 μm apart for naked eye to resolve them as two objects rather than one
- 9. 2 types • Light microscopes – Use magnifying lenses with visible light – Resolve structures that are 200 nm apart – Limit to resolution using light • Electron microscopes – Use beam of electrons – Resolve structures that are 0.2 nm apart 9
- 10. • Electron microscopes – Transmission electron microscopes transmit electrons through the material – Scanning electron microscopes beam electrons onto the specimen surface 10 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. HumanEye LightMicroscope ElectronMicroscope Hydrogen atom Amino acid Logarithmic scale Protein Ribosome Large virus (HIV) Human red blood cell Prokaryote Human egg Paramecium Chicken egg Adult human Frog egg Chloroplast Mitochondrion 1 m 10 cm 1 cm 1 mm 1 nm 0.1 nm (1 Å) 10 nm 100 nm 1 µm 10 µm 100 µm 10 m 100 m
- 11. 11 Basic structural similarities 1. Nucleoid or nucleus where DNA is located 2. Cytoplasm – Semifluid matrix of organelles and cytosol 3. Ribosomes – Synthesize proteins 4. Plasma membrane – Phospholipid bilayer
- 12. 12 Prokaryotic Cells • Simplest organisms • Lack a membrane-bound nucleus – DNA is present in the nucleoid • Cell wall outside of plasma membrane • Do contain ribosomes (not membrane- bound organelles) • Two domains of prokaryotes – Archaea – Bacteria
- 13. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cytoplasm Ribosomes Nucleoid (DNA) Plasma membrane Capsule Cell wall Pili Flagellum Pilus 0.3 µm © Phototake
- 14. Bacterial cell walls • Most bacterial cells are encased by a strong cell wall – composed of peptidoglycan – Cell walls of plants, fungi, and most protists different • Protect the cell, maintain its shape, and prevent excessive uptake or loss of water • Susceptibility of bacteria to antibiotics often depends on the structure of their cell walls • Archaea lack peptidoglycan 14
- 15. 15 Flagella • Present in some prokaryotic cells – May be one or more or none • Used for locomotion • Rotary motion propels the cell
- 16. 16 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Outer protein ring Hook Filament Inner protein ring H+ H+ Peptidoglycan portion of cell wall Outer membrane Plasma membrane a. b. c. 0.5 µm a: © Eye of Science/Photo Researchers, Inc.
- 17. 17 Eukaryotic Cells • Possess a membrane-bound nucleus • More complex than prokaryotic cells • Hallmark is compartmentalization – Achieved through use of membrane-bound organelles and endomembrane system • Possess a cytoskeleton for support and to maintain cellular structure
- 18. 18 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nucleus Nucleolus Nuclear pore Intermediate filament Ribosomes Ribosomes Cytoplasm Cytoskeleton Microtubule Centriole Plasma membrane Mitochondrion Golgi apparatus Exocytosis Peroxisome Smooth endoplasmic reticulum Rough endoplasmic reticulum Microvilli Nuclear envelope Actin filament (microfilament) Intermediate filament Lysosome Vesicle
- 19. 19 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nucleus Nucleolus Nuclear pore Intermediate filament Ribosome Cytoplasm Cytoskeleton Microtubule Plasma membrane Mitochondrion Peroxisome Smooth endoplasmic reticulum Rough endoplasmic reticulum Nuclear envelope Central vacuole Plasmodesmata Adjacent cell wall Cell wall Chloroplast Golgi apparatus Vesicle Actin filament (microfilament) Intermediate filament
- 20. 20 Nucleus • Repository of the genetic information • Most eukaryotic cells possess a single nucleus • Nucleolus – region where ribosomal RNA synthesis takes place • Nuclear envelope – 2 phospholipid bilayers – Nuclear pores – control passage in and out • In eukaryotes, the DNA is divided into multiple linear chromosomes – Chromatin is chromosomes plus protein
- 21. 21 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nuclear basket Nuclear pores Nuclear envelope Nucleolus Chromatin Nucleoplasm Nuclear lamina Inner membrane Outer membrane Cytoplasmic filaments Nuclear pore a.
- 22. Ribosomes • Cell’s protein synthesis machinery • Found in all cell types in all 3 domains • Ribosomal RNA (rRNA)-protein complex • Protein synthesis also requires messenger RNA (mRNA) and transfer RNA (tRNA) • Ribosomes may be free in cytoplasm or associated with internal membranes 22
- 23. 23 Endomembrane System • Series of membranes throughout the cytoplasm • Divides cell into compartments where different cellular functions occur • One of the fundamental distinctions between eukaryotes and prokaryotes
- 24. 24 Endoplasmic reticulum • Rough endoplasmic reticulum (RER) – Attachment of ribosomes to the membrane gives a rough appearance – Synthesis of proteins to be secreted, sent to lysosomes or plasma membrane • Smooth endoplasmic reticulum (SER) – Relatively few bound ribosomes – Variety of functions – synthesis, store Ca2+ , detoxification • Ratio of RER to SER depends on cell’s function
- 25. 25 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ribosomes Smooth endoplasmic reticulum Smooth endoplasmic reticulum 0.08 µm (inset): © Dr. Donald Fawcett & R. Bolender/Visuals Unlimited Rough endoplasmic reticulum Rough endoplasmic reticulum
- 26. 26 Golgi apparatus • Flattened stacks of interconnected membranes (Golgi bodies) • Functions in packaging and distribution of molecules synthesized at one location and used at another within the cell or even outside of it • Has cis and trans faces • Vesicles transport molecules to destination
- 27. 27 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 µm Secretory vesicle Forming vesicle trans face cis face Fusing vesicle Transport vesicle (inset): © Dennis Kunkel/Phototake
- 28. 28 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1. 2. 3. Golgi membrane protein Cisternae Secretory vesicle Cell membrane Extracellular fluid Rough endoplasmic reticulum Membrane protein Newly synthesized protein Vesicle containing proteins buds from the rough endo- plasmic reticulum, diffuses through the cell, and fuses to the cis face of the Golgi apparatus. Smooth endoplasmic reticulumcis face Golgi Apparatus trans face The proteins are modified and packaged into vesicles for transport. Secreted protein The vesicle may travel to the plasma membrane, releasing its contents to the extracellular environment. Transport vesicle Nucleus Nuclear pore Ribosome Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 29. 29 Lysosomes • Membrane-bounded digestive vesicles • Arise from Golgi apparatus • Enzymes catalyze breakdown of macromolecules • Destroy cells or foreign matter that the cell has engulfed by phagocytosis
- 30. 30 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lysosome aiding in the breakdown of an old organelle Lysosome aiding in the digestion of phagocytized particles Golgi membrane protein Cisternae Rough endoplasmic reticulum Smooth endoplasmic reticulum cis face Golgi Apparatustrans face Nucleus Ribosome Membrane protein Hydrolytic enzyme Transport vesicle Breakdown of organelle Lysosome Lysosome Digestion Old or damaged organelle Food vesicle Phagocytosis Nuclear pore
- 31. Microbodies • Variety of enzyme- bearing, membrane- enclosed vesicles • Peroxisomes – Contain enzymes involved in the oxidation of fatty acids – Hydrogen peroxide produced as by- product – rendered harmless by catalase 31 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 0.2 µm (inset): From S.E. Frederick and E.H. Newcomb, “Microbody-like organelles in leaf cells,” Science, 163:1353-5. © 21 March 1969. Reprinted with permission from AAAS
- 32. 32 Vacuoles • Membrane-bounded structures in plants • Various functions depending on the cell type • There are different types of vacuoles: – Central vacuole in plant cells – Contractile vacuole of some fungi and protists – Storage vacuoles
- 33. 33 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (inset): © Henry Aldrich/Visuals Unlimited Nucleus Chloroplast Tonoplast Central vacuole 1.5 µm Cell wall
- 34. 34 Mitochondria • Found in all types of eukaryotic cells • Bound by membranes – Outer membrane – Intermembrane space – Inner membrane has cristae – Matrix • On the surface of the inner membrane, and also embedded within it, are proteins that carry out oxidative metabolism • Have their own DNA
- 35. 35 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Intermembrane space Inner membrane Outer membrane Ribosome Matrix DNA Crista 0.2 µm (inset): © Dr. Donald Fawcett & Dr. Porter/Visuals Unlimited
- 36. 36 Chloroplasts • Organelles present in cells of plants and some other eukaryotes • Contain chlorophyll for photosynthesis • Surrounded by 2 membranes • Thylakoids are membranous sacs within the inner membrane – Grana are stacks of thylakoids • Have their own DNA
- 37. 37 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ribosome DNA Stroma Stroma Thylakoid membrane Outer membrane Inner membrane Thylakoid disk Granum Granum 1.5 µm (inset): © Dr. Jeremy Burgess/Photo Researchers, Inc.
- 38. 38 Endosymbiosis • Proposes that some of today’s eukaryotic organelles evolved by a symbiosis arising between two cells that were each free- living • One cell, a prokaryote, was engulfed by and became part of another cell, which was the precursor of modern eukaryotes • Mitochondria and chloroplasts
- 39. 39 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chloroplast Chloroplast Modern Eukaryote Unknown Bacterium Unknown Archaeon Mitochondrion Protobacterium Modern EukaryoteCyanobacterium Cyanobacterium Unknown Archaeon Protobacterium Mitochondrion Nucleus Nucleus
- 40. 40 Cytoskeleton • Network of protein fibers found in all eukaryotic cells – Supports the shape of the cell – Keeps organelles in fixed locations • Dynamic system – constantly forming and disassembling
- 41. 41 3 types of fibers • Microfilaments (actin filaments) – Two protein chains loosely twined together – Movements like contraction, crawling, “pinching” • Microtubules – Largest of the cytoskeletal elements – Dimers of α- and β-tubulin subunits – Facilitate movement of cell and materials within cell • Intermediate filaments – Between the size of actin filaments and microtubules – Very stable – usually not broken down
- 42. 42 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Microtubule Intermediate filament Actin filament Cell membrane a. Actin filaments b. Microtubules c. Intermediate filament
- 43. Centrosomes • Region surrounding centrioles in almost all animal cells • Microtubule-organizing center – Can nucleate the assembly of microtubules • Animal cells and most protists have centrioles – pair of organelles • Plants and fungi usually lack centrioles 43
- 44. Centrioles 44 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Microtubule triplet
- 45. 45 Cell Movement • Essentially all cell motion is tied to the movement of actin filaments, microtubules, or both • Some cells crawl using actin microfilaments • Flagella and cilia have 9 + 2 arrangement of microtubules – Not like prokaryotic flagella – Cilia are shorter and more numerous
- 46. 46 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Flagellum Basal body Microtubule triplet Central microtubule pair Plasma membrane Radial spoke Dynein arm Doublet microtubule 0.1 µm 0.1 µm (top & bottom insets): © William Dentler, University of Kansas
- 47. • Eukaryotic cell walls – Plants, fungi, and many protists – Different from prokaryote – Plants and protists – cellulose – Fungi – chitin – Plants – primary and secondary cell walls 47 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Plant cell Plasmodesmata Primary wall Secondary wall Cell 1 Cell 2 Primary wall Secondary wall Plasma membrane Middle lamella Middle lamella Plasma membrane © Biophoto Associates/Photo Researchers, Inc. 0.4 µm
- 48. 48 Extracellular matrix (ECM) • Animal cells lack cell walls • Secrete an elaborate mixture of glycoproteins into the space around them • Collagen may be abundant • Form a protective layer over the cell surface • Integrins link ECM to cell’s cytoskeleton – Influence cell behavior
- 49. 49 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cytoplasm Actin filament Integrin Fibronectin Collagen Elastin Proteoglycan
- 50. 50
- 51. Cell-to-cell interactions • Surface proteins give cells identity – Cells make contact, “read” each other, and react – Glycolipids – most tissue-specific cell surface markers – MHC proteins – recognition of “self” and “nonself” cells by the immune system 51
- 52. Cell connections • 3 categories based on function 1.Tight junction – Connect the plasma membranes of adjacent cells in a sheet – no leakage 2.Anchoring junction – Mechanically attaches cytoskeletons of neighboring cells (desmosomes) 3.Communicating junction – Chemical or electrical signal passes directly from one cell to an adjacent one (gap junction, plasmodesmata) 52
- 53. 53 a. Tight junction Adjacent plasma membranes Tight junction proteins Intercellular space Microvilli Basal lamina Adhesive junction (desmosome) Tight junction Intermediate filament Communicating junction 2.5 µm Intercellular space b. Adjacent plasma membranes Cadherin Cytoplasmic protein plaque Cytoskeletal filaments anchored to plaque Anchoring junction (desmosome) 0.1 µm c. Intercellular space Channel (diameter 1.5 nm) Communicating junction Connexon Two adjacent connexons forming an open channel between cells Adjacent plasma membranes 1.4 µm Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: Courtesy of Daniel Goodenough; b: © Dr. Donald Fawcett/Visuals Unlimited; c: © Dr. Donald Fawcett/D. Albertini/Visuals Unlimited
- 54. Plasmodesmata 54 •Plant cells • Plasmodesmata • Specialized openings in their cell walls • Cytoplasm of adjoining cells are connected • Function similar to gap junctions in animal cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Primary Cell wall Middle lamella Plasma membrane Plasmodesma Smooth ER Central tubule Cell 2Cell 1