1. A Tour of the Cell Ch. 4 Engineering 2 Ms. Haut

2. INTRODUCTION TO THE WORLD OF THE CELL The microscope was invented in the 17th century Using a microscope, Robert Hooke discovered cells in 1665 All living things are made of cells (cell theory) http://www.edu365.com/aulanet/comsoc/persones_t ecniques/Robert_Hooke_archivos/Robert_Hooke.jpg

3. Principles of the Cell Theory 1.All living things are made of one or more cells 2.Cells are the basic unit of structure & function in organisms 3.Cells come only from the reproduction of existing cells

4. Microscopes provide windows to the world of the cell The light microscope enables us to see the overall shape and structure of a cell Figure 4.1A Image seen by viewer Eyepiece Ocular lens Objective lens Specimen Condenser lens Light source Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings Red blood cells teaching.path.cam.ac.uk/partIB_pract/NHP1/

5. Electron microscopes Invented in the 1950s They use a beam of electrons instead of light The greater resolving power of electron microscopes –allows greater magnification –reveals cellular details websemserver.materials.ox.ac.uk/cybersem/getf...

6. Scanning electron microscope (SEM) Used to see detailed structure of cell surface Figure 4.1B Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings Red blood cells http://commons.wikimedia.org/wiki/Image:SEM_blood_ cells.jpg

7. Transmission electron microscope (TEM) Used to examine the internal structures of a cell Figure 4.1C Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings Red blood cell in capillary commons.wikimedia.org/wiki/Image:A_red_blood_...

8. Cell size and shape relate to function Figure 4.2 Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

9. At minimum, a cell must be large enough to house the parts it needs to survive and reproduce The maximum size of a cell is limited by the amount of surface needed to obtain nutrients from the environment and dispose of wastes Natural laws limit cell size

10. A small cell has a greater ratio of surface area to volume than a large cell of the same shape 30 µm10 µm Surface area of one large cube = 5,400 µm 2 Total surface area of 27 small cubes = 16,200 µm 2 Figure 4.3 Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

11. Categories of Cells Contains membranous organelles No membranous organelles DNA in a membrane bound nucleus DNA in nucleoid region (no nucleus) More complex structureSimpler structure Larger sizeSmaller size EukaryoticProkaryotic

12. Enclosed by a plasma membrane Usually encased in a rigid cell wall –The cell wall may be covered by a sticky capsule Inside the cell are its DNA and other parts Ribosomes Figure 4.4 Capsule Cell wall Plasma membrane Prokaryotic flagella Nucleoid region (DNA) Pili Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings Prokaryotes

13. All other life forms are made up of one or more eukaryotic cells These are larger and more complex than prokaryotic cells Eukaryotes are distinguished by the presence of a true nucleus Eukaryotic cells are partitioned into functional compartments

14. An animal cell Plasma membrane Figure 4.5A Golgi apparatus Ribosomes Nucleus Smooth endoplasmic reticulum Rough endoplasmic reticulum Mitochondrion Not in most plant cells Cytoskeleton Flagellum Lysosome Centriole Peroxisome Microtubule Intermediate filament Microfilament Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

15. The Plasma Membrane: A Fluid Mosaic of Lipids and Proteins The membranes of cells are composed of: Phospholipids Proteins Cholesterol Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings http://bio.winona.edu/berg/ILLUST/memb-mod.jpg

16. Plasma Membrane Phospholipids form a two-layered membrane, the phospholipid bilayer. Figure 4.7a

17. Figure 4.7b Plasma Membrane Most membranes have specific proteins embedded in the phospholipid bilayer. Proteins serve a number of functions Transport channels Enzymes

18. Plasma Membrane Cholesterol molecules help keep the membrane “fluid” at lower temperatures http://www.uic.edu/classes/bios/bios100/lectf03am/cholesterol.jpg http://sps.k12.ar.us/massengale/images/cell20membrane.jpg Cholesterol

19. Fluid Mosaic Model Fluid part of model: Membrane phospholipids and proteins can drift about in the plane of the membrane. Mosaic part of model: A diversity of molecules exists within the membrane Phospholipids Different proteins Cholesterol

20. Membranes The plasma membrane separates the living cell from its nonliving surroundings. The cytoplasm contains organelles Most organelles have membranes –These compartmentalize the interior of the cell –This allows the cell to carry out a variety of activities simultaneously

21. Plant Cells A plant cell has some structures that an animal cell lacks: –Chloroplasts –A rigid cell wall –Central vacuole –Plasmodesmata

22. The largest organelle is usually the nucleus The nucleus is separated from the cytoplasm by the nuclear envelope The nucleus is the cellular control center –It contains the DNA that directs the cell’s activities The nucleus is the cell’s genetic control center Nucleus

23. Figure 4.6 Chromatin Nucleolus Pore NUCLEUS Two membranes of nuclear envelope ROUGH ENDOPLASMIC RETICULUM Ribosomes Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

24. Many cell organelles are related through the endomembrane system The endomembrane system is a collection of membranous organelles –Organelles manufacture and distribute cell products –Divides cell into compartments

25. Rough endoplasmic reticulum The rough ER manufactures membranes Ribosomes on its surface are sites where proteins are made 1 2 3 4Transport vesicle buds off Ribosome Sugar chain Glycoprotein Secretory (glyco-) protein inside transport vesicle ROUGH ER Polypeptide Figure 4.8 Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings http://micro.magnet.fsu.edu/cells/endoplasmicreticulum/images/en doplasmicreticulumfigure1.jpg

26. Smooth endoplasmic reticulum has a variety of functions Smooth ER synthesizes lipids In some cells, it regulates carbohydrate metabolism and breaks down toxins and drugs

27. SMOOTH ER ROUGH ER Nuclear envelope Ribosomes SMOOTH ERROUGH ER Figure 4.9 Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

28. Golgi apparatus The Golgi apparatus consists of stacks of membranous sacs –These receive and modify ER products, then send them on to other organelles or to the cell membrane Figure 4.12

29. A membrane- enclosed sac budded off the Golgi –It contains digestive enzymes. –The enzymes break down macromolecules Lysosomes digest the cell’s food and wastes LYSOSOME Nucleus Figure 4.11A

30. Lysosomal enzymes digest food destroy bacteria recycle damaged organelles function in embryonic development in animals http://sun.menloschool.org/~cweaver/cells/e/lysosomes/lysozome.jpg

31. Lysosomal storage diseases are hereditary –They interfere with other cellular functions –Examples: Pompe’s disease, Tay-Sachs disease Connection: Abnormal lysosomes can cause fatal diseases

32. Peroxisomes Specialized lysosome containing catalase Produces hydrogen peroxide (H 2 O 2 ) as waste product Catalase breaks down toxic H 2 O 2 H 2 O 2 --- catalase ---> H 2 O + O 2 http://faculty.une.edu/com/abell/histo/peroxisome.jpg

33. Plant cells contain a large central vacuole –The vacuole has lysosomal and storage functions Vacuoles function in the general maintenance of the cell Central vacuole Nucleus Figure 4.13A Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

34. Contractile Vacuole Protists may have contractile vacuoles –These pump out excess water Figure 4.13B Nucleus Contractile vacuoles Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings Collapsing contractile vacuole of Protozoa www.microscopy-uk.org.uk/.../vidjuna.html

35. The various organelles of the endomembrane system are interconnected structurally and functionally A review of the endomembrane system Transport vesicle from ER Rough ER Transport vesicle from Golgi Plasma membrane Vacuole Lysosome Golgi apparatus Nuclear envelope Smooth ER Nucleus Figure 4.14 Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

37. ENERGY-CONVERTING ORGANELLES Chloroplasts Mitochondria

38. Chloroplasts Chloroplasts are found in plants and some protists Chloroplasts convert solar energy to chemical energy in sugars Figure 4.16

39. Mitochondria Mitochondria carry out cellular respiration –This process uses the chemical energy in food to make ATP for cellular work Figure 4.17

40. Endosymbiosis –Mitochondria and chloroplasts each contain their own DNA separate from the nucleus. –Evidence for Endosymbiosis theory Mitochondria and chloroplasts evolved from free-living prokaryotes in the distant past. http://faculty.ircc.edu/faculty/tfischer/images/endosymbiosis.jpg

41. A network of protein fibers makes up the cytoskeleton The cell’s internal skeleton helps organize its structure and activities THE CYTOSKELETON AND RELATED STRUCTURES Figure 4.17A Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

42. Microfilaments of actin enable cells to change shape and move Intermediate filaments reinforce the cell and anchor certain organelles Microtubules –give the cell rigidity –provide anchors for organelles –act as tracks for organelle movement 3 Types of fibers make up the cytoskeleton

43. Figure 4.17B MICROFILAMENT INTERMEDIATE FILAMENT MICROTUBULE Actin subunitFibrous subunits Tubulin subunit 7 nm10 nm 25 nm Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

44. Cilia and flagella move when microtubules bend Eukaryotic cilia and flagella are locomotor appendages that protrude from certain cells A cilia or flagellum is composed of a core of microtubules wrapped in an extension of the plasma membrane www.cco.caltech.edu/~brokawc/Dem o1/BeadExpt.html http://fig.cox.miami.edu/~cmallery/150/cells/centriole.jpg http://www.microscopy- uk.org.uk/mag/imgjan99/janvid2.gif

45. FLAGELLUM Outer microtubule doublet Plasma membrane Central microtubules Outer microtubule doublet Plasma membrane Electron micrograph of sections: Flagellum Basal body Basal body (structurally identical to centriole) Figure 4.18A Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

46. Clusters of microtubules drive the whipping action of these organelles Figure 4.18B Microtubule doublet Dynein arm Sliding force Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

47. Cells interact with their environments and each other through their surfaces Plant cells are supported by rigid cell walls made largely of cellulose –They connect by plasmodesmata, channels that allow them to share water, food, and chemical messages Cell surfaces protect, support, and join cells EUKARYOTIC CELL SURFACES AND JUNCTIONS

48. Figure 4.19A Vacuole Layers of one plant cell wall Walls of two adjacent plant cells PLASMODESMATA Cytoplasm Plasma membrane Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

49. Animal cells are embedded in an extracellular matrix It is a sticky layer of glycoproteins It binds cells together in tissues It can also have protective and supportive functions http://kentsimmons.uwinnipeg.ca/cm1504/Image122.gif

50. Tight junctions can bind cells together into leakproof sheets Anchoring junctions link animal cells Communicating junctions allow substances to flow from cell to cell TIGHT JUNCTION ANCHORING JUNCTION COMMUNICATING JUNCTION Plasma membranes of adjacent cells Extracellular matrix Figure 4.19B Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

51. Eukaryotic organelles fall into four functional groups Eukaryotic organelles comprise four functional categories Table 4.20 Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

52. Table 4.20 (continued) Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

53. It is almost certain that Earth is the only life- bearing planet in our solar system But it is conceivable that conditions on some of the moons of the outer planets or on planets in other solar systems have allowed the evolution of life Connection: Extraterrestrial life-forms may share features with life on Earth Figure 4.21 Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

54. Acknowledgements Essential Biology with Physiology, 2 nd ed., by Campbell, Reece, and Simon, ©2007. These images have been produced from the originals by permission of the publisher. These illustrations may not be reproduced in any format for any purpose without express written permission from the publisher. BIOLOGY: CONCEPTS AND CONNECTIONS 4th Edition, by Campbell, Reece, Mitchell, and Taylor, ©2003. These images have been produced from the originals by permission of the publisher. These illustrations may not be reproduced in any format for any purpose without express written permission from the publisher. Background image found at http://www.paxcam.com/imgs/library/2/thumbnails/slide_19.jpg http://www.paxcam.com/imgs/library/2/thumbnails/slide_19.jpg