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Chapter 7: Cell Structure and Function

Chapter 7: Cell Structure and Function. Robert Hooke (1635-1703). English Scientist First to use the microscope to observe cells Coined the term “cell” Looked at cork cells. Anton van Leeuwenhoek 1632-1723. Dutch scientist Invented the first compound microscope

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Chapter 7: Cell Structure and Function

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  1. Chapter 7: Cell Structure and Function

  2. Robert Hooke (1635-1703) • English Scientist • First to use the microscope to observe cells • Coined the term “cell” • Looked at cork cells

  3. Anton van Leeuwenhoek1632-1723 • Dutch scientist • Invented the first compound microscope • First to observe LIVING cells • Blood cells and protists

  4. Robert Brown1773-1858 • Scottish botanist • In 1831 he was the first person to observe the nucleus of a cell

  5. Schleiden & Schwann1804-1881 1810-1882

  6. Schleiden Said “all plants are made up of cells” Schwann Said “all animals are made up of cells” Developing Cell Theory 1838

  7. Coined the term “protoplasm” to refer to the jellylike material that fills the cell. Said “all cells arise only from preexisting cells” Johannes RudolphPurkinje Virchow

  8. Cell Theory Overview • All organisms are made of one or more cells. • All cells carry on life activities. • New cells arise only from other living cells.

  9. PROKARYOTIC Simplest form Lack membrane bound structures Example: bacteria and some protists EUKARYOTIC Most common Possess membrane bound structures and a nucleus Found in most living things Prokaryotic vs Eukaryotic

  10. Sizes of Cells • Eukaryotic are usually larger than prokaryotic • Both nutrients and wastes are constantly entering and exiting cells • Vary in size and shape

  11. Cell Structures and Organelles Organelles = specialized internal structures of eukaryotic cells

  12. CELL WALL • Found in most bacteria and all plant cells • Gives cell its shape and provides protection • Allows passage of materials • In plant cells, it is made of cellulose • http://www.cellsalive.com/

  13. THE NUCLEUS • Control center or “ city hall ” of cell. • Largest organelle • Controls metabolism and cell reproduction

  14. Structure of nucleus • Nuclear envelope = membrane that surrounds the nucleus that acts in manner similar to the cell membrane • Nucleolus = dense are in center of nucleus where DNA,RNA, and proteins are found. *site where ribosomes are produced

  15. Picture of nucleus:

  16. MICROFILAMENTS • Long, solid, threadlike structures • Made of actin • Involved in muscle contraction and cyclosis • Movement of cytoplasm

  17. MICROTUBULES • Hollow, cylindrical structures • Helps to give cell its shape • Made of tubulin • Involved in mitosis • More information

  18. Cytoplasm • Watery material lying within the cell between the cell membrane and the nucleus • Formally called the protoplasm by Purkinje • Contains all the other organelles

  19. RIBOSOMES • Very small • “mini factories” of the cell • Responsible for protein synthesis with the help of RNA • Examples: John Morrell, Gateway

  20. ENDOPLASMIC RETICULUM (ER) • Fluid filled canals • Continuous paths for transport of materials • Divides the cell into compartments

  21. ER continued • Acts as a “street system” in a city or conveyer at a factory • Rough ER = surface lined with ribosomes • Smooth ER = no ribosomes

  22. GOLGI BODIES • Packaging, storage and processing of proteins • “ Post Office ” of the cell • Protein arrives from the ER to be packaged in vesicles.

  23. ER, Ribosome, & Golgi

  24. LYSOSOMES • Many strong digestive enzymes • Produced by Golgi Bodies • Involved in digestion of food in the cell • Helps break down worn out organelles and wastes • “ Garbage Truck ” • Recycles cell materials

  25. VACUOLES • Found mainly in plants but a few are found in animal cells • Many different types • Examples: Food and contractile • Act as a storage unit

  26. Contractile vacuoles • Location in plant cells where excess water collects

  27. Chloroplasts • A special type of chromoplast that contains chlorophyll • Most important • Contains grana and stroma • Contain their own DNA • Site of photosynthesis

  28. Chloroplast Structure

  29. MITOCHONDRIA • Release energy used by the cell • “power plant” • Double membrane for extra surface area • Responsible for cellular respiration • Process by which energy is released using oxygen

  30. Mitochondria structure

  31. Mitochondria (powerhouse) • Act similar to electric power plant • Upto 300 to 800 per cell • What advantage is their to having its own DNA? • Can replicate itself

  32. Organelle DNA • The only two organelles that contain their own DNA are mitochondria and chloroplasts • In animals, all of an organisms organelle DNA is maternal in origin. • Why?

  33. CELL MEMBRANE • Controls what materials move in and out • Helps to maintain homeostasis • Similar to the “city limits” • Made up of three substances : • Lipids, proteins, and carbohydrates

  34. Fluid-Mosaic Model

  35. Protein functions • Transport proteins = control movement of materials. • Receptors = act to signal cell when to begin or stop metabolizing. • Enzymes = start chemical rxns. • Binding site for internal structures.

  36. Selectively permeable Some substances pass through while others may not. Regulates chemical composition Maintains homeostasis

  37. Diffusion • Movement of molecules from a region of high concentration to a region of low concentration

  38. Osmosis • Diffusion of WATER across a selectively permeable membrane from a region of high water concentration to a region of low water concentration. • Osmotic pressure = • Increased pressure resulting from osmosis

  39. Isotonic solution • Same concentration of dissolved substances in solution as there is in the cell • Same water concentrations • Net result • No net gain or loss of water

  40. Hypotonic solution • Lower concentration of dissolved substances in solution than in the cell • More water outside the cell than inside the cell • Net result :

  41. Hypertonic pressure • A high concentration of dissolved substances outside the cell • More water in the cell than outside the cell • Net result :

  42. Facilitated diffusion No energy needed Concentration gradient determines movement Uses protein channels ACTIVE Usually works against the conc. Gradient Often a transport protein helps the movement (ATP) Facilitated diffusion vs Active transport

  43. Sodium-potassium pump

  44. Endocytosis • Transport of material into the cell by means of a vesicle • Pinocytosis = small amounts of liquid engulfed • Phagocytosis = small amounts of solid ingested

  45. Exocytosis • Transport of material out of the cell by means of a vesicle • Exocytosis movie

  46. Cellular organization • Simplest form of life: unicellular Ex. bacteria, protists, algae • Multicellular: • The simplest form is that of a colony • Little if any cellular specialization • Example: Volvox (algae)

  47. Organization CELLS TISSUES ORGAN SYSTEM ORGANS ORGANISM

  48. Tissues: • A group of cells which are structurally similar and perform the same function.

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