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CHAPTER 3

CHAPTER 3. A TOUR OF THE CELL. ALL ORGANISMS ARE MADE OF CELLS. THE CELL THEORY :. 1. All living things are composed of cells. 2. Cells are the basic unit of structure and function in living things. 3. All cells come from pre-existing cells. TYPES OF MICROSCOPES.

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CHAPTER 3

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  1. CHAPTER 3 A TOUR OF THE CELL

  2. ALL ORGANISMS ARE MADE OF CELLS

  3. THE CELL THEORY: 1. All living things are composed of cells. 2. Cells are the basic unit of structure and function in living things. 3. All cells come from pre-existing cells.

  4. TYPES OF MICROSCOPES • Light Microscopes: • Use visible light • Used to examine living cells • Magnify about 1000 times • Not powerful enough to view internal cell structures

  5. Light Microscope

  6. TYPES OF MICROSCOPES: • Electron Microscopes: • Electron beams used for magnification • Specimens must be killed and placed in a vacuum to be viewed • Magnify up to a million times • SEM used to view cell surface • TEM used to view internal structures

  7. Electron Microscope

  8. Electron Micrograph Jumping spider foot

  9. PROKARYOTIC CELLS • Most primitive cell type • Lack internal membrane-bound structures—organelles—that perform specific functions • First organisms to appear in fossil record • Include organisms from the Domains Archaea and Bacteria

  10. Prokaryotic Cell

  11. EUKARYOTIC CELLS • More advanced cell type • Cells contain membrane-bound structures called organelles—including a nucleus—that perform specific functions • Domain Eukarya • Includes the Kingdoms Plantae, Animalia, Protista, and Fungi

  12. Eukaryotic Cells Human cells: Tissue

  13. PROKARYOTIC vs. EUKARYOTIC

  14. Prokaryotic Cell:

  15. PLANT vs. ANIMAL CELLS • Both contain most organelles • Plant cells have 3 structures not seen in animal cells: 1. Cell wall: surrounds cell membrane 2. Chloroplast: photosynthesis occurs here 3. Central vacuole: large storage area

  16. Animal Cell

  17. Plant Cell

  18. THE CELL BUILDS A DIVERSITY OF PRODUCTS

  19. NUCLEUS • Directs the activities of the cell • Contains most of cell’s DNA • Chromatin: long fibers of DNA; - attached to proteins - organized when cell divides

  20. NUCLEUS • Nuclear envelope: pair of membranes surrounding nucleus - has tiny holes or pores—substances made in the nucleus exit through these pores

  21. NUCLEUS • Nucleolus: round structure made of fibers and granules inside nucleus - produces ribosomes—small organelles involved in protein synthesis - not surrounded by membranes

  22. RIBOSOMES • Made of proteins and nucleic acids • Produce all the proteins for the cell • Float free in cytoplasm or are attached to membrane network within the cytoplasm

  23. NUCLEUS

  24. ENDOPLASMIC RETICULUM • Network of membranes within cytoplasm • Connected to the nucleus • One of the main manufacturing and transportation facilities of the cell • Two distinct regions: 1. Rough ER 2. Smooth ER

  25. ROUGH ER • Has ribosomes attached • Ribosomes produce proteins and insert them into or through ER membrane • Some proteins produced are packaged in vesicles and exported • Cells that secrete many proteins are rich in rough ER

  26. SMOOTH ER • No attached ribosomes • Produce lipid molecules • Cells of ovaries and testes that produce sex hormones (cholesterol derivatives) are rich in smooth ER

  27. ENDOPLASMIC RETICULUM

  28. GOLGI APPARATUS • Series of flattened sacs that receives chemical products in vesicles • Modifies, stores, and repackages cell products in vesicles • Routes repackaged vesicles with chemical products to their destinations

  29. GOLGI APPARATUS Note vesicles forming and leaving Golgi apparatus

  30. VACUOLES • Membrane-bound sacs that serve as storage areas • Many store undigested nutrients • Function varies from organism to organism

  31. CONTRACTILE VACUOLES • Found in some unicellular freshwater organisms Fig 6-22a; p. 126 • Pumps out excess water that diffuses into the cell

  32. CENTRAL VACUOLE • Many plant cells • Contributes to growth by absorbing water and causing cells to expand • Contain pigments in flower cells that attract insects

  33. Plant Cell

  34. LYSOSOMES • Membrane-bound sacs containing digestive enzymes—several functions • Fuse with food vacuoles exposing nutrients to enzymes that digest them • Can digest harmful bacteria—in white blood cells, lysosomes release enzymes into vacuoles containing bacteria • Recycling centers for damaged organelles

  35. LYSOSOMES

  36. CHLOROPLASTS AND MITOCHONDRIA ENERGIZE CELLS

  37. CHLOROPLASTS • Most living organisms run on energy provided by photosynthesis • Photosynthesis: process of converting light energy to chemical energy • Chloroplasts: organelle found in cells of plants and algae where photosynthesis occurs

  38. Plant Cell

  39. CHLOROPLAST STRUCTURE • Enclosed by two membranes • Inner membrane divides chloroplast into compartments • One compartment is fluid-filled—stroma • Other compartment contains membrane-bound disks—thylakoids—that trap light energy and convert it to chemical energy

  40. CHLOROPLAST STRUCTURE

  41. CELLULAR RESPIRATION • Cellular respiration: process organisms access energy needed for life activities • Releases energy from food (sugars and other organic molecules) and uses it to form another organic molecule—ATP • ATP (adenosine triphosphate): main energy molecule used by cells

  42. MITOCHONDRIA • “Powerhouse of the cell”: site of cellular respiration—ATP production • Found in almost all eukaryotic cells—unlike chloroplasts which are found only in plants • Cells that are especially active, e.g. muscle cells have an abundance of mitochondria

  43. STRUCTURE OF MITOCHONDRIA • Enclosed by two membranes • Inner membrane—cellular respiration occurs here—has many folds • Folds increase surface area of membrane, thereby increasing number of sites where cellular respiration can occur

  44. MITOCHONDRIA Note highly folded inner membrane

  45. AN INTERNAL SKELETON SUPPORTS THE CELL AND ENABLES MOVEMENT

  46. CYTOSKELETON • Network of protein fibers extend throughout the cell • Structural pattern changes constantly • Made up of two types of fiber—microtubules and microfilaments

  47. MICROTUBULES • Straight, hollow tubes of proteins • Give rigidity and shape to cell • Provide “tracks” along which other organelles can move

  48. MICROFILAMENTS • Thinner, solid rods made of protein • Enable cell to move or change shape • Contribute to oozing movements of some cells—amoeba and white blood cells

  49. MICROTUBULE STRUCTURE

  50. FLAGELLA • Long, thin, whip-like structures projecting from cell • Wave in “S” shaped motion—enable some cells to move—e.g. sperm • Made up of microtubules

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