3. cellular basis of life


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3. cellular basis of life

  1. 2. Do you know that…. <ul><li>The average human being is composed of around 100 Trillion individual cells!!! </li></ul><ul><li>Each cell has about 10,000 times as many molecules as the Milky Way has stars </li></ul><ul><li>Three-hundred-million cells die in the human body every minute </li></ul>
  2. 3. Discovery of Cells <ul><li>1665- English Scientist, Robert Hooke , discovered cells while looking at a thin slice of cork. </li></ul><ul><li>He described the cells as tiny boxes or a honeycomb </li></ul><ul><li>He thought that cells only existed in plants and fungi </li></ul>
  3. 4. Anton van Leuwenhoek <ul><li>1673- Used a handmade microscope to observe pond scum & discovered single-celled organisms </li></ul><ul><li>He called them “animalcules” </li></ul><ul><li>He also observed blood cells from fish, birds, frogs, dogs, and humans </li></ul><ul><li>Therefore, it was known that cells are found in animals as well as plants </li></ul><ul><li>Father of Microscopy </li></ul>
  4. 5. Development of Cell Theory <ul><li>1838- German Botanist, Matthias Schleiden , concluded that all plant parts are made of cells </li></ul><ul><li>1839- German physiologist, Theodor Schwann , who was a close friend of Schleiden, stated that all animal tissues are composed of cells. </li></ul>
  5. 6. Development of Cell Theory <ul><li>1858- Rudolf Virchow , German physician, after extensive study of cellular pathology, concluded that cells must arise from preexisting cells. </li></ul>
  6. 7. <ul><li>1. All organisms are composed of one or more cells. (Schleiden & Schwann)(1838-39) </li></ul><ul><li>2. The cell is the basic unit of life in all living things. (Schleiden & Schwann)(1838-39) </li></ul><ul><li>3. All cells are produced by the division of preexisting cells. (Virchow)(1858) </li></ul>The 3 Basic Components of the Cell Theory
  7. 8. Modern Cell Theory <ul><li>Modern Cell Theory contains 4 statements, in addition to the original Cell Theory: </li></ul><ul><li>The cell contains hereditary information(DNA) which is passed on from cell to cell during cell division. </li></ul><ul><li>All cells are basically the same in chemical composition and metabolic activities. </li></ul>
  8. 9. Modern Cell Theory 3. All basic chemical & physiological functions are carried out inside the cells.(movement, digestion,etc) 4. Cell activity depends on the activities of sub-cellular structures within the cell(organelles, nucleus, plasma membrane)
  9. 10. Modern Microscopes <ul><ul><li>Types </li></ul></ul><ul><ul><ul><li>Light microscope (400-1000X) </li></ul></ul></ul><ul><ul><ul><li>Confocal/Fluorescence microscope (500X) </li></ul></ul></ul><ul><ul><ul><li>Electron microscope (1000-10000X) </li></ul></ul></ul>
  10. 11. MICROSCOPE
  11. 12. The light microscope enables us to see the overall shape and structure of a cell
  12. 13. <ul><li>combined the laser scanning method with the 3D detection of biological objects labeled with fluorescent markers </li></ul><ul><li>achieves a controlled and highly limited depth of focus </li></ul>Confocal/Fluorescence microscope
  13. 14. Scanning electron microscope (SEM) <ul><li>They use a beam of electrons instead of light </li></ul><ul><ul><li>allows greater magnification </li></ul></ul><ul><ul><li>reveals cellular details </li></ul></ul>-produces an image of the 3D structure of the surface of a specimen Transmission electron microscope (TEM)
  15. 16. Two Fundamentally Different Types of Cells
  16. 17. The PRESENCE OR ABSENCE of a NUCLEUS is important for Classifying Cells.
  17. 18. Prokaryotes – Domain Bacteria -> Single cell organisms -> No nucleus, no compartments -> Peptidoglycan cell walls -> Binary fission -> For energy, use organic chemicals, inorganic chemicals, or photosynthesis
  18. 19. <ul><li>-> Lack peptidoglycan </li></ul><ul><li>-> Live in extreme environments </li></ul><ul><li>Include: </li></ul><ul><ul><li>Methanogens </li></ul></ul><ul><ul><li>Extreme halophiles </li></ul></ul><ul><ul><li>Extreme thermophiles </li></ul></ul><ul><li>-> Role in disease not well understood—this group has only recently been discovered </li></ul>Prokaryotes – Domain Archea
  19. 20. Eukaryotes
  20. 21. <ul><li>Structural Differences </li></ul><ul><ul><li>Plants have choloroplasts, a large central vacuole and a cell wall </li></ul></ul><ul><ul><li>Plant cells do not have centrioles </li></ul></ul><ul><ul><li>Plant cells have plasmodesmata </li></ul></ul><ul><ul><li>Animal cells have gap junctions </li></ul></ul><ul><li>Physiological Differences </li></ul><ul><ul><li>Plant cells have photosynthesis in addition to respiration </li></ul></ul><ul><ul><li>During mitosis a cell plate is formed in plant cells </li></ul></ul><ul><ul><li>Starch is molecule for energy storage while in animal cells it is glycogen </li></ul></ul><ul><ul><li>Large central vacuole stores more water and carbohydrates then animal cell vacuoles </li></ul></ul>
  21. 22. Different Cell Parts In cells, various specialized functions occur in specific places. These places are called organelles  (small organs)
  22. 23. Plasma Membrane FLUID MOSAIC MODEL
  23. 24. <ul><li>Cell membrane separates living cell from nonliving surroundings </li></ul><ul><ul><li>thin barrier = 8nm thick </li></ul></ul><ul><li>Controls traffic in & out of the cell </li></ul><ul><ul><li>selectively permeable </li></ul></ul><ul><ul><li>allows some substances to cross more easily than others </li></ul></ul><ul><ul><ul><li>hydrophobic vs hydrophilic </li></ul></ul></ul><ul><li>Made of phospholipids , proteins & other macromolecules </li></ul>
  24. 26. Phospholipid Bilayer <ul><li>Lipids </li></ul><ul><ul><li>Organic compounds </li></ul></ul><ul><ul><li>Fats + Oils </li></ul></ul><ul><ul><li>Non-polar </li></ul></ul><ul><ul><li>Insoluble in water (Not attracted to water) </li></ul></ul><ul><li>Phosphate Head </li></ul><ul><ul><li>Polar </li></ul></ul><ul><ul><li>Water-soluble (Attracted to water) </li></ul></ul>Here is what a phospholipid bi-layer looks like as a sphere FATTY ACIDS POLARHEAD Phosphate Group Glycerol Backbone Water-Soluble Water-Insoluble
  25. 27. <ul><li>The internal composition of the cell is maintained because the plasma membrane is selectively permeable to small molecules. </li></ul><ul><li>Only small, relatively hydrophobic molecules are able to diffuse across a phospholipid bilayer at significant rates by using passive diffusion. </li></ul>Permeability of phospholipid bilayers
  26. 28. Transport Across Membranes
  27. 29. Transport Across Membranes: PASSIVE DIFFUSION The movement of molecules or ions from a region where they are at a high concentration to a region of lower concentration
  28. 31. <ul><li>Gases (oxygen, carbon dioxide) </li></ul><ul><li>Water molecules (rate slow due to polarity) </li></ul><ul><li>Lipids (steroid hormones) </li></ul><ul><li>Lipid soluble molecules (hydrocarbons, alcohols, some vitamins) </li></ul><ul><li>Small noncharged molecules (NH 3 ) </li></ul>SIMPLE DIFFUSION
  29. 32. <ul><li>Ions </li></ul><ul><li>(Na + , K + , Cl - ) </li></ul><ul><li>Sugars (Glucose) </li></ul><ul><li>Amino Acids </li></ul><ul><li>Small water soluble </li></ul><ul><li> molecules </li></ul><ul><li>Water (faster rate) </li></ul>FACILITATED DIFFUSION
  30. 33. How do molecules move through the plasma membrane by facilitated diffusion? <ul><li>Channel and Carrier proteins are specific: </li></ul><ul><li>Channel Proteins allow ions, small solutes, and water to pass </li></ul><ul><li>Carrier Proteins move glucose and amino acids </li></ul><ul><li>Facilitated diffusion is rate limited, by the number of proteins channels/carriers present in the membrane. </li></ul>
  31. 34. <ul><ul><li>Osmosis is the diffusion of water across a differentially permeable membrane. </li></ul></ul><ul><ul><li>Osmotic pressure is the pressure that develops in a system due to osmosis. </li></ul></ul>OSMOSIS
  32. 35. Concentration of water <ul><li>Direction of osmosis is determined by comparing total solute concentrations </li></ul><ul><ul><li>Hypertonic - more solute, less water </li></ul></ul><ul><ul><li>Hypotonic - less solute, more water </li></ul></ul><ul><ul><li>Isotonic - equal solute, equal water </li></ul></ul>water net movement of water hypotonic hypertonic
  33. 36. Active Transport <ul><li>Cells may need to move molecules against concentration gradient </li></ul><ul><ul><li>shape change transports solute from one side of membrane to other </li></ul></ul><ul><ul><li>protein “pump” </li></ul></ul><ul><ul><li>“ costs” energy = ATP </li></ul></ul>“ The Doorman” conformational change ATP low high
  34. 40. <ul><ul><li>Endocytosis </li></ul></ul><ul><ul><li>Vesicles form as a way to transport molecules into a cell </li></ul></ul><ul><ul><li>a. Phagocytosis </li></ul></ul><ul><ul><li> Large,particulate matter ( Bacteria, viruses, and aged or dead cells). </li></ul></ul><ul><ul><li>b. Pinocytosis </li></ul></ul><ul><ul><li>Liquids and small particles dissolved in liquid </li></ul></ul>
  35. 41. <ul><ul><li>Exocytosis </li></ul></ul><ul><ul><li>Vesicles form as a way to transport molecules out of a cell </li></ul></ul>
  36. 42. Cytoplasm <ul><li>Thick, clear liquid residing between the cell membrane holding organelles </li></ul><ul><li>many of the complex chemical reactions/ metabolic pathways take place here such as: </li></ul><ul><li>Glycolysis </li></ul><ul><li>gluconeogenesis </li></ul><ul><li>biosynthesis of sugars, fatty acids, and amino acids </li></ul>
  37. 43. Mitochondria * site of cellular respiration * POWERHOUSE OF A CELL Where energy is released from nutrients * there are MANY in a single cell * has two layers, makes up a double membrane
  38. 44. <ul><li>Act similar to electric power plant </li></ul><ul><li>Up to 300 to 800 per cell </li></ul><ul><li>Come from cytoplasm in EGG </li></ul><ul><li>You inherited your mitochondria from your mother </li></ul>
  39. 45. certain organelles originated as free-living bacteria that were taken inside another cell as endosymbionts . Mitochondria developed from proteobacteria Can replicate itself: BINARY FISSION ENDOSYMBIOSIS
  40. 46. <ul><li>(1) outer membrane </li></ul><ul><li>It is fairly smooth. </li></ul><ul><li>It is composed of phospholipid bilayer protein. </li></ul><ul><li>it has channel protein: hole protein , permit that small molecule substance freely pass. </li></ul>The ultrastructure of mitochondrion
  41. 47. <ul><li>(2)inner membrane </li></ul><ul><li>they are more proteins than phospholipids. </li></ul><ul><li>it has no hole protein , so penetrability is weak . </li></ul>
  42. 48. <ul><li>(3) intermembrane space </li></ul><ul><li>it contains enzymes . It can catalyze ATP to create ADP. </li></ul><ul><li>(4)Matrix </li></ul><ul><li>Enzymes are abundant in the matrix . It also contains mitochondrial genetic system including DNA and ribosome. </li></ul><ul><li>(5) elementary particle </li></ul><ul><li>it also call ATP synthase. </li></ul><ul><li>it lies in the inner membrane . </li></ul>
  43. 49. The Functions of mitochondrion <ul><li>Production of ATP through respiration </li></ul><ul><li>cellular metabolism  </li></ul><ul><li>citric acid cycle or the Krebs Cycle </li></ul>
  44. 50. Chloroplasts chloroplasts in plant cell cross section of leaf leaves chloroplast absorb sunlight & CO 2 make energy & sugar chloroplasts contain chlorophyll CO 2
  45. 51. Structure <ul><li>Chloroplasts </li></ul><ul><ul><li>double membrane </li></ul></ul><ul><ul><li>stroma </li></ul></ul><ul><ul><ul><li>fluid-filled interior </li></ul></ul></ul><ul><ul><li>thylakoid sacs </li></ul></ul><ul><ul><li>grana stacks </li></ul></ul><ul><li>Thylakoid membrane contains </li></ul><ul><ul><li>chlorophyll molecules </li></ul></ul><ul><ul><li>electron transport chain </li></ul></ul>outer membrane inner membrane thylakoid granum stroma
  46. 53. Nucleus * surrounded by a nuclear membrane * only found in EUKARYOTES * contains genetic material (DNA) in the form of chromosomes that controls the activities of the cell * serves as the information and administrative center of the cell
  47. 55. <ul><li>Nucleoplasm </li></ul><ul><li>Nuclear envelope </li></ul><ul><li>Nuclear pores </li></ul><ul><li>Chromatin </li></ul><ul><ul><li>DNA + associated proteins </li></ul></ul><ul><li>Nucleolus </li></ul><ul><li>internal structure of nucleus, site of ribosome assembly </li></ul><ul><li>Chromatin vs. Chromosome </li></ul>Nucleus: Structure
  48. 56. The Major Functions of the Nucleus <ul><li>stores the cell's hereditary material, or DNA </li></ul><ul><li>coordinates the cell's activities </li></ul><ul><li>-intermediary metabolism </li></ul><ul><li>-growth </li></ul><ul><li>-protein synthesis </li></ul><ul><li>-reproduction (cell division) </li></ul>
  49. 57. Endoplasmic Reticulum (ER) - a series of interconnecting channels associated with storage, synthesis, and transport of substances within the cell two types: A) rough --the 'ER' studded with ribosomes B) smooth --the 'ER' without any ribosomes
  50. 58. Rough endoplasmic reticulum production and processing of specific proteins at ribosomal sites.  
  51. 60. <ul><li>carbohydrate metabolism </li></ul><ul><li>regulation of calcium ions </li></ul><ul><li>synthesis of steroids and lipids </li></ul><ul><li>drug detoxification </li></ul><ul><li>metabolism of steroids </li></ul>Smooth endoplasmic reticulum
  52. 61. Ribosomes Protein Synthesis &quot;translates&quot; the genetic information from ` RNA into proteins
  53. 62. <ul><li>looks like a stack of flattened pancakes </li></ul><ul><li>All of the proteins and lipids synthesized by the RER and SER are sent to the golgi.  </li></ul><ul><li>sorts, modifies, and packages the products of the RER and SER before sending them to their final destination inside or outside of the cell. </li></ul>Golgi Apparatus
  54. 65. Vacuole &quot; a &quot;space&quot; in a cell that contains water or other materials; usually for storage A) food vacuoles--store food B) contractile vacuoles-- squeeze out excess water
  55. 66. <ul><li>Centrioles </li></ul><ul><ul><li>found in animal cells; rare in plants </li></ul></ul><ul><ul><li>cylindrical structures (like cans) found in the cytoplasm that appears to function during cell division (reproduction) </li></ul></ul><ul><ul><li>involved in the organization of the mitotic spindle and in the completion of cytokinesis </li></ul></ul> 
  56. 67. <ul><li>Cell Wall </li></ul><ul><ul><li>found mostly in plant cells (some monerans, protists, and fungi too) </li></ul></ul><ul><ul><li>a non-living structure which surrounds and supports a cell </li></ul></ul><ul><ul><li>made of cellulose, a complex carbohydrate </li></ul></ul>
  57. 68. Lysosome “ Suicidal bags of the cell” a vacuole that contains digestive enzymes; helps in the process of nutrition by breaking down nutrients in the cell
  58. 69. <ul><li>Peroxisomes </li></ul><ul><li>helps to rid the body of the host organism of toxins </li></ul><ul><li>breakdown of very long chain fatty acids through beta-oxidation </li></ul>
  59. 70. <ul><li>Cilia and Flagella </li></ul><ul><ul><li>these are hair-like organelles that extend from the surface of many different types of cells </li></ul></ul><ul><li>cilia--are typically smaller than flagella, but they cover the outside of the organism </li></ul><ul><li>flagella--are much longer than cilia, but there usually are few on a single cell </li></ul><ul><ul><li>these structures usually aid in movement </li></ul></ul><ul><ul><li>they can also help sweep materials along the outside of a cell </li></ul></ul>