CLASS: Fundamentals 1Scribe: Mathew Owens

8-9-2011

11:00 – 12:00

CotlinProof: Gary Cramer

Cellular Structure and Organelles Page1 of 4

  1. Lysosomes [S47]
  2. Lysosome
  3. Membrane bound organelle that contains enzymes that degrade other molecules

A.Contains proteases, lipases, nucleases

  1. Lysosomal enzymes are phosphorylated with mannose (a sugar), which targets them for transport to the lysosome.
  1. Plasma membrane vesicles called endosomes or phagosomes also deliver ingested material to lysosome for destruction.

A.Ex. LDL is taken up by endosome and then taken to the lysosome for degradation.

  1. PH is about 5-5.5 (acidic environment)
  1. Lysosomes [S 48]
  2. Lysosomes have many hydrogen pumps that are continually pumping hydrogens into the lysosome.
  3. All of digestive enzymes are active at low PH.

A.This is important because you do not want these proteins active everywhere else in the cell.

  1. Lysosomes [S 49]
  2. On EM’s lysosomes show up as electron dense vesicles. (She said do not worry about this.)
  3. Endocytosis and Endosomes [S 50]
  4. Picture of receptor mediated endocytosis.
  5. Receptors that specifically grab molecules and take things in.
  6. Endosomes will come in and bind to the receptors and then bring their material to the lysosome.
  7. Phagocytosis and Phagosomes [S 51]
  8. Vesicles that are much larger same idea they bring in large material and they bring in material to the lysosome.
  9. Peroxisomes [S 52]
  10. Membrane-bound organelle also involved in oxidative reactions
  11. Peroxisomes break down fatty acids and lipids.

A. They do not provide energy through oxidation.( Energy is provided through oxidation in the mitochondria , Do not get these two confused)

  1. Paroxysmal proteins are synthesized in the cytoplasm and transported into the organelle using a specific amino acid sequence.
  2. Genetic defects in peroxisomal biogenesis cause several forms of mental retardation.
  1. Peroxisomes [S 53]
  2. Picture of peroxisomes, they are the small black dots.
  3. Mitochondria [S54]
  4. Double membrane bound (Inner and outer membrane), powerhouse of the cell (bulk of ATP is synthesized here)
  5. Found all over the cell, clusters are found in locations with high energy demand
  6. Ex sperm tails, contractile apparatus of muscles, active transport of membranes, and nerve terminals
  7. Also involved with apoptosis (cell death)
  8. Have their own DNA and protein synthesizing apparatus and make their own proteins.
  9. Mitochondria form differently from other organelles, by pinching in two, they do not divide synchronously with cell division.
  10. Mitochondria [S 55]
  11. Picture of a mitochondria
  12. The dense knobs are proteins of the electron transport chain.
  13. Organization of Mitochondria [S 56 ]
  14. Picture that help depicts between the inner and outer membrane.
  15. Overview of Mitochondrial Functions [S 57]
  16. Glycolysis occurs in the cytosol and results in the formation of pyruvate.
  17. Pyruvate and Fatty acids are transported into the mitochondria

A. Citric Acid cycle, Krebs cycle, TCA cycle occur in the matrix

  1. She said this was a brief overview, of the functions, and that we will get a more detailed presentation later.
  1. Mitochondria [S 58]
  2. another picture of the mitochondria. (can be different sizes)

Cellular structures and Organelles 2

  1. Inclusions [S 3]
  2. Deposits in cells found in the cytosol
  3. Glycogen, lipids, pigments (hemosiderin, melanin), crystals
  4. Proteasome [S 4].
  5. Another structure involved with degradation
  6. Not part of membrane system
  7. Found in cytosol and nucleus
  8. If the cell does not need protein anymore the protein will be targeted and sent to proteasome
  9. Ubiquitin is an amino acid peptide that is used as the signal to direct the protein to the proteasome.
  10. Lysosome vs. Proteasome
  11. Lysosome are membrane bound organelle and will receive lots of materials and will have lipases, nucleases, and proteases
  12. Proteasome is particular for proteins found in the cytosol
  13. The Cytoskeleton [S 5]
  14. Is the structural framework of given cell.
  15. Composed of three protein polymers:
  16. microtubules, active filaments, and intermediate filaments
  17. Will help dictate the shape and organization of the cell and also how the cell will interact with its environment.
  18. Organization of the Cytoskeleton [S 6]
  19. Diagram depicting a chain of epithelium.
  20. Green =micro tubules
  21. Usually run towards the nucleus and outward.
  22. Red = actin
  23. Very localized under plasma membrane to help give support.

iii light blue = Intermediate filaments

1. Generally criss cross the cell which helps withstand the pushing and pulling of cells.

  1. Microfilaments, Intermediate filaments, and Microtubules [S 7]
  2. Microtubules
  3. Rigid column shape structures
  4. Intermediate filaments
  5. Rope like filaments
  6. Microfilaments (ex. actin)
  7. Filament disarray
  8. Each one of these structures are all polymers of smaller molecules
  9. Microtubules [S 8]
  10. Are the largest of the three (microtubules, intermediate filaments, and microfilaments)
  11. Are made up of a tubulin dimer (alpha and beta)
  12. Very organized and specific in how they are assembled
  1. Microtubules [S 9]
  2. Help direct flow in a sense of acting as tracks in the cell.
  3. Kinesin-moves vesicles and RNA out along the Microtubules.
  4. Dynein- moves cargo from the cell membrane toward the nucleus.
  5. Help form mitotic apparatus and move chromosomes to the poles of the cell. (during mitosis)
  6. Microtubules [S 10]
  7. Microtubules form spindle fibers and are involved in chromosomal movement during mitosis
  8. Microtubules are found in the length of axons of neurons and help the axon stay intact.
  9. Microtubules are major components of cilia and flagella.
  10. Involved with centrioles
  11. Anchoring site in the cell
  12. Arrangement of Microtubules [S 11]
  13. Picture of Mitosis [S 12]
  14. Blue is chromosomes, yellow is microtubules
  15. Structure of Actin filament [S 13]
  16. Made up of actin monomers
  17. Have a plus and minus end, and specific in how they stack, very dynamic (can be longer or shorter depending on how long or short they need to be)
  18. Intracellular Actin (Microfilament) [S 14]
  19. Actin filaments also help reinforce the surface of the cell by being anchored in the plasma membrane
  20. Actin filaments support finger-like projections of the plasma membrane for transporting to increase surface area for transporting nutrients.
  21. Genetic defects in a membrane associated actin binding protein, dystrophin cause most of the common forms of muscular dystrophy.
  22. Provide tracks for the ATP powered motor proteins that produce most cellular movement including transport of organelles and movement of chromosomes during mitosis.
  23. Actin [S 15]
  24. picture of Actin network
  25. Model for cell movement [S 16]
  26. Actin is involved with movement of a cell, very dynamic
  27. actin’s ability to assemble and disassemble allows the cell to move
  28. Intermediate Filaments [S 17]
  29. Static structures, not as dynamic as actin or microfilaments
  30. Will have rope like properties, more flexible (help cell be able to stretch)
  31. Intermediate filaments [S 18]
  32. Flexible, strong intracellular tendons that are used to reinforce cell structure.
  33. All intermediate filaments are related to the keratin molecule.
  34. Filaments characteristically form bundles that link the plasma membrane to the nucleus.
  35. Some reinforce the nuclear envelope.
  36. Genetic defects involved with Intermediate filaments.
  37. Blistering of skin
  38. Keratin Filaments in Epithelial Cells [S 19]
  39. Picture of epithelial cells stained for keratin.
  40. Mechanical strength of filaments [S 20]
  41. Graph depicting how intermediate filaments are more likely to withstand forces and not snap under various levels of tension compared to microtubules and actin filaments.
  42. The Cell Cycle [S 21]
  43. Diagram of cell cycle
  44. The Cell Cycle [S 22]
  45. Eukaryotic cell cycles are divided in two major stages; interphase and mitosis.
  46. Interphase- time when cell does not divide
  47. G1 is a metabolically active phase
  48. Can either enter the Go phase or S phase
  49. Go phase is when a cell will not divide for a long period of time.
  50. When receives signal that it is time to divide it will move into the S phase
  51. S stands for synthesis; this is the stage where the cell replicates its DNA.
  52. After the S phase it moves into G2 phase.
  53. The G2 phase is a second growth phase;this is when the cell physically bulks up to have enough material for Mitosis. Also a period of proofreading.
  54. Mitosis – time where cell divides (cytokinesis= cytoplasmic division)
  55. Cell Cycle …continued [S 23]
  56. Checkpoints and feedback controls coordinate the different phases of the cell cycle to prevent mutations.
  57. After DNA replication has occurred, initiation of a new S phase is prevented until the cell has passed through mitosis.
  58. Events that occur when a cell divides [S 24]
  59. Prophase
  60. Where cell assembles, and microtubules attach to chromosomes.
  61. Metaphase
  62. The chromosomes line up in the middle of the cell.
  63. Anaphase
  64. The chromosomes are pulled apart towards opposite poles of the cell.
  65. Telophase
  66. When the cell undergoes a splitting into two daughter cells.
  67. Development and Differentation [S 25]
  68. Majority of our cells do not divide on a daily basis and are rested in the Go phase.
  69. Some cells can never go through mitosis
  70. Neurons
  71. Adult Cardiac muscles
  72. Some differentiated cells have short life spans and are continually replaced (going through mitosis)
  73. Ex. Skin cells
  74. Programmed Cell Death (Apoptosis) [S 26]
  75. Programmed cell death plays a key role in:
  76. Maintenance of adult tissue
  77. Embryonic development
  78. Programmed cell death is a process of apoptosis, which is different from accidental death of cell resulting from acute injury, which is called necrosis.
  79. Apoptosis is essential for the health of the organism.
  80. Events in Apoptosis [S 27]
  81. Enzymes associated with this process are called caspases.
  82. Caspases digest DNA, cytoplasmic proteins, and organelles.
  83. The membrane remains intact until final stages of cell death.
  84. Macrophages readily devour the debris of the dying cell and much of the digested material is used in the building of new cells.
  85. Introduction to Histology and Microscopic Techniques
  86. Histology
  87. Study of microscopic structures of tissues.
  88. Four major tissue types
  89. Epithelial-
  90. layers of cells that line our skin:
  91. Ex. Gi tract, Reproductive Tract
  92. Connective-
  93. cells involved with making matrix
  94. Muscle-
  95. Cardiac, smooth, skeletal
  96. Nerve