Mitochondria, Lysosomes, and Peroxisomes S1M1

  1. Define -ome
    • Mass
    • Genome = mass of genes
  2. Define -soma
    • Body
    • Lysosome = Body where lysis occurs
  3. Mitochondria definition
    • A spherical organelle that is responsible for conversion of food to ATP.
    • Additionally it breaks down fatty acids to acetyl-CoA (used to make ATP)
  4. What are the two ways that ATP can be synthesized
    • In the Mitochondria by oxidative phosphorylation (uses oxygen), most ATP is made this way.
    • In the cytoplasm by glycolysis which breaks down glucose to a pyruvate (doesn't require oxygen)
  5. How much ATP does one glucose molecule yield when made in mitochondria
    36 ATP
  6. Breakdown of fatty acids to acetyl CoA can happen where
    • Mitochondria
    • Peroxisomes (doesn't yeild ATP)
  7. What are the inner foldings of the mitochondria called
  8. What are the four different portions of the Mitochondria
    • Matrix
    • Inner Membrane
    • Outer Membrane
    • Intermembrane space
  9. What is unique about the porins in the mitochondria
    • They are ion pores which are the only place in the human body that they are found
    • Can be found on bacteria and chloroplasts though
  10. Why does the intermembrane space of the mitochondria resemble the cytoplasm
    Because of the porins in the outer membrane allowing free flow
  11. Where are the mitochondria proteins encoded and translated
    • Encoded in the nucleus
    • Translated by cytoplasmic ribosomes
    • Imported to the mitochondria post translationally
  12. What is the matrix of the Mitochondria
    Space containing hundreds of enzymes including those required for oxidation of pyruvate and fatty acids, and for the citric acid cycle
  13. What are the functions of the inner membrane of the Mitochondria
    Contains proteins that carry out the oxidation reactions of the electron transport chain, and ATP synthase
  14. What is the significance of the outer membrane on mitochondria
    It contains large protein pores to the cytosol allowing all molecules to enter (5000 daltons or less) the intermembrane
  15. What is contained in the intermembrane space in mitochondria
    Several enzymes that use the ATP passing out of the matrix to phosphorylate other nucleotides
  16. Where are the mitochondria normally located in a given cell
    Near the site of high ATP utilization
  17. How many genes are in the circular mitochondrial DNA
    37 total genes (2 rRNA and 22 tRNA)
  18. Where is the mitochondrial DNA located, and how many are found in each
    In the Matrix, 2-10 mtDNA
  19. What is required for proteins sequenced in the nucleus to get to the mitochondria
    They must contain a mitochondria targeting sequence to be imported
  20. How are more mitochondria made
    It divides and doubles its DNA and structure ending in two full mitochondria
  21. Who do we get mitochondria from, mother or father
    Mother, the sperms mitochondria is marked with ubiquitin targeted for destruction after penetrating the egg
  22. What are the main steps to making ATP through oxidative phosphorylation
    • 1. Oxidation of the pyruvate and fatty acids to CO2 (via acetyl CoA) coupled to the reduction of the coenzymes NAD+ and FAD to NADH and FADH2
    • 2. Electrons from these reduced coenzymes are transferred via three electron transport complexes to O2, and electrons collect in the intermebrane space
    • 3. Protons (H+) flow back into the matrix space driven by the proton motive force through the protein complex ATP synthase coupling Pi to ADP making ATP
  23. What is cytochrome c and where is it located
    An electron transfer agent important to ATP production (cellular respiration) between the enzyme complexes in the mitochondrial membrane
  24. Proton Motive Force is
    When the matrix becomes negatively charged during ATP production causing an electrical gradient between the matrix and the intermembrane space. It provides fuel to ATP synthase's last mechanical step.
  25. Cristae are covered by what important structure
    ATP Synthase, as well as ATP transporters to distribute new ATP to the cytosol
  26. What is Cardiolipin
    A double phospholipid that contains four fatty acids, these pack tighter in the mitochondrial membrane, withstanding the stresses of the proton motive force.
  27. Where is cardiolipin made
  28. Define Lysosome
    A membrane bound organelle in the eukaryotic cells containing digestive enzymes.
  29. What are the two major pathways to degrade cellular components
    • 1. Proteasome - degrades damaged proteins tagged by ubiquitin. Degrades to amino acids that are recycled
    • 2. Lysosome - degrades proteins, lipids, Carbohydrates, DNA, RNA, ect.
  30. How is the signal for ubiquination exhibited
    It is normally buried in a healthy folded protein, but is exposed when the protein is worn
  31. What is the average half life of a cellular protein?
    24 hours
  32. Why are many proteins folded
    To protect the hydrophobic agents from contacting water and to cover ubiquinone
  33. Where are proteosomes found
    Throughout the cytoplasm and nucleoplasm
  34. How does ubiquitis know when to degrade a protein
    They are unfolded from their normal healthy state
  35. How do lysosomes degrade
    They have a low Ph (approx 5) creating a conducive environment for enzymes. This environment is created by H+ pumps in membrane
  36. Is a proteosome an organelle, why or why not
    It is not an organelle because it is not membrane bound.
  37. What are the three special properties of a lysosome membrane
    • 1. An ATP driven proton pump (maintain low Ph)
    • 2. A glycoprotein coat (protect from Ph)
    • 3. Transporter Channels (move trash out)
  38. How do lysosomes keep enzymes from escaping
    A glycoprotein inner coat
  39. The broken down products of the lysosome are moved out via
    • Facilitated diffusion
    • Active transport
    • By a co-transport using a proton (H+) gradient
  40. What are the three pathways causing degregation by a lysosome
    • Phagocytosis (eats whole bacteria)
    • Autophagy (old organelle wrapped in ER)
    • Endocytosis (matter consumed)
  41. Autophagy
    • The process of destruction of a cell in a phagosome made up of an ER membrane
    • Used in starvation to eat good organelles to survive
  42. Tay Sachs is a result of the absence of what
    Hexosaminidase A, which breaks down glycolipids in lysosomes, neurons are enriched highly with glycolipids but get overwhelmed with them if to abundant causing neurons to fail.
  43. Tay-Sachs is
    • Disease of Lysosomal storage, infants appear fine until motor and mental deterioration causing dementia. Beginning around 6 months old. Death 2-3yrs
    • Prevelant in Jews
  44. Define peroxisome
    • Small membrane bound (single membrane) organelle that uses molecular oxygen to oxidize organic molecules
    • Hydrogen peroxide is produced and degraded here
  45. Peroxisomes are bounded by and don't contain any
    A single membrane, contain no DNA, all proteins are imported
  46. Peroxisomes have the ability to do what rapidly
    They can proliferate rapidly when their functions are needed
  47. Why are peroxisomes so prevelant in hepatocytes
    • They detoxify many toxic substances taken in by the GI
    • All cells contain them though
  48. If a liver has more peroxisomes then normal, what could be a dietary habit of the patient
    They are a heavy drinker
  49. Catalase
    A peroxisomal matrix enzyme which utilizes H2O2 to oxidize many substances by peroxidative reaction
  50. What are the two major users of oxygen in a cell
    Mitochondria and Peroxisomes
  51. What process uses peroxisomes to break down fatty acid molecules to Acetyl CoA and then sends it to the Mitochondria for ATP Development
    Beta Oxidation (in mammals, it occurs in the mitochondria as well)
  52. The breakdown of fatty acids in peroxisomes produces
    Hydrogen Peroxide
  53. Peroxisomal diseases lead to what kind of disorders and why
    Nuerological disease, because peroxisome participates are used to make plasmalogens important to myelin production
  54. How are bile acids and peroxisomes connected
    Hydrogen peroxide (H2O2) a product of peroxisomes is crucial to bile acid production
  55. What are the ways the cell makes peroxisomes rapidly, and at normal speeds
    • De Nova formation, budding off of ER and addition of PTS (peroxisomal targeting signal)
    • Can also be made through fission
  56. Many diseases linked to Peroxisomal disorders, name one
    Zellweger's disease has a defect of not importing fatty acids usually degraded by peroxisomes. The accumulation of such causes organ failure and death
  57. Hydrogen peroxide H2O2 from Peroxisomes is used by what to break down many other substances such as alcohol, phenols, and formic acid
  58. Lysosomes can degrade what substances
    Potein, lipids, Carbs, DNA, RNA, ect.
Card Set
Mitochondria, Lysosomes, and Peroxisomes S1M1
Cell Biology