Cell Metabolism Part 1


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  • Troponin I and T are structural components of cardiac muscle. They are released into the bloodstream with myocardial injury. They are highly specific for myocardial injury--more so than CK-MB--and help to exclude elevations of CK with skeletal muscle trauma. Troponins will begin to increase following MI within 3 to 12 hours, about the same time frame as CK-MB. However, the rate of rise for early infarction may not be as dramatic as for CK-MB. Troponins will remain elevated longer than CK--up to 5 to 9 days for troponin I and up to 2 weeks for troponin T. This makes troponins a superior marker for diagnosing myocardial infarction in the recent past--better than lactate dehydrogenase (LDH). However, this continued elevation has the disadvantage of making it more difficult to diagnose reinfarction or
  • (LDH) Lactate dehydrogenase  - Total LDH will begin to rise 2 to 5 days after an MI; the elevation can last 10 days. 140-280 U/L Normal Adult Range: 0 - 250 U/L Optimal Adult Reading: 125
  • This can be tested by looking at Siamese cats that have been left outdoors over winter (all black), or raised in very hot climates (all white). Of course you can also put boots on the cats and get cats with white stockings, or tape down their ears and get white ears.
  • Cell Metabolism Part 1

    1. 1. Ch 4: Cellular Metabolism, Part 1 <ul><li>Energy as it relates to Biology </li></ul><ul><ul><li>Energy for synthesis and movement </li></ul></ul><ul><ul><li>Energy transformation </li></ul></ul><ul><li>Enzymes and how they speed reactions </li></ul><ul><li>Metabolism and metabolic pathways </li></ul><ul><ul><li>Catabolism (ATP production) </li></ul></ul><ul><ul><li>Anabolism ( Synthesis of biologically important molecules ) </li></ul></ul>
    2. 2. Energy in Biol. Systems: <ul><li>General definition of energy: Capacity to do work </li></ul><ul><ul><li>Chemical, transport, movement </li></ul></ul><ul><li>First Law of Thermodynamics: Energy can neither be created nor destroyed </li></ul><ul><li>Ultimate source of energy: Sun! </li></ul>Fig 4-2 2 types of energy: <ul><li>Kinetic energy = motion </li></ul><ul><ul><li>examples ? </li></ul></ul><ul><li>Potential energy = stored energy </li></ul><ul><ul><li>examples ? </li></ul></ul>
    3. 3. Energy (E) Transfer Overview Figure 4-1
    4. 4. Potential Energy Kinetic Energy WORK heat (~ 70% of energy used in physical exercise)
    5. 5. Bioenergetics = study of energy flow through biol. systems <ul><li>Chemical reactions transfer energy </li></ul><ul><li>A + B C + D </li></ul>Substrates or reactants Products Speed of reaction = Reaction rate Initial force = Activation Energy
    6. 6. Potential Energy Stored in Chemical Bonds of Substrate can be . . . <ul><li>transferred to the chemical bonds of the product </li></ul><ul><li>released as heat (usually waste) </li></ul><ul><li>used to do work ( = free energy) </li></ul>
    7. 7. Chemical Reactions p 93 <ul><li>Activation energy </li></ul><ul><li>Endergonic vs. exergonic reactions </li></ul><ul><li>Coupled reactions </li></ul><ul><ul><li>Direct coupling vs. indirect coupling </li></ul></ul><ul><li>Reversible vs. irreversible reactions </li></ul>
    8. 8. Activation Energy Fig 4-3
    9. 9. Endo- and Exergonic Reactions Which is which?? ATP + H 2 O ADP + P i + H + + Energy
    10. 10. Enzyme (= Biol. Catalyst) <ul><li>Enzymes are proteins </li></ul><ul><li> rate of chemical reaction by lowering activation energy </li></ul><ul><li>is not changed itself </li></ul><ul><ul><li>It may change DURING the reaction </li></ul></ul><ul><li>does not change the nature of the reaction nor the result </li></ul><ul><li>is specific </li></ul>Some important characteristics of an enzyme: Fig 4-6
    11. 12. Enzymes lower activation energy: All chemical reactions in body must be conducted at body temp.!! How do enzymes lower activation energy ?
    12. 13. <ul><li>Enzymes bind to reactant molecules and bring them together in best position for rx. </li></ul>
    13. 14. Some more characteristics of enzymes: <ul><li>Usually end in –ase </li></ul><ul><li>Inactive form: -ogen </li></ul><ul><li>in few cases RNA has enzymatic activity (eg: rRNA  peptide bond) </li></ul><ul><li>Isoenzymes may be produced in different areas of the body </li></ul><ul><ul><li>E.g., LDH </li></ul></ul>
    14. 15. <ul><li>Small region of the complex 3D structure is active (or binding) site. </li></ul><ul><li>Enzymes bind to substrate </li></ul>Active Site: Old: Lock-and-key model / New: Induced-fit model
    15. 16. Enzyme-substrate interaction: The old and the new model Lock and Key: Induced fit:
    16. 17. Enzyme Specificity <ul><li>Often: reaction with only one substrate </li></ul><ul><li>Sometimes: reaction with group of similar substrates </li></ul>
    17. 18. Naming of Enzymes <ul><li>Kinase </li></ul><ul><li>Phosphatase </li></ul><ul><li>Peptidase </li></ul><ul><li>Dehydrogenase </li></ul>mostly suffix -ase first part gives info on function examples
    18. 19. Isoenzymes = different models of same enzyme (differ in 1 or few aa) <ul><li>Examples: </li></ul><ul><li>Amylase </li></ul><ul><li>LDH -> importance in diagnostics </li></ul>Catalyze same reaction but under different conditions and in different tissues/organs
    19. 20. Enzyme Activity depends on <ul><li>Proteolytic activation (for some) </li></ul><ul><li>Cofactors & coenzymes (for some) </li></ul><ul><li>Temperature </li></ul><ul><li>pH </li></ul><ul><li>Other molecules interacting with enzyme </li></ul><ul><ul><li>Competitive inhibitors </li></ul></ul><ul><ul><li>Allosteric modulators </li></ul></ul>
    20. 21. 1) Proteolytic Activation <ul><li>Also </li></ul><ul><li>Pepsinogen Pepsin </li></ul><ul><li>Trypsinogen Trypsin </li></ul>
    21. 22. 2) Cofactors & Coenzymes structure: Inorganic molecules (?) function: conformational change of active site structure: Organic molecules (vitamin derivatives, FADH 2 ....) function: act as receptors & carriers for atoms or functional groups that are removed from substrate
    22. 23. Cofactors bind to active site
    23. 24. 3) Breakage of intramolecular bonds lead to ?
    24. 25. <ul><li>Tyrosine Melanin </li></ul><ul><li>Tyrosinase is temperature sensitive  does not function at cat’s core body temperature (101.5° F) </li></ul>Siamese Cats tyrosinase
    25. 26. 3)
    26. 27. 4) Molecules interacting with enzyme <ul><li>Competitive inhibitors : bind to active site </li></ul>block active site E.g.: Penicillin binds covalently (= irreversibly to important bacterial enzyme active site) Fig 4-13
    27. 28. 4) Molecules interacting with enzyme, cont’d <ul><li>Allosteric modulators (fig 4-14) : bind to enzyme away from active site change shape of active site (for better or for worse) </li></ul>= end product inhibition Special case:
    28. 29. Allosteric Modulation
    29. 30. Reaction Rate Depends on Enzyme & Substrate Concentration
    30. 31. Reversible Reactions follow the Law of Mass Action
    31. 32. Three Major Types of Enzymatic Reactions: <ul><li>Oxydation - Reduction reactions </li></ul><ul><ul><li>(transfer of electrons or protons (H + )) </li></ul></ul><ul><li>Hydrolysis - Dehydration reactions </li></ul><ul><ul><li>(breakdown & synthesis of water) </li></ul></ul><ul><li>Addition-Subtraction-Exchange (of a functional group) reactions </li></ul>
    32. 34. ?
    33. 35. Metabolism Catabolism Anabolism next time