Human A&P I

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Human A&P I
2012-09-26 19:41:13
Module Two Part CCCC

Overview of Metabolic Reactions
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  1. Metabolism
    Sum total of the chemical reactions occurring in the body cells.
  2. Anabolism
    Energy-requiring building phase of metabolism in which simpler substances are combined to form more complex substances.
  3. Catabolism
    Process in which living cells break down substances into simpler substances.
  4. Cellular Respiration
    Metabolic processes in which ATP is produced. Particularly related to the breakdown of glucose.
  5. Phosphorylated
    Process in which ATP is indirectly hydrolyzed - enzymes shift high energy phosphate groups to other molecules. Primes a molecule to change in a way that increases its activity, produces motion, or does work.
  6. Stage 1 of Energy Processing
    Digestion in the gastrointestinal tract. Absorbed nutrients are transported in blood to tissue cells.
  7. Stage 2 of Energy Processing
    Occurs in the tissue cells. Newly delivered nutrients are either built into lipids, proteins, and glycogen by anabolic pathways or broken down by catabolic pathways to pyruvic acid and acetyl CoA in the cell cytoplasm.
  8. Stage 3 of Energy Processing
    Occurs in the mitochondria. Almost entirely catabolic. Requires oxygen, and completes breakdown of foods, producing carbon dioxide and water and harvesting large amounts of ATP.
  9. Oxidation
    Process of substances combining with oxygen or the removal of hydrogen. The gain of oxygen or the loss of hydrogen.
  10. Oxidation-reduction (redox) reaction
    A reaction that couples the oxidation (loss of electrons) of one substance with the reduction (gain of electrons) of another substance.
  11. Dehydrogenases
    Enzymes that catalyze redox reactions in which hydrogen atoms are removed.
  12. Oxidases
    Enzymes that catalyze the transfer of oxygen in oxidation-reduction reactions.
  13. NAD+
    Nicotinamide adenide dinucleotide. An important coenzyme based on niacin, important to the oxidative pathways.
  14. FAD
    Flavin adenide dinucleotide. An important enzyme derived from riboflavin that is important to the oxidative pathways.
  15. Substrate Level Phosphorylation
    A mechanism that occurs when high-energy phosphate groups are transferred directly from phosphorylated substrates (metabolic intermediates such as glyceraldehyde 3-phosphate) to ADP.
  16. Oxidative phosphorylation
    Process of ATP synthesis during which an inorganic phosphate group is attached to ADP; occurs via the electron transport chain within the mitochondria. Is an example of a chemiosmotic process.
  17. Chemiosmotic processes
    Couple the movement of substances across across membranes to chemical reactions.
  18. How does glucose enter tissue cells?
    By facilitated diffusion
  19. How does glucose enter tissue cells?
    Facilitated diffusion, process is enhanced by insulin.
  20. glucose-6-phosphate
    Immediately after entering a cell, glucose is phosphorylated to glucose-6-phosphate by transfer of a phosphate group to its sixth carbon during a coupled reaction with ATP.

    Glucose + ATP -> glucose-6-PO4 + ADP
  21. Glycolysis
    Breakdown of glucose to pyruvic acid-an anaerobic process. Also called the glycolytic pathway, occurs in the cytosol of cells.
  22. Anaerobic process
    Means that glycolysis does not use oxygen and occurs whether or not oxygen is present.
  23. Phase 1 - Glycolysis (Sugar Activation)
    • Phyosphorylation activates glucose. Glucose is converted to fructose-1, 6-bisphosphate.
    • The two separate reactions of the sugar with ATP provide the activation energy needed to prime the later stages of the pathway, so phase 1 is sometimes called the energy investment phase.
  24. Phase 2 - Glycolysis (Sugar Cleavage)
    Fructose-1, 6-bisphosphate is cleaved into two 3-carbon fragments. These fragments exist as one of two isomers - glyceraldehyde 3-phosphate or dihydroxyacetone phosphate.
  25. Phase 3 -Glycolysis (Sugar Oxidation and ATP Formation)
    The 3-carbon fragments are oxidized (by removing hydrogen) and 4 ATP molecules are formed. Phase 3 consists of 6 steps.
  26. Lactic Acid
    Product of anaerobic metabolism, especially in muscle.
  27. Aerobic
  28. Krebs Cycle
    Aerobic metabolic pathway occurring within mitochondria, in which food metabolites are oxidized and CO2 is liberated, and coenzymes are reduced. Also called the citric acid cycle.
  29. How does pyruvic acid enter mitochondria?
    Since it is a charged molecule, pyruvic acid enters mitochondria by active transport with the help of a transport protein.
  30. What is the "transitional phase"?
    The process of converting pyruvic acid to acetyl CoA. This only occurs once the pyruvic acid has already entered the mitochondria.
  31. What are the three steps to the transitional phase?
    • 1. Decarboxylation. In this step, one of pyruvic acid's carbons is removed and released as a carbon dioxide gas, a process called decarboxylation. CO2 diffuses out of the cells into the blood to be expelled by the lungs. This is the first time that CO2 is released during cellular respiration.
    • 2. Oxidation. The remaining 2C fragments (acetic acid) is oxidized by removing hydrogen atoms, which are picked up by NAD+.
    • 3. Formation of acetyl CoA. Acetic acid is combined with coenzyme A to produce the reactive final product, acetyl coenzyme A (acetyl CoA). Coenzyme A is sulfure containing coenzyme derived from vitamin B3.
  32. Why do biochemists prefer to call the Krebs cycle the citric acid cycle?
    After the transitional phase, Acetyle CoA is ready to enter the Krebs cycle and be broken down completely by mitochondrial enzymes. Coenzyme A shuttles the 2-carbon acetic acid to an enzyme that condenses it with a 4-carbon acid called oxaloacetic acid to produce the 6-carbon citric acid.
  33. What are the products of the Krebs cycle?
    Because two decarboxylations and four oxidations occur, the products are two CO2 molecules and four molecules of reduced coenzymes (3 NADH + H+ and 1 FADH2)

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