Connection to Metabolic Pathways

  1.                                                               i.      Free __is not common in diets; calories are from__
                                                                ii.      Glycolysis can accept several carbs (especially disaccharides) for __
    1.      Starch à __ -->__à __
    2.      Glycogenà __
    • glucose
    •  fats, proteins, sucrose and other disaccharides, and starch
    • catabolism
    • glucose
    • pyruvate by glycolysis
    • CAC
    • glucose between meals as fuel 
  2. Proteins can be used, but what must happen first?
    a.      Many amino acids used to__
                                                                                                                                          i.      If in excess, they are __
    1.      Firstwhatmusthappen?
    • digested to amino acids first
    •  build new proteins
    • converted by enzymes to intermediates of glycolysis and the CAC
    • , their amino groups must be removed (deamination) and excreted
  3.                                                               i.      Fats
    1.      After digestion into __, the __is converted to glyceraldehydes-3-phosphate__, an intermediate of glycolysis
    • glycerol and fatty acids
    • glycerol
    • glycerol
  4. a.      Most energy in fatty acids
                                                                                                                                          i.      __breaks the fatty acids down to__, which enter CAC as __
    1.      __also generates NADH and FADH2
    • Beta oxidation
    •  two-carbon fragments
    • acetyl CoA
    • Beta oxidation
  5. True or Flase: Carbs make twice as much ATP as fats.
    false; other way around
  6. a.      Biosynthesis
                                                                  i.      Cells need substance as well as energy; not all organic molecules destined for__
                                                                ii.      Food also provides__ for production of molecules
    1.      Amino acidsà directly into proteins
                                                              iii.      Molecules not present readily
    1.      Compounds formed as intermediates of glycolysis and the CAC can be __
                                                              iv.      __and the __function as metabolic interchanges that enable our cells to convert some kinds of molecules to others as we need them 
    •  oxidation to make ATP
    •  carbon skeletons
    • changed into precursors for synthesis of molecules
    • Glycolysis and the CAC
  7. a.      Feedback Mechanisms
                                                                  i.      The cell doesn’t waste energy making unneeded molecules
    1.      If excess, the anabolic pathway that synthesizes that molecule is __ (ex: amino acid)
    a.      __: end product inhibits the enzyme that catalyzes an early step of the pathway, preventing the needless diversion of key metabolic intermediates from uses that are more urgent
    • s turned off
    • Feedback inhibition
  8.                                                               i.      Cell also controls __
    1.      If ATP concentration drops, respiration __

    2.      Plenty of ATP results in __
    3.      Control is regulated at strategic points in the pathway
    • catabolism
    • speeds up
    • slowing down of respiration
  9. Explain phosphofructokinase.
    • a.      Phosphofructokinase catalyzes step three of glycolysis
    •                                                                                                                                       i.      First step that commits substrate irreversibly to the glycolytic pathway
    • 1.      Through control, the cell can speed up or slow down the entire catabolic process
    •                                                                                                                                     ii.      It is a pacemaker 
  10.                                                               i.      Phosphofructokinase
    1.      Allosteric enzyme with receptor sites for specific __ and __
    a.      Inhibited by __, which slows down glycolysis
    b.      Stimulated by __
    • inhibitors and activators
    • ATP
    • AMP
  11. Explain citrate.
    • If accumulates in mitochondria, some of it inhibits phosphofructokinase, helping synchronize the rates of glycolysis and the CAC
    • - citrate accumulates: glycolysis slows down and supply of acetyl groups to CAC decreases
    • - citrate consumption increases, glycolysis accelerates and meets demand
Card Set
Connection to Metabolic Pathways