Ch 15.3

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DesLee26
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289343
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Ch 15.3
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2014-11-16 11:10:23
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Sam
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Biochem
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Test four
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  1. ·         ATP serves as the __ in biological systems rather than as a __
    o   The __ of the small amount of ATP is very high
    ·         The generation of ATP is one of the primary roles of __. The carbon in fuel molecules is __ to __; and, the resulting electrons are __and used to __
    • principal immediate donor of free energy
    • long-term storage form of free energy
    • turnover 
    • catabolism
    • oxidized to CO2
    • captured 
    • regenerate ATP from ADP and Pi
  2. ·         In aerobic organisms, the ultimate electron acceptor in the oxidation of carbon is __and the oxidation product is __. The more reduced a carbon is, the more __ is released by its __
    ·         When a fuel is oxidized, the oxidation takes place how
    o   The carbon-oxidation energy is used in some cases to create a compound with __ and in other classes to create an __. In either case, the end point is the __
    • O2 
    • CO2
    • free energy
    • oxidation
    • one carbon at a time
    • high phosphoryl-transfer potential
    • ion gradient
    • formation of ATP
  3. ·         Considering glyceraldehyde 3- phosphate, it is a __ formed from __; at the aldehyde level, it is not the __; oxidation of the aldehyde to an acid will __.
    o   The oxidation does not take place __. Instead, the carbon oxidation generates an __; and, the electrons released are captured by __, which has __. Thus, the __ can be coupled to the __
    • metabolite of glucose
    • oxidation of the sugar
    • most oxidized
    • release energy

    • directly
    • acyl phosphate, 1,3-BPG
    • NAD+
    • high phosphoryl-transfer potential
    • cleavage of 1,3-BPG 
    • synthesis of ATP
  4. ·         The energy of oxidation is initially trapped as a __ and then used to __. The oxidation energy of a carbon atom is transformed into __, first as __ and ultimately as __
    ·         __ is an effective means of storing free energy. The __ of __ across membranes, produced by oxidation of fuel molecules or by photosynthesis, powers the synthesis of most of the __ in cells. 
    • high-phosphoryl-transfer-potential compound
    • form ATP
    • phosphoryl-transfer potential
    • 1,3-BPG
    • ATP
    • Electrochemical potential
    • electrochemical potential of ion gradients
    • ATP
  5. ·         In general, ion gradients are __means of doing what?
    o   In animals, __ generated by the oxidation of carbon fuels accounts for more than __, called __
    • versatile 
    • coupling thermodynamically unfavorable reactions to favorable ones

    proton gradients

    • 90% of ATP generation
    • oxidative phosphorylation
  6. Energy from food is extracted in three stages
    Stage 1
    o   Stage 1: large molecules in food are broken down into smaller units, called digestion
  7. Energy from food is extracted in three stages
    Stage 2
    o   Stage 2: these numerous small molecules are degraded to a few simple units that play a central role in metabolism 
  8. Energy from food is extracted in three stages
    Stage 3
    ATP is produced from the complete oxidation of the acetyl unit of acetyl CoA
  9. §  It consists of the __ and __, which are the final common pathways in the oxidation of fuel molecules
    §  Acetyl coA brings __ into the __, where they are completely oxidized to __
    ·         __ of electrons are transferred (__ to __ and __ to __) for each acetyl group that is oxidized.
    ·         Then, a __ is generated as electrons flow from the __ to O2, and this gradient is used to synthesize ATP
    • citric acid cycle and oxidative phosphorylation
    • acetyl units
    • citric acid cycle
    • CO2
    • Four pairs
    • three to NAD+ and one to FAD
    • proton gradient
    • reduced forms of these carriers
  10. ·         ____: in aerobic organisms, the ultimate electron acceptor in the oxidation of fuel molecules is __. However, electrons are not __. Instead, fuel molecules transfer electrons to __, which are either __. The reduced forms of these carriers then transfer their __ to __
    Activated carriers of electrons for fuel oxidation

    O2

    transferred directly to O2

    special carriers

    • pyridine nucleotides or flavins
    • high-potential electrons to O2
  11. o   ______________ is a major electron carrier in the oxidation of fuel molecules. The reactive part of it is its __, a __derivative synthesized from the __. In the oxidation of a substrate, the __ accepts a hydrogen ion and two electrons, which are equivalent to a __. The reduced form of this carrier is called __. In the oxidized form, the nitrogen atom carries a __
    • NAD+ 
    • nicotinamide ring
    • pyridine 
    • vitamin niacin
    • nicotinamide ring of NAD+
    • hydride ion
    • NADH
    • positive charge.
  12. o   In this __, one hydrogen atom of the substrate is transferred to __, whereas the other appears in the solvent as a __. Both electrons lost by the substrate are transferred to the __

    o   ___is also an electron carrier that has an __. It can accept __, takin up __
    • dehydrogenation
    • NAD+
    • proton
    • nicotinamide ring
    • FAD 
    • isoalloxazine ring
    • two electrons
    • two protons
  13.         ___: __ are required in most biosynthesis because the precursors are __ than the products. So, __ is needed in addition to ATP
    o   The electron donor in most reductive biosynthesis is __, the reduced form of __.
    • An activated carrier of electrons for reductive biosynthesis
    • high-potential electrons
    • more oxidized
    • reducing power
    • NADPH
    • nicotinamide adenine dinucleotide phosphate
  14. §  NADPH differs from NADH in that the __. NADPH carries electrons in the same way as NADH.
    §  However, NADPH is used almost exclusively for __, whereas NADH is used primarily for the __. The extra phosphoryl group on NADPH is a __that enables enzymes to distinguish between __. 
    2’-hyroxyl group of its adenosine moiety is esterified with phosphate

    • reductive biosynthesis
    • generation of ATP
    • tag 
    • high-potential electrons to be used in anabolism and those to be used in catabolism.
  15. ·         __: __, another central molecule in metabolism, is a carrier of __ derived from __
    o   acyl groups are important in __ as __ and __as in __
    §  The __ in CoA is the reactive site. Acyl groups are linked to __ by __. 
    An Activated Carrier of Two-Carbon Fragments

    Coenzyme A

    acyl groups

    vitamin pantothenate

    • catabolism
    • oxidation of fatty acids
    • anabolism 
    • synthesis of membrane lipids
    • terminal sulfhydryl group'
    • CoA by thioester bonds
  16. ·         the resulting derivative is an __; an acyl group often linked to CoA is the __unit; this derivative is called __
    ·         The hydrolysis of a __is thermodynamically more favorable than that of an __ because the electrons of the __ cannot form __ with the C-S bond that are as stable as those that they can form with the C-O bond. 
    • acyl CoA
    • acetyl 
    • acetyl coA
    • thioester 
    • oxygen ester
    • C=O bond
    • resonance structures
  17. o   Consequently, acetyl CoA has a high __ because transfer of the acetyl group is __
    §  Acetyl CoA carries an __, just as ATP carries an activated phosphoryl group
    • acetyl-group-transfer potential
    • exergonic

    activated acetyl group
  18. o   __, __, and __ react slowly with __in the absence of a __. Likewise, __ and __are hydrolyzed slowly in the absence of a catalyst
    §  These molecules are __ in the face of a large thermodynamic driving force for reaction with O2 and H2O. The kinetic stability of these molecules in the absence of specific catalysts is essential for their biological function because it enables __. 
    NADH, NADPH, and FADH2

    O2 

    • catalyst
    • ATP and acetyl CoA 
    • kinetically stable
    • enzymes to control the flow of free energy and reducing power
  19. o   Most interchanges of activated groups in metabolism are accomplished by a __. The activated carriers are in all organisms
    ·         Almost all activated carriers are derived from __, which must be modified before it can serve its function
    ·         Higher organisms lost the capacity to synthesize them in the course of evolution
    • small set of carriers
    • vitamins
  20. ·         Not all vitamins function as coenzymes
    o   Vitamin A is the __
    o   Vitamin C acts as __
    o   A metabolite of vitamin D is a __
    o   Vitamin K is required for __
    • precursor of retinal (light sensitive group in rhodopsin), and retinoic acid, an important signaling molecule
    • an antioxidant
    • hormone that regulates the metabolism of calcium and phosphorus
    • normal blood clotting
  21. ·         The thousands of metabolic reactions can be subdivided into just six types

    1) ?
    oxidation reduction
  22. ·         The thousands of metabolic reactions can be subdivided into just six types

    2) ?
    o   Ligation reactions: form bonds by using free energy from ATP cleavage
  23. ·         The thousands of metabolic reactions can be subdivided into just six types

    3) ?
    o   Isomerization reactions rearrange particular atoms within a molecule. Their role is to prepare the molecule for subsequent reactions
  24. ·         The thousands of metabolic reactions can be subdivided into just six types

    4) ?
    o   Group-transfer reactions play a lot of roles
  25. ·         The thousands of metabolic reactions can be subdivided into just six types

    5) ?
    o   Hydrolytic reactions: cleave bonds by the addition of water; hydrolysis is a common means employed to break down large molecules, either to facilitate further metabolism or to reuse some of the components for biosynthetic purposes
  26. ·         The thousands of metabolic reactions can be subdivided into just six types

    6) ?
    o   Functional groups may be added to double bonds to form single bonds or removed from single bonds to form double bonds; lyases do this
  27. ·         These all can proceed in either direction, depending on the __ and the __
    ·         Metabolism must be __, as well as __, to adjust metabolic activity to the constantly changing external environments of cells. Metabolism is regulated through control of: ___
    • standard free energy for specific reaction
    • concentrations of the reactants and products inside the cell

    • regulated
    • flexible

    • amounts of enzymes
    • catalytic activity
    • accessibility of substrates
  28. o   Controlling the amounts of enzymes: amount depends on both __ and __; adjusted by a change in the __
    • rate of synthesis and rate of degradation
    • rate of transcription
  29. o   Controlling catalytic activity: can be controlled in many ways
    §  __ such as feedback inhibition
    §  __
    §  __coordinate metabolic relations between different tissues
    • Reversible allosteric control
    • Reversible covalent modification
    • Hormones
  30. §  Many reactions are controlled by the __. One index of the energy status is the __, which is proportional to the __ plus __, given that ATP contains __, whereas ADP contains one. 
    • energy status of the cell
    • energy charge
    • mole fraction of ATP
    • half the mole fraction of ADP
    • two anhydride bonds
  31. ·         The energy change can have a value ranging from 0 (all AMP) to 1 (al AATP)
    o   Daniel Atkinson showed that __ are inhibited by a high energy charge, whereas __ are stimulated by a high energy charge
    • ATP-generating (catabolic) pathways
    • ATP-utilizing (anabolic) pathways
  32. §  The energy charge, like the pH of a cell, is __. An alternative index of the energy status is the __, which depends on the __, and is directly related to the free-energy storage available from ATP
    • buffered
    • phosphorylation potential
    • concentration of Pi
  33. o   Controlling the accessibility of substrates: _ and __ are enhanced by __, which segregates opposed reactions
    §  Controlling the __ is another means of regulation
    • metabolic regulation and flexibility
    • compartmentalization
    • flux of substrates
  34. ·         Why do activated carriers have adenosine diphosphate units?
    o   Explanation one: they evolved from __; __ may have been recruited to serve as efficient carriers of activated electrons and chemical units
    o   When the more versatile proteins replaced __as the major catalysts, the __ stayed essentially unchanged because they were already suited to their metabolic roles
    o   With the advent of protein enzymes, these important __ evolved as free molecules without losing the __ vestige of their RNA world ancestry. 
    • early RNA catalysts
    • non-RNA units
    • RNA 
    • ribonucleotide coenzymes
    • cofactors
    • adenosine diphosphate

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