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Intro to Phosphate Anhydrides quiz

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  • What is a phosphate anhydride?
    A phosphate anhydride consists of two or more phosphate groups linked together, typically formed by condensation reactions.
  • How is pyrophosphoric acid formed?
    Pyrophosphoric acid is formed by the condensation of two phosphoric acid molecules, with the loss of water.
  • What happens to the hydroxyl groups in pyrophosphoric acid in its acidic form?
    In its acidic form, the hydroxyl groups of pyrophosphoric acid are protonated.
  • What is the predominant form of pyrophosphate in biological systems?
    In biological systems, pyrophosphate predominates in its deprotonated form with negative oxygens due to the slightly basic pH.
  • What is the pH of most biological systems where pyrophosphate is found?
    Most biological systems have a slightly basic pH, around 7.4.
  • Which molecule is the most important example of a phosphate anhydride in biology?
    ATP (Adenosine Triphosphate) is the most important and common phosphate anhydride in biology.
  • What is the difference between ATP and ADP?
    ATP has three phosphate groups, while ADP (Adenosine Diphosphate) has two, having lost one phosphate group.
  • What happens during a nucleophilic attack on an alkylated phosphate anhydride?
    A nucleophile attacks the alpha carbon, causing carbon-oxygen bond cleavage and producing a pyrophosphate ion and an alkylated nucleophile.
  • What are the products of nucleophilic attack on an alkylated phosphate anhydride?
    The products are a pyrophosphate ion and an alkylated nucleophile.
  • Which carbon is attacked by the nucleophile in an alkylated phosphate anhydride?
    The nucleophile attacks the alpha carbon, which is the carbon directly attached to the oxygen of the phosphate group.
  • Is the nucleophilic attack on alkylated phosphate anhydrides reversible or irreversible?
    The reaction is reversible unless an enzyme-catalyzed nucleophilic acyl substitution occurs, making it irreversible.
  • How can the reaction involving pyrophosphate be made irreversible?
    The reaction becomes irreversible if an enzyme catalyzes a nucleophilic acyl substitution of the pyrophosphate ion.
  • What is the role of pyrophosphate in the reversibility of the reaction?
    Pyrophosphate can act as a nucleophile and reverse the reaction by attacking the alpha carbon, unless it is consumed in a subsequent reaction.
  • What is an anhydride in general organic chemistry?
    An anhydride is a compound with two acyl groups bonded to the same oxygen atom, typically formed from the condensation of two acids.
  • How does a phosphate anhydride differ from a typical anhydride?
    A phosphate anhydride has phosphorus atoms in place of the carbonyl carbons found in typical anhydrides.