Practice Test: Biochemistry Chapter 3

Matching skip

Short Answer skip

1. Gibbs free energy equation
   
2. negentropy
   
3. chemotrophic organisms
   
4. closed system
   
5. three kinds of systems
   

Multiple Choice skip

1. entropy
   1. open
   2. Portion of the universe with which we are concerned
   3. Effects of concentration much greater than effects of protons or metal ions under physiological conditions.
   4. Measure of disorder and randomness in the system. Organized or ordered state is low-entropy.
   5. Experimentally determines enthalpy changes for biochemical processes.
2. energy dispersion
   1. G = H - TS. At constant pressure and temperature: ∆G = ∆H - T∆S.
   2. What entropy represents, the dispersion of energy among a large number of molecular motions relatable to quantized states (microstates)
   3. Cannot exchange matter or energy with its surroundings
   4. Unpaired electrons of bridging oxygen in acetic anhydride can’t participate in resonance structures.
   5. Carbonyl groups withdraw e- density Adjacent acetyl groups destabilize each other, fighting for e- density Phosphorous also e- withdrawing, destabilize the potential for PPi or P2O7 2- from forming. In addition, if this were to happen, reformation of ATP would require the repulsion of these anions to be overcome
3. In real life, how do metal ions affect free energy of hydrolysis of ATP?
   1. free energy of hydrolysis of ATP altered more by metal ions that protons
   2. mixed anhydrides of phosphoric and carboxylic acids. Energy rich. Hydrolysis leads to inorganic phosphates. Large ∆Gº’ from bond strain: partial positive charges on carbonyl carbon and phosphorus atoms of these structures. Energy stored in mixed anhydride bond released upon hydrolysis. Value of ∆Gº’ depends on pKa of starting anydride and product phosphate and carboxylic acids.
   3. No bearing
   4. ∆E = E2 - E1 = q + w Where q: The heat absorbed by the system from the surroundings. w: the work done on the system by the surroundings.
   5. ∆E = heat transferred in a constant volume system. ∆H = heat transferred in a constant pressure process. Often essentially equal though, because volume changes are typically quite small.
4. What are the 3 chemical reasons for large negative ∆Gº values in pyrophosphoryl/phosphoric acid anhydride linkages
   1. the process is at equilibrium and there is no net flow either in the forward or reverse direction.
   2. Destabilization of reactant due to bond strain caused by electrostatic repulsion, stabilization of the products by ionization and resonance, and entropy factors due to hydrolysis and subsequent ionization.
   3. sum free energy changes for each reaction.
   4. Unpaired electrons of bridging oxygen in acetic anhydride can’t participate in resonance structures.
   5. Gibbs free energy, G. Any process with nonzero ∆G proceeds spontaneously to a final state of lower free energy. (Whichever writing of the equation makes ∆G negative)
5. describe the stabilization of hydrolysis products by ionization and resonance in pyrophosphoryl/phosphoric acid anhydride linkages
   1. The free energy change that occurs upon hydrolysis, that is, upon transfer of a particular group to water. In many reactions, a functional group is transferred from a donor molecule to a specific receptor molecule or water. Explains the tendency for reactions to occur. Analogous to those of ionization potential and reduction potential. Release of free energy that occurs upon the hydrolysis of ATP and other “high-energy phosphates” treated quantitatively in terms of group transfer.
   2. For solutes in a solution, standard state is normally unit activity (often simplified to 1 M concentration) Symbolized by “º”.
   3. Total energy of an isolated system is conserved. All forms of energy could ultimately be converted to some other form.
   4. By itself, pyrophosphoryl moiety has two negative charges at pH of above 7.5 Hydrolysis product, two phosphate esters, each carry two negative charges (pH above 7.2) Increased ionization stabilizes the electrophilic phosphorous nuclei
   5. large positive

True or False skip

1. system
   Portion of the universe with which we are concerned

   True   False

2. What is the equation for w?
   w = -P∆V where P is the pressure and ∆V is the volume change and is equal to V2 - V1.

   True   False

3. How does ATP rank as a high-energy phosphate?
   the process is at equilibrium and there is no net flow either in the forward or reverse direction.

   True   False

4. How do you find the ∆Gº when pH is involved?
   (E or U) Includes all the energies that might be exchanged in physical or chemical processes. Eg. rotational, vibrational, translational energies of molecules and also energy stored in covalent and noncovalent bonds.

   True   False

5. high-energy compound
   open

   True   False