BIOC 385 - exam I question with
complete solutions
What must be constant for a living organism to maintain a homeostatic condition that is far
from equilibrium? - correct answer ✔✔constant input of energy
What do living systems abide by? - correct answer ✔✔the Laws of Thermodynamics; the
spontaneity of biochemical reactions is expressed as ΔGo' in kJ/mol
energy charge - correct answer ✔✔a measure of [ATP], [ADP], and [AMP] in the cell and reflects
the amount of ATP for metabolic reactions
The energy available from redox reactions due to what? - correct answer ✔✔differences in the
electron affinity of two compounds and is an inherent property of each molecule based on
molecular structure
What are the two half reactions of a redox reaction? - correct answer ✔✔1) oxidation reaction
(loss of electrons)
2) reduction reaction (gain of electrons)
What type of enzymes catalyze a redox reaction? - correct answer ✔✔enzymes that permit the
energy to be captured as work
What do photosynthetic autotrophs use energy from sunlight for? - correct answer ✔✔to
photooxideize biomolecules that initiate redox reactions using electrons supplied from H2O to
interconvert chemical energy and generate ATP
,What do photosynthetic autotrophs and heterotrophs interconvert? - correct answer
✔✔chemical energy using redox reactions to generate ATP from carbohydrates
NAD, FAD, and quinone are examples of what? - correct answer ✔✔electron carriers in
numerous biochemical reactions
first law of thermodynamics - correct answer ✔✔the total amount of energy in the universe
does not change; energy can neither be created or destroyed. Energy conversion in biological
systems is never 100% with the remainder of energy released often as heat
second law of thermodynamics - correct answer ✔✔in the absence of energy input, all natural
processes in the universe tend toward disorder, which is a measure of entropy (S). In chemical
terms entropy is the dispersion of energy; how energy is spread out (motion)
Gibbs free energy (g) and Equilibrium Constant (Keq) - correct answer ✔✔In the reaction A-->B,
ΔG = ΔGo'+ RT • ln [B]equilibrium / [A]equilibrium
or
ΔGo' = -RTlnKeq
What direction does the reaction go if Keq > 1? - correct answer ✔✔the reaction proceeds
spontaneously to form C and D (left to right as written), then the value for ΔGo is negative
What direction does the reaction go if Keq < 1? - correct answer ✔✔the reaction favors the
formation of A and B (right to left as written), then the value of ΔGo is positive in this case
How can an unfavorable reaction proceed in vivo? - correct answer ✔✔unfavorable and
favorable reactions are coupled in vivo by sharing a common intermediate; the product of one
,reaction is the reactant in a coupled reaction. An exergonic reaction (favorable) coupled to an
endergonic reaction (unfavorable) is an energetically favorable reaction
The ΔGo value for the coupled reactions is equal to? - correct answer ✔✔the sum of the ΔGo
values for the two separate reactions
What happens to the two phosphoanhydride bonds contained in ATP? - correct answer ✔✔can
be hydrolyzed to yield adenosine diphosphate and inorganic phosphate (ADP + Pi) or adenosine
monophosphate and pyrophosphate (AMP + PPi)
Very often when the transfer of a phosphoric or AMP group to react generates what? - correct
answer ✔✔a highly reactive intermediate
Two examples of cases in which phosphoanhydride bond hydrolysis does promote biochemical
process are usually related to protein conformational changes that accompany ATP and ATP
hydrolysis - correct answer ✔✔muscle contraction and ion transport against a concentration
gradient
What is the energy charge range maintained by a cell? - correct answer ✔✔between 0.7 and 0.9
as a result of regulated flux through anabolic and catabolic pathways
What are the primary factors that determine the flow or flux of metabolites through catabolic
and anabolic pathways? - correct answer ✔✔1) Availability of substrates (diet or stored
reserves)
2) Level of enzyme activity: enzyme levels (gene transcription, protein synthesis); catalytic
activity (allosteric control, covalent modification); compartmentation (subcellular or tissue
localization)
What are the four classes of macromolecules? - correct answer ✔✔proteins, nucleic acids,
carbohydrates, and lipids
, What are the six primary metabolite groups? - correct answer ✔✔amino acids, nucleotides,
fatty acids, glucose, pyruvate, acetyl CoA
What are the seven small biomolecules? - correct answer ✔✔NH4+, CO2, NADH, FADH2, O2,
ATP, H2O
enzymes - correct answer ✔✔are a biological catalysts that alter reaction rates without
changing the overall change in free energy (ΔG) of the equilibrium constant (Keq) of the
reaction
transition state theory - correct answer ✔✔states that a reactant must reach an energy level
required for chemical transformation before product can be formed; enzymes lower the
activation energy
What do cofactors and coenzymes provide? - correct answer ✔✔additional reactive group to
the enzyme active site that complement limited chemistry of amino acid side chains; cofactors
are inorganic ions whereas coenzymes are small organic compounds often derived from
vitamins.
What does an enzyme active site provide? - correct answer ✔✔provide chemical environments
that facilitate catalytic reactions by excluding excess solvent the reactive functional groups of
the enzyme into close proximity to the substrate
What is an example fo the induced-fit model of enzyme catalysis? - correct answer ✔✔glycolytic
enzyme hexokinase, which undergoes a large conformational change upon binding of the
glucose substrate
What increased the catalytic efficiency of glycogen phosphorylase? - correct answer
✔✔noncovalent binding of allosteric regulators, such as AMP, and by covalent attachment of a
phosphoryl group to Ser14
complete solutions
What must be constant for a living organism to maintain a homeostatic condition that is far
from equilibrium? - correct answer ✔✔constant input of energy
What do living systems abide by? - correct answer ✔✔the Laws of Thermodynamics; the
spontaneity of biochemical reactions is expressed as ΔGo' in kJ/mol
energy charge - correct answer ✔✔a measure of [ATP], [ADP], and [AMP] in the cell and reflects
the amount of ATP for metabolic reactions
The energy available from redox reactions due to what? - correct answer ✔✔differences in the
electron affinity of two compounds and is an inherent property of each molecule based on
molecular structure
What are the two half reactions of a redox reaction? - correct answer ✔✔1) oxidation reaction
(loss of electrons)
2) reduction reaction (gain of electrons)
What type of enzymes catalyze a redox reaction? - correct answer ✔✔enzymes that permit the
energy to be captured as work
What do photosynthetic autotrophs use energy from sunlight for? - correct answer ✔✔to
photooxideize biomolecules that initiate redox reactions using electrons supplied from H2O to
interconvert chemical energy and generate ATP
,What do photosynthetic autotrophs and heterotrophs interconvert? - correct answer
✔✔chemical energy using redox reactions to generate ATP from carbohydrates
NAD, FAD, and quinone are examples of what? - correct answer ✔✔electron carriers in
numerous biochemical reactions
first law of thermodynamics - correct answer ✔✔the total amount of energy in the universe
does not change; energy can neither be created or destroyed. Energy conversion in biological
systems is never 100% with the remainder of energy released often as heat
second law of thermodynamics - correct answer ✔✔in the absence of energy input, all natural
processes in the universe tend toward disorder, which is a measure of entropy (S). In chemical
terms entropy is the dispersion of energy; how energy is spread out (motion)
Gibbs free energy (g) and Equilibrium Constant (Keq) - correct answer ✔✔In the reaction A-->B,
ΔG = ΔGo'+ RT • ln [B]equilibrium / [A]equilibrium
or
ΔGo' = -RTlnKeq
What direction does the reaction go if Keq > 1? - correct answer ✔✔the reaction proceeds
spontaneously to form C and D (left to right as written), then the value for ΔGo is negative
What direction does the reaction go if Keq < 1? - correct answer ✔✔the reaction favors the
formation of A and B (right to left as written), then the value of ΔGo is positive in this case
How can an unfavorable reaction proceed in vivo? - correct answer ✔✔unfavorable and
favorable reactions are coupled in vivo by sharing a common intermediate; the product of one
,reaction is the reactant in a coupled reaction. An exergonic reaction (favorable) coupled to an
endergonic reaction (unfavorable) is an energetically favorable reaction
The ΔGo value for the coupled reactions is equal to? - correct answer ✔✔the sum of the ΔGo
values for the two separate reactions
What happens to the two phosphoanhydride bonds contained in ATP? - correct answer ✔✔can
be hydrolyzed to yield adenosine diphosphate and inorganic phosphate (ADP + Pi) or adenosine
monophosphate and pyrophosphate (AMP + PPi)
Very often when the transfer of a phosphoric or AMP group to react generates what? - correct
answer ✔✔a highly reactive intermediate
Two examples of cases in which phosphoanhydride bond hydrolysis does promote biochemical
process are usually related to protein conformational changes that accompany ATP and ATP
hydrolysis - correct answer ✔✔muscle contraction and ion transport against a concentration
gradient
What is the energy charge range maintained by a cell? - correct answer ✔✔between 0.7 and 0.9
as a result of regulated flux through anabolic and catabolic pathways
What are the primary factors that determine the flow or flux of metabolites through catabolic
and anabolic pathways? - correct answer ✔✔1) Availability of substrates (diet or stored
reserves)
2) Level of enzyme activity: enzyme levels (gene transcription, protein synthesis); catalytic
activity (allosteric control, covalent modification); compartmentation (subcellular or tissue
localization)
What are the four classes of macromolecules? - correct answer ✔✔proteins, nucleic acids,
carbohydrates, and lipids
, What are the six primary metabolite groups? - correct answer ✔✔amino acids, nucleotides,
fatty acids, glucose, pyruvate, acetyl CoA
What are the seven small biomolecules? - correct answer ✔✔NH4+, CO2, NADH, FADH2, O2,
ATP, H2O
enzymes - correct answer ✔✔are a biological catalysts that alter reaction rates without
changing the overall change in free energy (ΔG) of the equilibrium constant (Keq) of the
reaction
transition state theory - correct answer ✔✔states that a reactant must reach an energy level
required for chemical transformation before product can be formed; enzymes lower the
activation energy
What do cofactors and coenzymes provide? - correct answer ✔✔additional reactive group to
the enzyme active site that complement limited chemistry of amino acid side chains; cofactors
are inorganic ions whereas coenzymes are small organic compounds often derived from
vitamins.
What does an enzyme active site provide? - correct answer ✔✔provide chemical environments
that facilitate catalytic reactions by excluding excess solvent the reactive functional groups of
the enzyme into close proximity to the substrate
What is an example fo the induced-fit model of enzyme catalysis? - correct answer ✔✔glycolytic
enzyme hexokinase, which undergoes a large conformational change upon binding of the
glucose substrate
What increased the catalytic efficiency of glycogen phosphorylase? - correct answer
✔✔noncovalent binding of allosteric regulators, such as AMP, and by covalent attachment of a
phosphoryl group to Ser14
