BioloChap8
Which of the following is a chemical reaction?
A chemical reaction alters the covalent bonding between atoms, making new kinds of molecules. That doesn't happen in any of the events listed here.
Which of the following statements is not true of most cellular redox reactions?
A hydrogen atom is transferred to the atom that loses an electron. (A hydrogen atom (proton, or H+) is often transferred to the atom that gains an electron.)
In cells, what is usually the immediate source of energy for an endergonic reaction?
ATP andThe hydrolysis of ATP provides the energy needed for an endergonic reaction.
You have an enzymatic reaction proceeding at the optimum pH and optimum temperature. You add a competitive inhibitor to the reaction and notice that the reaction slows down.
Add more substrate; it will outcompete the inhibitor and increase the reaction rate.
Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?
Anion and cation.
What will happen to the rates of the forward and reverse reactions when a catalyst is added?
Both forward and reverse rates increase.
Which fact is most important in explaining how molecules convert thermal energy to activation energy (EA)?
Distortion increases a molecule's potential energy.
Which term describes the degree to which an element attracts electrons?
Electronegativity.
Which of these reactions requires a net input of energy from its surroundings?
Endergonic and The products of endergonic reactions have more potential energy than the reactants.
A(n) _____ reaction occurs spontaneously
Exergonic and In exergonic reactions the products have less potential energy than the reactants.
Which molecule is oxidized and what kind of bond is formed?
Hydrogen, polar.
A reaction is said to be unfavorable if ...
If the free energy change for the reaction is positive, equilibrium favors the reactants and we say the reaction is unfavorable.
Consider a situation in which the enzyme is operating at optimum temperature and pH, and has been saturated with substrate. What is your best option for increasing the rate of the reaction?
Increase the enzyme concentration.
What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?
Ionic.
Which statement is true of the transition state?
It can break apart to yield either reactants or products and It is extremely unstable and lasts only an instant.
What is the fate of the phosphate group that is removed when ATP is converted to ADP?
It is acquired by a reactant in an endergonic reaction. (By acquiring the phosphate group the reactant acquires energy.)
Which of the following is true of activation energy?
Molecules usually get it from thermal energy.
Which of the following statements is true of the bonds in a water molecule?
Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.
Which of the following statements is most likely to be true in the case of the feedback-regulated enzymatic pathway shown?
P4 binds E1 and deactivates it.
How do cells replace the energy-rich ATP that is destroyed in energy-coupled reactions?
Plants have both chloroplasts and mitochondria. Animals lack chloroplasts; they get sugars and fats from other organisms to fuel their mitochondria.
Which type of control agent exerts noncompetitive inhibition?
Protein kinase and Allosteric effecto
Which type of control agent never speeds an enzyme's action?
Substrate analog
You have added an irreversible inhibitor to a sample of enzyme and substrate. At this point, the reaction has stopped completely.
The enzyme is inactive at this point. New enzyme must be added to regain enzyme activity.
What would happen to the rate of the forward reaction if the concentration of nitrogen were decreased?
The reaction rate would decrease .
The Haber process is typically carried out at a temperature of approximately 500∘C. What would happen to the rate of the forward reaction if the temperature were lowered to 100∘C?
The reaction rate would decrease and Most reactions double in rate for each 10∘C increase in temperature.
How do cells use ATP to raise the energy level of reaction substrates?
The terminal phosphate of ATP is bound to the substrate.
The reaction A → B is unfavorable by itself, but through energy-coupling, cells can use ATP to convert A into B. How is this done?
The unfavorable reaction is replaced by two favorable reactions and The first reaction transfers part of ATP to A, making a high-energy product. That product is then converted to B. Both reactions release energy, so both are favorable.
Which statement is characteristic of allosteric effectors?
They may not resemble the enzyme's substrates
Why is ATP a good source of energy for biological reactions?
Triphosphate chains are unstable. (The instability is associated with high energy, favoring reactions that break the triphosphate chain.)
Which of these is exhibiting kinetic energy?
a space station orbiting Earth and Kinetic energy is energy of motion.
Potential energy is always ...
associated with position or arrangement.
In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?
cellular respiration and This is the name given to the process by which the body converts food energy to energy stored in ATP.
The reaction ADP + P --> ATP is a(n) _____ reaction.
endergonic and Energy has been acquired from the surroundings.
"Conservation of energy" refers to the fact that _____.
energy cannot be created or destroyed but can be converted from one form to another
The energy for an endergonic reaction comes from a(n) _____ reaction.
exergonic and The energy released by an exergonic reaction can be used to drive an endergonic reaction.
Which of these are by-products of cellular respiration?
heat, carbon dioxide, and water (These are the by-products of cellular respiration.)
What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?
hydrolysis (Hydrolysis involves breaking bonds with the addition of water.)
In cooperativity, .
if one substrate is bound, the next binds more easily.
Which of the following would increase the rate of the reverse reaction?
increasing the concentration of ammonia and The concentration of NH3 affects how quickly N2 and H2 can be made
An enzyme _____.
is an organic catalyst and Enzymes are proteins that behave as catalysts.
As a result of its involvement in a reaction, an enzyme _____.
is unchanged and Enzymes are not changed as a result of their participation in a reaction.
Chemical energy is a form of _____ energy.
potential and Chemical energy is a form of stored energy.
In general, enzymes are what kinds of molecules?
proteins and Enzymes are proteins.
Enzymes work by _____.
reducing EA and Enzymes work by reducing the energy of activation.
What name is given to the reactants in an enzymatically catalyzed reaction?
substrate and This is the name given to the reactants in an enzymatically catalyzed reaction.
What is energy coupling?
the use of energy released from an exergonic reaction to drive an endergonic reaction
Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions?
γ-phosphate (the terminal phosphate) and The γ-phosphate is the primary phosphate group on the ATP molecule that is hydrolyzed when energy is needed to drive anabolic reactions
