A space station orbiting Earth is exhibiting:
kinetic energy
“Conservation of energy” refers to the fact that _____.
energy cannot be created or destroyed but can be converted from one form to another
Chemical energy is a form of _____ energy.
potential
In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?
cellular respiration
Which of these are by-products of cellular respiration?
heat, carbon dioxide, and water
In general, enzymes are what kinds of molecules?
proteins
Enzymes work by _____.
reducing EA (activation energy)
An enzyme _____.
is an organic catalyst
What name is given to the reactants in an enzymatically catalyzed reaction?
substrate
As a result of its involvement in a reaction, an enzyme _____.
is unchanged
What is the correct label for “A”?
energy of activation
Ammonia is used in numerous industrial processes, including the production of pharmaceuticals such as sulfonamide and antimalarials and vitamins such as the B vitamins. The equilibrium equation for the synthesis of ammonia (sometimes known as the Haber process) is
(image)
The Haber process is typically carried out at a temperature of approximately 500. What would happen to the rate of the forward reaction if the temperature were lowered to 100?
The reaction rate would decrease.
What would happen to the rate of the forward reaction if the concentration of nitrogen were decreased?
The reaction rate woulddecrease.
Which of the following would increase the rate of the reverse reaction?
increasing the concentration of ammonia
What will happen to the rates of the forward and reverse reactions when a catalyst is added?
Both forward and reverse rates increase.
Most product formed?
reaction catalyzed by enzyme B
Neither most nor least product formed?
reaction catalyzed by enzyme A
Least product formed?
uncatalyzed reaction
An enzyme is ___ when it loses its native conformation and its biological activity.
denatured
An enzyme is considered a ___ because it speeds up chemical reactions without being used up.
catalyst
An enzyme is considered ___ because of its ability to recognized the shape of a particular molecule.
specific
A ___, such as a vitamin, binds to an enzyme and plays a role in catalysis.
cofactor
When properly aligned, the enzyme and the substrate form an enzyme-subrate (ES) ___.
complex
A substrate binds to an enzyme at the ___, where the reaction occurs.
active site
In a catalyzed reaction, a reactant is often called the ___.
substrate
Select the highest energy form of adenosine from the following images.
ATP adenosine triphosphate, contains most phosphate groups
Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions?
lambda-phosphate (the terminal phosphate)
In this reaction _____.
the products have less potential energy than the reactants and heat has been released to the environment
The reaction A –> B + C + heat is released in a(n) _____ reaction.
exergonic
A(n) _____ reaction occurs spontaneously.
exergonic
Which of these reactions requires a net input of energy from its surroundings?
endergonic
In cells, what is usually the immediate source of energy for an endergonic reaction?
ATP
The reaction ADP
P –> ATP is a(n) _____ reaction.~endergonic
The energy for an endergonic reaction comes from a(n) _____ reaction.
exergonic
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.
This graph illustrates a(n) _____ reaction.
endergonic
motion
kinetic energy
protein
enzyme
nonspontaneous
endergonic
spontaneous
exergonic
positional energy
potential energy
What is the use of energy released from an exergonic reaction to drive an endergonic reaction?
energy coupling
In which region does the reaction rate remain constant?
region C
In which region is the enzyme saturated with substrate?
region C
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.
The image shows a hypothetical enzymatic pathway with four enzymes, labeled E1, E2, E3, and E4. The enzymes make products, labeled P0, P1, P2, P3, and P4. 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.
All ___ reactions proceeds with a net release of free energy.
exergonic
A chemical reaction that has a positive is correctly described as
endergonic
When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?
It is lost to the environment.
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction’s
activation energy.
A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because
the activation energy barrier for this reaction cannot be surmounted.
During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the for the new reaction?
-20 kcal/mol
___ increase the rate of chemical reaction by lowering activation energy barriers.
Enzymes
Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid. What is the purpose of using malonic acid in this experiment?
It is a competitive inhibitor.
Which of the following terms best describes the reaction?
exergonic
Which of the following represents the activation energy required for the enzyme-catalyzed reaction?
b
In order to attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur in order for the final attachment to occur?
The binding of the first two molecules must cause a 3-dimensional change that opens another active site on the enzyme.
How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?
by changing the shape of an enzyme
A series of enzymes catalyze the reaction . Product binds to the enzyme that converts to at a position remote from its active site. This binding decreases the activity of the enzyme.
Substance functions as
an allosteric inhibitor.
Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?
As a consequence of growing, organisms create more disorder in their environment than the decrease in entropy associated with their growth.
A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases although they don’t often hydrolyze ATP unless they are simultaneously transporting ions. Because small increases in calcium ions in the cytosol can trigger a number of different intracellular reactions, cells keep the cytosolic calcium concentration quite low under normal conditions, using ATP-powered calcium pumps. For example, muscle cells also transport calcium from the cytosol into the membranous system called the sarcoplasmic reticulum (SR). If a resting muscle cell’s cytosol has a free calcium ion concentration of 10-7, while the concentration in the SR is 10-2, then how is the ATPase acting?
ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient.
x

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