Energy and Enzymes

The active site of an enzyme is the region that

is involved in the catalytic reaction of the enzyme.

Catabolic Pathway

degradative process that generates energy as an end product

Which of the following terms best describes the forward reaction in the figure?

exergonic, ΔG < 0

Anabolic Pathway

energy consuming process that builds more complex molecules from simpler ones

Which of the following represents the difference between the free-energy content of the reactants and the free-energy content of the products in the figure?

d

What is energy?

the capacity to do work, and capacity to cause change.

Which of the following is true for all exergonic reactions?

The reaction proceeds with a net release of free energy.

Kinetic Energy

energy associated with movement (includes thermal energy)

Which of the following represents the activation energy required for the enzyme-catalyzed reaction in the figure?

b

Potential energy

stored energy that can potentially be converted to another form of energy and do work

Which curve(s) on the graphs may represent the temperature and pH profiles of an enzyme taken from a bacterium that lives in a mildly alkaline hot springs at temperatures of 70°C or higher?

curves 3 and 5

Chemical Energy

may be stored as form of potential in a molecule

Which of the following statements is true about enzyme-catalyzed reactions?

The reaction is faster than the same reaction in the absence of the enzyme.

Second of Thermodynamics

every energy transfer or transformation increases the disorder of the universe

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 easily be surmounted at room temperature.

Spontaneous (Gibbs)

the process will run without an outside input of energy (Delta G is negative)

In a spontaneous change

the system becomes more stable, the released free energy can be harnessed to do work

When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?

It is lost to the environment.

ATP (Adenosine Tri-phosphate)

produced by cellular respiration (breaking down of glucose leads to energy release that drive ATP synthesis which is endergonic)

Which of the following statements is true concerning catabolic pathways?

They supply energy, primarily in the form of ATP, for the cell's work.

Hydrolysis of ATP

Exergonic reaction

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as is to .

exergonic; endergonic

How does ATP power cellular work

Energy coupling mechanism (the use of an exergonic process to drive an endergonic one) Hydrolysis of ATP releases energy that can drive endergonic reactions (breaking of high energy bond between phosphates in ATP releases energy)

Catalyst

a chemical agent that speeds up a reaction without being consumed by the reaction

Which of the following statements regarding enzymes is true?

Enzymes increase the rate of a reaction by lowering the activation energy barrier.

Activation Energy Barrier

chemical reaction involves bond breaking and bond forming. A major factor in determining the rate of a particular reaction

Substrate

the molecule that an enzyme acts on.

Which of the following types of reactions would decrease the entropy within a cell?

anabolic reactions

Coenzyme

organic such as vitamins

Cofactors

inorganic such as metals

Which of the following is true for all exergonic reactions?

The reaction proceeds with a net release of free energy

Enzyme inhibitors

molecules taht selectively interfere with the action of specific enzymes

Enzyme inhibitors

molecules taht selectively interfere with the action of specific enzymes

Enzyme Inhibition is necessary to…

regulate proper level of substrates being produced

Which of the following best describes enthalpy (H)?

the heat content of a chemical system

competitive inhibitor

mimics the substrate competing for the active site

Which of the following statements is true about enzyme-catalyzed reactions?

The reaction is faster than the same reaction in the absence of the enzyme.

Noncompetitve inhibitor

binds to the enzyme away from the active site altering the conformation of the enzyme so that its active site no longer functions

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?

competitive inhibition

How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?

by changing the shape of the enzyme's active site

If the entropy of a living organism is decreasing what is occuring simultaneously?

Energy input into the organism must be occuring to drive the decrease in entropy

When one molecule is broken down into 6 component molecules what is true?

delta S is positive

Above a certain substrate concentration, the rate of an enzyme-catalyzed reaction drops as the enzymes become saturated. What would lead to a faster conversion of substrate into product under these saturated conditions?

Either increasing the enzyme concentration or slightly increasing the temperature will increase the rate of product formation.

Enzyme activity is affected by pH because _.

high or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the active site

The binding of an allosteric inhibitor to an enzyme causes the rate of product formation by the enzyme to decrease. Why does this decrease occur?

The allosteric inhibitor causes a structural change in the enzyme that prevents the substrate from binding at the active site.

When you have a severe fever, what grave consequence may occur if the fever is not controlled?

change in the tertiary structure of your enzymes

If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to

add more of the enzyme.

How does an enzyme increase the rate of the chemical reaction it catalyzes?

An enzyme reduces the free energy of activation (EA) of the reaction it catalyzes. (An enzyme catalyzes a reaction by lowering EA, enabling the reactant molecules to absorb enough energy to reach the transition state even at moderate temperatures.)