7 Bioenergy

enzyme

-ase

In cells, what is usually the immediate source of energy for an endergonic reaction? as spontaneous reactions, endergonic reactions do not need an addition of energy glucose sugar ADP ATP

ATP The hydrolysis of ATP provides the energy needed for an endergonic reaction.

What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule? hydrolysis anabolism entropic dehydration decomposition dehydration synthesis

Hydrolysis Hydrolysis involves breaking bonds with the addition of water.

other

allo-

across

trans-

Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions? α -phosphate (the phosphate closest to ribose) β-phosphate (the middle phosphate) γ-phosphate (the terminal phosphate) adenine group ribose sugar

γ-phosphate (the terminal phosphate) The γ-phosphate is the primary phosphate group on the ATP molecule that is hydrolyzed when energy is needed to drive anabolic reactions. Located the farthest from the ribose sugar, it has a higher energy than either the α- or β-phosphate.

change, turn, move

-trop-

Select the highest energy form of adenosine from the following images.

Adenosine triphosphate (ATP) is the high-energy form of adenosine because it contains the most phosphate groups (three). This molecule fuels many different endergonic (energy-requiring) enzymatic processes in biological organisms. ATP molecules diffuse or are transported to the place where the energy is needed and deliver chemical energy from the breaking of their phosphate bonds.

This graph illustrates a(n) _____ reaction. spontaneous exergonic hydrolysis endergonic catabolic

Endergonic The products contain more potential energy than the reactants.

Which of these reactions requires a net input of energy from its surroundings? exergonic endergonic ATP --> ADP + P catabolic hydrolysis

Endergonic The products of endergonic reactions have more potential energy than the reactants.

The reaction ADP + P --> ATP is a(n) _____ reaction. exergonic spontaneous endergonic hydrolysis chemical

Endergonic Energy has been acquired from the surroundings.

A(n) _____ reaction occurs spontaneously. endergonic kinetic anabolic exergonic chemical

Exergonic

The following reaction A --> B + C + heat is a(n) _____ reaction. anabolic exergonic dehydration synthesis exchange endergonic

Exergonic

The energy for an endergonic reaction comes from a(n) _____ reaction. synthesis glucose + glucose --> maltose ADP + P --> ATP exergonic anabolic

Exergonic The energy released by an exergonic reaction can be used to drive an endergonic reaction.

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _______ is to _______. exergonic; endergonic work; energy free energy; entropy exergonic; spontaneous entropy; enthalpy

Exergonic; endergonic

What is the fate of the phosphate group that is removed when ATP is converted to ADP? It is broken down into one phosphorus and four oxygen atoms. It is acquired by a reactant in an endergonic reaction. It is used to convert an ATP into an AQP. It is acquired by a reactant in a spontaneous reaction. It is acquired by a reactant in an exergonic reaction.

It is acquired by a reactant in an endergonic reaction.

Most cells cannot harness heat to perform work because heat is not a form of energy. heat can never be used to do work . cells do not have much heat; they are relatively cool. temperature is usually uniform throughout a cell. heat must remain constant during work.

Temperature is usually uniform throughout a cell

Which of the following statements about the role of ATP in cell metabolism is true? The phosphate bonds of ATP are unusually strong bonds. The energy from the hydrolysis of ATP may be directly coupled to endergonic processes by the transfer of the phosphate group to another molecule. The free energy released by ATP hydrolysis has a much more negative ΔG value than the hydrolysis of phosphate groups from other phosphorylated molecules.

The energy from the hydrolysis of ATP may be directly coupled to endergonic processes by the transfer of the phosphate group to another molecule. ______ A key feature in the way cells manage their energy resources to do this work is energy coupling, the use of an exergonic process to drive an endergonic one. ATP is responsible for mediating most energy coupling in cells, and in most cases it acts as the immediate source of energy that powers cellular work. Read about energy coupling.

What is the free energy change (ΔG) of the hydrolysis of ATP to ADP? The free-energy change (ΔG) of the hydrolysis of ATP to ADP and Pi may vary considerably with variations in pH, temperature, atmospheric pressure, and concentrations of reactants and products. The free-energy change (ΔG) of the hydrolysis of ATP to ADP and Pi is approximately -7.3 kcal/mole, but it varies from species to species. The free-energy change (ΔG) of the hydrolysis of ATP to ADP and Pi is constant at -7.3 kcal/mole.

The free-energy change (ΔG) of the hydrolysis of ATP to ADP and Pi may vary considerably with variations in pH, temperature, atmospheric pressure, and concentrations of reactants and products. ____ The free-energy change (ΔG) of the hydrolysis of ATP to ADP and Pi is -7.3 kcal/mole under standard conditions. Standard conditions are defined as a temperature of 298 K (or 250C), 1 atm, pH 7, and equal 1M concentrations present of all reactants and products. In living cells, conditions do not conform to standard conditions, primarily because reactant and product concentrations differ from 1 M. For example, when ATP hydrolysis occurs under cellular conditions, the actual ΔG is about -13 kcal/mol, 78% greater than the energy released by ATP hydrolysis under standard conditions.

Heat

Therm-

Select the INCORRECT association. enzyme ... protein exergonic ... spontaneous potential energy ... positional energy kinetic energy ... motion exergonic ... uphill

exergonic ... uphill Exergonic reactions release energy.

Outside of:

extra

sweet

glyc-

In this reaction _____. heat has been released to the environment the chemical energy of the products is greater than that of the reactants entropy has decreased disorder has decreased the kinetic energy of the reactants is less than that of the products

heat has been released to the environment

moving

kin- (or kinet-

milk

lac- (lact-)

Under, below

sub-

In this reaction _____. the products have been rearranged to form reactants CD is a product the products have less potential energy than the reactants entropy has decreased AC is a reactant

the products have less potential energy than the reactants

What is energy coupling? the hydrolysis of ATP to ADP + P a description of the energetic relationship between the reactants and products in an exergonic reaction a barrier to the initiation of a reaction the use of an enzyme to reduce EA the use of energy released from an exergonic reaction to drive an endergonic reaction

the use of energy released from an exergonic reaction to drive an endergonic reaction