Chapter 5 Energy Flow in the Life of a Cell

Question 1

Activation Energy

Answer 1

In a chemical reaction, the energy needed to force the electron shells of reactants together, before the formation of products.

Question 2

Active Site

Answer 2

The region of an enzyme molecule that binds substrates and performs the catalytic function of the enzyme.

Question 3

Adenosine Diphosphate (ADP)

Answer 3

A molecule composed of the sugar ribose, the base adenine, and two phosphate groups; a component of ATP.

Question 4

Adenosine Triphosphate (ATP)

Answer 4

A molecule composed of the sugar ribose, the base adenine, and three phosphate groupsl thge major energy carrier in cells. The last two phosphate groups are attached by “high-energy” bonds.

Question 5

Allosteric Regulation

Answer 5

The process by which enzyme action is enhanced or inhibited by small organic molecules that act as regulators by binding to the enzyme and altering its active site.

Question 6

Catalyst

Answer 6

A substance that speeds up a chemical reaction without itself being permanently changed in the process; lowers the activation energy of reaction.

Question 7

Chemical Reaction

Answer 7

The process that forms and breaks chemical bonds that hold atoms together.

Question 8

Competitive Inhibition

Answer 8

The prcoess by which two or more molecules that are somewhat similar in structure compete for the active site of an enzyme.

Question 9

Coupled Reaction

Answer 9

A pair of reaction, one exergonic and one endergonic, that are linked together such that energy proiduced by the exergonic reaction proivides the energy needed to drive the endergonic reaction.

Question 10

Electron Carrier

Answer 10

A molecule that can reversibly gain or lose electrons. Electron carriers generally accept high-energy electons produced during an exergonic reaction and donate the electrons to acceptor molecules that use the energy to drive endergonic reactions.

Question 11

Endergonic Reaction

Answer 11

A chemical reaction that requires an input of energy to proceed.

Question 12

Energy

Answer 12

The capacity to do work.

Question 13

Energy-Carrier Molecule

Answer 13

A molecule that stores energy in “high-energy” chemical bonds and released the energy to drive coupled endothermic reactions. In cells, adenosine triphosphate (ATP) is the most common energy-carrier molecule.

Question 14

Entropy

Answer 14

A measure of the amount of randomness and disorder in a system.

Question 15

Enzyme

Answer 15

A protein catalyst that speeds up the rate of specific biological reactions.

Question 16

Exergonic Reaction

Answer 16

A chemical reaction that liberates energy (either as heat or in the form of increased entropy)

Question 17

First Law of Thermodynamics

Answer 17

The principle of physics that states that within any isolated system, energy can be neither created nor destroyed but can be converted from one form to another.

Question 18

Kinetic Energy

Answer 18

The energy of movement; includes light, heat, mechanical movement, and electricity.

Question 19

Metabolic Pathway

Answer 19

A sequence of chemical reactions within a cell, in which the products of one reaction are the reactants for the next reaction.

Question 20

Metabolism

Answer 20

The sum of all chemical reactions that occu within a single cell or within all of the cells of a multicellular organism.

Question 21

Potential Energy

Answer 21

“Stored” energy, normally chemical energy or energy of position within a gravitational field.

Question 22

Product

Answer 22

A atom or molecule that is formed from reactants in a chemical reaction.

Question 23

Reactant

Answer 23

An atom or molecule that is used up in a chemical reaction to form a product.

Question 24

Second Law of Thermodynamics

Answer 24

The principle that any change in an isolated system causes the quantity of concentrated, useful energy to decrease and the amount of randomness and disorder (entropy) to increase.

Question 25

Substrate

Answer 25

The atoms or molecules that are the reactants for an enzyme-catalyzed chemical reaction.