Chapter 8 Introduction to metabolism

Question 1

Bioenergetics

Answer 1

(1) The overall flow and trans- formation of energy in an organism. (2) The study of how energy flows through organisms

Question 2

kinetic energy

Answer 2

The energy associated with the relative motion of objects. moving matter can perform work by imparting motion to other matter

Question 3

Thermal energy

Answer 3

Kinetic energy due to the random motion of atoms and molecules; energy in its most random form

Question 4

Heat

Answer 4

Thermal energy in transfer from one body of matter to another

Question 5

Potential energy

Answer 5

The energy that matter possesses as a result of its location or spatial arrangement (structure)

Question 6

Chemical energy

Answer 6

Energy available in molecules for release in a chemical reaction; a form of potential energy

Question 7

Metabolism

Answer 7

The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism

Question 8

Metabolism

Answer 8

The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism

Question 9

Metabolic pathway

Answer 9

A series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule to simpler molecules (catabolic pathway).

Question 10

Catabolic pathway

Answer 10

A metabolic pathway that releases energy by breaking down complex molecules to simpler molecules

Question 11

Anabolic pathway

Answer 11

A metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules

Question 12

Thermodynamics

Answer 12

The study of energy transformations that occur in a collection of matter

Question 13

First law of Thermodynamics

Answer 13

The principle of conservation of energy: Energy can be transferred and transformed, but it cannot be created or destroyed

Question 14

Second law of Thermodynamics

Answer 14

The principle stating that every energy transfer or transformation increases the entropy of the universe. Usable forms of energy are at least partly converted to heat

Question 15

Entropy

Answer 15

A measure of molecular disorder, or randomness

Question 16

Spontaneous process

Answer 16

A process that occurs without an overall input of energy; a process that is energetically favorable

Question 17

Free energy

Answer 17

The portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system. The change in free energy of a system (∆G) is calculated by the equation ∆G = ∆H - T∆S, where ∆H is the change in enthalpy (in biological systems, equivalent to total energy), ∆T is the absolute temperature, and ∆S is the change in entropy

Question 18

Exergonic reaction

Answer 18

A spontaneous chemical reaction in which there is a net release of free energy

Question 19

Endergonic reaction

Answer 19

A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings

Question 20

ATP (adenosine tri-phospahte)

Answer 20

n adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells

Question 21

Phosphorylated intermediate

Answer 21

A molecule (often a reactant) with
a phosphate group covalently bound to it, making it more reactive (less stable) than the unphosphorylated molecule.

Question 22

Enzyme

Answer 22

A macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction. Most enzymes are proteins

Question 23

Catalysis

Answer 23

A process by which a chemical agent called a catalyst selectively increases the rate of a reaction without being consumed by the reaction

Question 24

Energy coupling

Answer 24

In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction

Question 25

Activation energy

Answer 25

Theamountofenergy that reactants must absorb before a chemical reaction will start; also called free energy of activation

Question 26

Catalyst

Answer 26

A chemical agent that selectively increases the rate of a reaction without being consumed by the reaction

Question 27

Substrate

Answer 27

The reactant on which an enzyme works

Question 28

Enzyme-substrate complex

Answer 28

A temporary complex formed when an enzyme binds to its substrate molecule(s)

Question 29

Active site

Answer 29

The specific region of an enzyme that binds the substrate and that forms the pocket in which catalysis occurs

Question 30

Induced fit

Answer 30

Caused by entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate

Question 31

Cofactor

Answer 31

Any nonprotein molecule or ion that is required for the proper functioning of an enzyme. Cofactors can be permanently bound to the active site or may bind loosely and reversibly, along with the substrate, during catalysis

Question 32

Coenzyme

Answer 32

An organic molecule serving as a cofactor. Most vitamins function as coenzymes in metabolic reactions

Question 33

Competitive inhibitors

Answer 33

A substance that reduces the activity of an enzyme by entering the active site in place of the substrate, whose structure it mimics

Question 34

non-competitive inhibitors

Answer 34

A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing the enzyme’s shape so that the active site no longer effectively catalyzes the conversion of substrate to product

Question 35

Allosteric regulation

Answer 35

The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site

Question 36

Cooperativity

Answer 36

A kind of allosteric regulation whereby a shape change in one subunit of a protein caused by substrate binding is transmitted to all the other subunits, facilitating binding of additional substrate molecules to those subunits

Question 37

Feedback inhibition

Answer 37

A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway