Chapter 8

Question 1

Metabolic pathway

Answer 1

begins with a specific molecule and ends with a product. Each is catalyzed by a specific enzyme

Question 2

Catabolic pathways

Answer 2

release energy by breaking down complex molecules into simpler compounds

Question 3

Anabolic pathways

Answer 3

consume energy to build complex molecules from simpler ones

Question 4

Bioenergetics

Answer 4

the study of how energy flows through living organisms

Question 5

Energy

Answer 5

the capacity to cause change

Question 6

Kinetic energy

Answer 6

energy associated with motion

Question 7

Thermal energy

Answer 7

The Kinetic energy associated with the random movement of molecules or atoms

Question 8

Heat

Answer 8

thermal energy in transfer between objects

Question 9

Potential energy

Answer 9

The energy matter possesses because of its location or structure

Question 10

Chemical energy

Answer 10

potential energy available for release in a chemical reaction

Question 11

Thermodynamics

Answer 11

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

Question 12

First Law of Thermodynamics

Answer 12

Energy can be transferred or transformed, but it cannot be created or destroyed

Question 13

Second Law of Thermodynamics

Answer 13

Every energy transfer or transformation increases the entropy of the universe

Question 14

entropy

Answer 14

a measure of molecular disorder, or randomness

Question 15

Free Energy (ΔG)

Answer 15

the portion of a system’s energy that can perform work when temperature and. pressure are uniform throughout the system

Question 16

Spontaneous processes

Answer 16

occur without energy input; they can happen quickly or slowly

Question 17

ΔG=

Answer 17

ΔG= ΔH-TΔS
ΔH=change in total energy
ΔS=change in entropy
T=temperature in Kelvin

Question 18

ΔG is negative

Answer 18

spontaneous process

Question 19

ΔG is zero or positive

Answer 19

never spontaneous

Question 20

The more free energy

Answer 20

the less stable a system is

Question 21

exergonic reaction

Answer 21

proceeds with a net release of free energy and is spontaneous

Question 22

endergonic reaction

Answer 22

absorbs free energy from its surroundings and is nonspontaneous

Question 23

Reactions in a closed system…

Answer 23

eventually reach an equilibrium and can no longer do work

Question 24

Open system

Answer 24

a material system in which mass or energy can be lost to or gained from the environment

Question 25

Closed system

Answer 25

a natural physical system that does not allow transfer of matter in or out of the system

Question 26

energy coupling

Answer 26

the use of an exergonic processto drive an endergonic one

Question 27

ATP

Answer 27

Adenosine Triphosphate; the cell's energy shuttle

Question 28

ATP is composed of...

Answer 28

ribose (a sugar), adenine(a nitrogenous base), and three phosphate groups

Question 29

_______ brakes the bond between ATP phosphate groups

Answer 29

Hydrolysis

Question 30

Energy is released from ATP when...

Answer 30

the terminal phosphate bond is broken (This release of energy comes from the chemical change to a state of lower free energy, not from the phosphate bonds themselves)

Question 31

phosphorylated intermediate

Answer 31

ATP drives endergonic reactions by phosphorylation, transferring a phosphate group to some other molecule, such as a reactant The recipient molecule is now called a phosphorylated intermediate

Question 32

ATP is a renewable resource that is regenerated...

Answer 32

by addition of a phosphate group to adenosine diphosphate (ADP)

Question 33

Enzymes

Answer 33

A catalytic protein, most which are specific to a certain reaction. Only a small amount are needed because they can be repeatedly used

Question 34

Activation Energy (E subscript A)

Answer 34

or free energy of activation; the initial energy required to start a reaction (often supplied by thermal energy)

Question 35

Catalysis

Answer 35

enzymes or other catalysts speed up specific reactions by lowering the activation energy barrier

Question 36

Substrate

Answer 36

The reactant that an enzyme acts on

Question 37

Enzyme-substate complex

Answer 37

what is formed when an enzyme binds to its substrate

Question 38

Active site

Answer 38

the region on the enzyme where the substrate binds

Question 39

catalytic cycle

Answer 39

Question 40

The active site can lower an EA barrier by...

Answer 40

-orienting substrates correctly -straining substrate bonds -providing a favorable microenvironment -covalently bonding to the substrate

Question 41

The rate of an enzyme-catalyzed reaction can be sped up by...

Answer 41

increasing substrate concentration

Question 42

saturated enzyme

Answer 42

when all enzyme molecules have their active sites engaged

Question 43

Enzymes have optimal ______ and ______ they can operate in

Answer 43

temperature; pH

Question 44

Cofactors

Answer 44

nonprotein enzyme helpers (may be inorganic [such as a metal in ionic form)] or organic [small molecules])

Question 45

Enzyme inhibitors

Answer 45

Things that inhibit enzymes from functioning

Question 46

Coenzyme

Answer 46

An organic cofactor

Question 47

Competitive Inhibitors

Answer 47

bind to the active site of an enzyme, competing with the substrate

Question 48

Noncompetitive inhibitors

Answer 48

bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective

Question 49

Allosteric regulation

Answer 49

the term used to describe any case in which a protein's function at one site is affected by the binding of a regulatory molecule to a separate sight

Question 50

cooperativity

Answer 50

amplifies the response of enzymes to substrates

Question 51

Feedback inhibition

Answer 51

when a metabolic pathway is halted by the inhibitory binding off its end product to an enzyme that acts early in the pathway