Chapter 8 Flashcards

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1
Q

metabolic pathway

A

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

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2
Q

catabolic pathway

A

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

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3
Q

anabolic pathway

A

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

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4
Q

bioenergetics

A

the study of how energy flows through living organisms

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5
Q

thermodynamics

A

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

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6
Q

first law of thermodynamics

A

energy of the universe is constant; it can be transferred and transformed, but it cannot be created or destroyed

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7
Q

entropy

A

a measure of molecular disorder or randomness

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8
Q

second law of thermodynamics

A

every energy transfer or transformation increases the entropy of the universe

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9
Q

spontaneous process

A

a process that leads to an increase in entropy and can proceed without requiring an input of energy

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10
Q

free energy

A

the portion of a system’s energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell

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11
Q

change in free energy equation

A

deltaG=deltaH-TdeltaS
change in free energy=change in enthalpy - temperature x change in entropy

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12
Q

exergonic reaction

A

net release of free energy

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13
Q

endergonic reaction

A

absorbs free energy from its surroundings

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14
Q

energy coupling

A

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

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15
Q

ATP

A

contains the sugar ribose, with the nitrogenous base adenine and a chain of three phosphate groups (the triphosphate group) bonded to it

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16
Q

phosphorylated intermediate

A

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

17
Q

enzyme

A

macromolecule that acts as a catalyst, a chemical agent that speeds up a reaction without being consumed by the reaction; cannot turn a reaction from exergonic to endergonic and vise versa

18
Q

activation energy

A

the energy required to contort the reactant molecules so the bonds can break; the amount of energy needed to push the reactants to the top of an energy barrier

19
Q

catalysis

A

the process where a catalyst selectively speeds up a reaction without being consumed

20
Q

substrate

A

a reactant an enzyme acts on

21
Q

enzyme substrate complex

A

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

22
Q

active site

A

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

23
Q

induced fit

A

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

24
Q

cofactor

A

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

25
Q

coenzyme

A

an organic molecule serving as a cofactor. most vitamins function as coenzymes in metabolic reactions

26
Q

competitive inhibitors

A

reduce the productivity of enzymes by blocking substrates from entering active sites

27
Q

noncompetitive inhibitors

A

do not directly compete with the substrate to bind to the enzyme at the active site. instead, they impede enzymatic reactions by binding to another part of the enzyme. this interaction causes the enzyme molecule to change its shape in such a way that the active site becomes much less effective at catalyzing the conversion of substrate to product

28
Q

allosteric regulation

A

any case in which a protein’s function at one site is affected by the binding of a regulatory molecule to a separate site. it may result in either inhibition or stimulation of an enzyme’s activity

29
Q

cooperativity

A

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

30
Q

feedback inhibition

A

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