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Biology 111 > chapter 8: energy and enzymes > Flashcards

chapter 8: energy and enzymes Flashcards

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1
Q

what do complex chemical reactions sustain life require?

A

energy

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2
Q

energy is the ability to do …

A

work

(dynamic)

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3
Q

1st law of thermodynamics

A

in any system, energy is not consumed but it is rearranged/transformed from 1 form into another

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4
Q

2 forms energy exists

A
  1. potential energy (stored)
  2. kinetic energy (motion)
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5
Q

does enery alternate between pe and ke?

A

yesss

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6
Q

can chemical reactions be spontaneous?

A

yes but does not mean it will happen quickly

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7
Q

how can chemical reactions be spontaneous?

A

if after their intiation they can proceed on their own w/o having to add energy

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8
Q

2 conditions must be met for reactions to be spontaneous

A

products must
1. have lower pe than reactants
2. higher entropy than reactants (more disordered)

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9
Q

is it easier to break things down or build things?

A

break bc it is spontaneous

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10
Q

2nd law of thermodynamic

A

in all spontaneous reactions, entropy always increased and usable energy decreases

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11
Q

theres more disorder if

A

entropy increases

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12
Q

enthalpy

A

total energy of a system

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13
Q

gibbs free energy

A

usuable energy that can do work

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14
Q

entropy

A

unusable energy that is lost to disorder

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15
Q

in any biological system total energy of that system. (enthalpy) =

A

sum of (Gibbs) free energy and entropy

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16
Q

faster molecules move due to incr. temp =

A

more disorder

so Temp is multiplied by change in entropy (delta S)

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17
Q

what is primarily based on differences in potential energy?

A

changed in enthalpy

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18
Q

ΔG = ΔH - TΔS tells us…

A

whether free energy is released or consumed by chemical reactions

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19
Q

if ΔG is negative free energy is…

A

released therefore chemical reactions are spontaneous

exergonic

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20
Q

if ΔG is positive (greater than 0), free energy is …

A

required (consumed) therefore non spontaneous

endergonic

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21
Q

if ΔG is 0, what is reached?

A

equilibrium

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22
Q

what directions do spontaneous chemical reactions proceed in?

A

direction that lowers free energy of the system

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23
Q

catabolic reactions

A

break down an ordered reactant into smaller, more randomly distributed products

negative ΔG

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24
Q

catabolic reactions are…

A

exergonic (spontaneous)

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25
Q

why are catabolic reactions exergonic?

A

bc it is going from going from high pe (order) to low pe (disorder) …. increasing entropy

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26
Q

anabolic reactions

A

produce a single product (highly ordered substance) out of many smaller reactants (less ordered)

positive ΔG

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27
Q

anabolic reactions are…

A

endergonic (nonspontaneous)

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28
Q

why are anabolic reactions endergonic?

A

bc its building from low pe (disorder) to high pe (order)

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29
Q

temperature and concentration affect what?

A

reactions

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30
Q

for most reactions to continue what two things must happen?

A
  1. 1 or more chemical bonds must break and one or more new bonds must form
  2. substances must collide in specific orientation to bring electrons involved near eachother other
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31
Q

what increases # of collisions and reaction rate?

A
  1. higher concentration of reactants
  2. higher temp.
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32
Q

reactants can also be called what

A

substrates / molecules

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33
Q

energetic coupling allows for endergonic reactions to proceed using what?

A

free energy from exergonic reactions

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34
Q

energetic couplins between exergonic and endergonic reactions transfers…

A

free energy from one reaction to drive another reaction

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35
Q

energetic couple in a cell occurs 1 of 2 ways…

A
  1. through transfer of electrons
  2. through transfer of phosphate group
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36
Q

reduction-oxidation reactions / redox reactions

A

chemical reactions that involve loss/gain of electrons

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37
Q

oxidation

A

loss of an electron/s (exergonic half)

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38
Q

reduction

A

gain of an electron/s (endergonic half)

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39
Q

T/F: oxidation reactions are always paired w. reduction reactions

A

true!

you dont get oxidation without reduction (vice versa)

if one atom/molecule loses an electron, another has to gain it

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40
Q

what do redox/ reduction-oxidation reactions represent?

A

energetic coupling of two half reactions

41
Q

does oxidation lower pe or raise pe of reactant ?

A

lowers pe making it spontaneous

(exergonic half)

42
Q

does reduction lower or raise pe of reactant?

A

raises pe making it non-spontaneous

(endergonic half)

43
Q

what can be gained or loss during formation of new chemical bonds?

A

electrons

44
Q

ATP hydrolysis releases…

A

free energy

45
Q

ATP has great deal of what?

A

potential energy

46
Q

why does ATP have great deal of PE

A

due to the repulsive forces of 3 negatively charged phosphate groups
(neg on neg)

47
Q

During ATP hydrolysis what is broken?

A

bond between ATP outermost phosphate group and its neighbor

48
Q

what does this broken bond between ATP outermost phosphate group and its neighor result in?

A

production of ADP and inorganic phosphate anddd release of free energy

49
Q

ADP

A

adenosine diphosphate

50
Q

inorganic phosphate

A

Pi/HPO4-

51
Q

what does the free energy from ATP hydrolysis fuel?

A

Endergonic reactions

52
Q

do cells lose the energy produced by ATP Hydrolysis as heat?

A

no

53
Q

what do the cells use the energy for (produced by atp hydrolysis as heat)???

A

use it for other cellular reactions

54
Q

ATP hydroylsis is couples with…

A

endergonic reactions

55
Q

energy produced by ATP hydroylsis is used in…

A

phosphorylation reaction

56
Q

phosphorylation reaction

A

addition of a phosphate group to target molecule

(added to a protein)

57
Q

when a phosphate group from ATP is added to one of the reactant molecules, this new bond formed with the phosphate increases…

A

potential energy of reactant

58
Q

what is the phosphorylated intermediated referred to as ?

A

being activated

59
Q

all reactions cross / overcome what?

A

an energy barrier

60
Q

this energy barrier allows for the reaction to…

A

proceed/continue

61
Q

what state does the energy barrier get reactants to?

A

transition state

62
Q

transition state

A

bonds of reactants become twisted/bent (high energy, unstable state of reactants)

63
Q

activation energy

A

initial investment of energy needed to bend/twist reactant molecules so their bonds can break down

64
Q

do enzymes lower or raise activation energy of chemical reactions?

A

lower

65
Q

enzymes act as…

A

catalysts and assist with clearing 2 hurdles of chemical reaction

66
Q

2 hurdles of chemical reactions that enzymes help with…

A
  1. bring reactants tg. in precise orientation making reaction more likely to occur
  2. lower activation energy of reaction
67
Q

enzyme function is assisted by additional molecules (3)

A
  1. cofactors
  2. coenzymes
  3. prosthetic groups
68
Q

cofactors

A

inorganic ions (Mg 2+) that reversibly interact w. enzymes

69
Q

coenzymes

A

organic molecules that reversibly interact with enzymes (NAD+)

70
Q

prosthetic groups

A

inorganic or organic molecules that irreversibly interact w. enzymes (heme group)

71
Q

binding to active site of enzyme helps substrates…

A

come tg. in precise orientation and adds strain to the bonds that leads to transition state making reactants unstable

72
Q

what do the active site of enzymes promote?

A

transition state of reactants which lowers the reactions activation energy

73
Q

do enzymes change ΔG of a reaction?

A

NOOOOO

74
Q

can enzymes become saturated?

A

yes they can

75
Q

ΔG

A

change in free energy

76
Q

ΔH

A

change in enthalpy

77
Q

ΔS

A

change in entropy

78
Q

reactions increase in a steep fashion ifffff

A

the amount of substrate/reactants is less than amount of enzyme

79
Q

at intermediate levels of substrate reactions…

A

begin to slow

80
Q

equal or higher concentration of substrates than enzyme (concent.)

A

the reaction plateaus

81
Q

all enzymes show type of

A

saturation kinetics

82
Q

all available enzymes molecules being used (saturated) make reaction rates

A

level off

83
Q

all enzymes and their active sites become filled so they can no longer what?

A

accept substrates no matter how big the concentration of substrates gets

84
Q

enzymatic activity is affect by…

A

temp and pH

85
Q

temperature affects folding and movement of what?

A

enzymes and substrates

86
Q

pH affects enzymes…

A

shape and reactivity

87
Q

how does pH affect enzymes shape and reactivity?

A

by affecting the charge on acidic and basic residue

88
Q

enzymes are highly

A

regulated

89
Q

what 2 ways are enzymes highly regulated NON covalently

A
  1. competitive inhibition
  2. allosteric regulation (non-competitive inhibition)
90
Q

competitive inhibition

A

regulatory molecule binds to active site of enzymes and competes with substrate (also binds to active site)

91
Q

allosteric regulation (non competitive inhibition)

A

regulatory molecule interacts with the enzyme on-site distinct from the active site, resulting in conformation change that obscures the active site

92
Q

Enzymes are regulated covalently in 1 way

A

phosphorylation

93
Q

(phosphorylation) the
addition of a negatively charged phosphate/phosphoryl group to an amino acid can result in

A

conformation change in overall protein structure which may activate or inactivate active site!

94
Q

enzymes work together during…

A

metabolic reactions

95
Q

metabolic pathway is when

A

many enzymes work tg to produce finalized end product

96
Q

1st reaction of metabolic pathway starts with…

A

enzyme 1 converting substrate 1 into an intermediate product A

97
Q

intermediate product A acts as a

A

substrate for enzyme 2 which converts it to intermediate B

98
Q

1 way metabolic reactions regulate level of products in a pathway is by

A

using end product to inhibit an enzyme of the pathway (feedback inhibition)

Biology 111 (10 decks)

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