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Biology 111 > chapter 8: energy and enzymes > Flashcards

chapter 8: energy and enzymes Flashcards

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
why are catabolic reactions exergonic?
bc it is going from going from high pe (order) to low pe (disorder) .... increasing entropy
26
anabolic reactions
produce a single product (highly ordered substance) out of many smaller reactants (less ordered) positive ΔG
27
anabolic reactions are...
endergonic (nonspontaneous)
28
why are anabolic reactions endergonic?
bc its building from low pe (disorder) to high pe (order)
29
temperature and concentration affect what?
reactions
30
for most reactions to continue what two things must happen?
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
31
what increases # of collisions and reaction rate?
1. higher concentration of reactants 2. higher temp.
32
reactants can also be called what
substrates / molecules
33
energetic coupling allows for endergonic reactions to proceed using what?
free energy from exergonic reactions
34
energetic couplins between exergonic and endergonic reactions transfers...
free energy from one reaction to drive another reaction
35
energetic couple in a cell occurs 1 of 2 ways...
1. through transfer of electrons 2. through transfer of phosphate group
36
reduction-oxidation reactions / redox reactions
chemical reactions that involve loss/gain of electrons
37
oxidation
loss of an electron/s (exergonic half)
38
reduction
gain of an electron/s (endergonic half)
39
T/F: oxidation reactions are always paired w. reduction reactions
true! you dont get oxidation without reduction (vice versa) if one atom/molecule loses an electron, another has to gain it
40
what do redox/ reduction-oxidation reactions represent?
energetic coupling of two half reactions
41
does oxidation lower pe or raise pe of reactant ?
lowers pe making it spontaneous (exergonic half)
42
does reduction lower or raise pe of reactant?
raises pe making it non-spontaneous (endergonic half)
43
what can be gained or loss during formation of new chemical bonds?
electrons
44
ATP hydrolysis releases...
free energy
45
ATP has great deal of what?
potential energy
46
why does ATP have great deal of PE
due to the repulsive forces of 3 negatively charged phosphate groups (neg on neg)
47
During ATP hydrolysis what is broken?
bond between ATP outermost phosphate group and its neighbor
48
what does this broken bond between ATP outermost phosphate group and its neighor result in?
production of ADP and inorganic phosphate anddd release of free energy
49
ADP
adenosine diphosphate
50
inorganic phosphate
Pi/HPO4-
51
what does the free energy from ATP hydrolysis fuel?
Endergonic reactions
52
do cells lose the energy produced by ATP Hydrolysis as heat?
no
53
what do the cells use the energy for (produced by atp hydrolysis as heat)???
use it for other cellular reactions
54
ATP hydroylsis is couples with...
endergonic reactions
55
energy produced by ATP hydroylsis is used in...
phosphorylation reaction
56
phosphorylation reaction
addition of a phosphate group to target molecule (added to a protein)
57
when a phosphate group from ATP is added to one of the reactant molecules, this new bond formed with the phosphate increases...
potential energy of reactant
58
what is the phosphorylated intermediated referred to as ?
being activated
59
all reactions cross / overcome what?
an energy barrier
60
this energy barrier allows for the reaction to...
proceed/continue
61
what state does the energy barrier get reactants to?
transition state
62
transition state
bonds of reactants become twisted/bent (high energy, unstable state of reactants)
63
activation energy
initial investment of energy needed to bend/twist reactant molecules so their bonds can break down
64
do enzymes lower or raise activation energy of chemical reactions?
lower
65
enzymes act as...
catalysts and assist with clearing 2 hurdles of chemical reaction
66
2 hurdles of chemical reactions that enzymes help with...
1. bring reactants tg. in precise orientation making reaction more likely to occur 2. lower activation energy of reaction
67
enzyme function is assisted by additional molecules (3)
1. cofactors 2. coenzymes 3. prosthetic groups
68
cofactors
inorganic ions (Mg 2+) that reversibly interact w. enzymes
69
coenzymes
organic molecules that reversibly interact with enzymes (NAD+)
70
prosthetic groups
inorganic or organic molecules that irreversibly interact w. enzymes (heme group)
71
binding to active site of enzyme helps substrates...
come tg. in precise orientation and adds strain to the bonds that leads to transition state making reactants unstable
72
what do the active site of enzymes promote?
transition state of reactants which lowers the reactions activation energy
73
do enzymes change ΔG of a reaction?
NOOOOO
74
can enzymes become saturated?
yes they can
75
ΔG
change in free energy
76
ΔH
change in enthalpy
77
ΔS
change in entropy
78
reactions increase in a steep fashion ifffff
the amount of substrate/reactants is less than amount of enzyme
79
at intermediate levels of substrate reactions...
begin to slow
80
equal or higher concentration of substrates than enzyme (concent.)
the reaction plateaus
81
all enzymes show type of
saturation kinetics
82
all available enzymes molecules being used (saturated) make reaction rates
level off
83
all enzymes and their active sites become filled so they can no longer what?
accept substrates no matter how big the concentration of substrates gets
84
enzymatic activity is affect by...
temp and pH
85
temperature affects folding and movement of what?
enzymes and substrates
86
pH affects enzymes...
shape and reactivity
87
how does pH affect enzymes shape and reactivity?
by affecting the charge on acidic and basic residue
88
enzymes are highly
regulated
89
what 2 ways are enzymes highly regulated NON covalently
1. competitive inhibition 2. allosteric regulation (non-competitive inhibition)
90
competitive inhibition
regulatory molecule binds to active site of enzymes and competes with substrate (also binds to active site)
91
allosteric regulation (non competitive inhibition)
regulatory molecule interacts with the enzyme on-site distinct from the active site, resulting in conformation change that obscures the active site
92
Enzymes are regulated covalently in 1 way
phosphorylation
93
(phosphorylation) the addition of a negatively charged phosphate/phosphoryl group to an amino acid can result in
conformation change in overall protein structure which may activate or inactivate active site!
94
enzymes work together during...
metabolic reactions
95
metabolic pathway is when
many enzymes work tg to produce finalized end product
96
1st reaction of metabolic pathway starts with...
enzyme 1 converting substrate 1 into an intermediate product A
97
intermediate product A acts as a
substrate for enzyme 2 which converts it to intermediate B
98
1 way metabolic reactions regulate level of products in a pathway is by
using end product to inhibit an enzyme of the pathway (feedback inhibition)

Biology 111 (10 decks)

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