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BIOL2520 > Unit 03: Bioenergetics, Enzymes and Metabolism > Flashcards

Unit 03: Bioenergetics, Enzymes and Metabolism Flashcards

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1
Q

define metabolism

A

all of the chemical processes that a cell carries out to survive, grow and reproduce

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2
Q

define catabolism

A

breakdown of complex molecules into smaller subunits, generating energy.

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3
Q

define anabolism

A

building of large, complex molecules from smaller subunits that consume energy

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4
Q

what is another term for anabolism?

A

biosynthesis

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5
Q

the larger a molecules, the more ____ it is.

A

ordered

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6
Q

t/f; cells are little islands of disorder in an extremely ordered environment

A

false!

cells are islands of order in an extremely disordered environment

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7
Q

what is the second law of thermodynamics?

A

the total entropy of a system (namely the universe) is always increasing

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8
Q

what is the most disordered form of energy?

A

heat

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9
Q

what happens in terms of entropy when a cell releases heat?

A

the entropy of the cell decreases while the entropy of its external environment increases

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10
Q

what is the first law of thermodynamics?

A

energy cannot be created or destroyed, but converted from one form to another

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11
Q

what is gained/lost in oxidation?

A

lose hydrogen, gain oxygen

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12
Q

what is gained/lost in reduction?

A

gain hydrogen, lose oxygen

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13
Q

what occurs in dehydrogenation reactions

A

since we are losing hydrogens, oxidation occurs

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14
Q

what occurs in hydrogenation reactions

A

since we are gaining hydrogens, reduction occurs

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15
Q

what is the most reduced form of formaldehyde?

A

methane

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16
Q

what is the most oxidized form of formaldehyde?

A

carbon dioxide

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17
Q

what do changes in free energy reflect?

A

how much disorder is generated in the universe by a reaction

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18
Q

are reactions with less disorder more/less favourable?

A

less

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19
Q

how do enzymes use free energy?

A

harness free energy to drive energetically unfavourable rxns to produce order

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20
Q

describe the spontaneous direction for a reaction.

A

the “downhill” reaction that is energetically favourable

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21
Q

in an activation energy curve for a spontaneous reaction, the reactants are at ____ order and then pushed to a ______ level of order to reach the activation energy, after which the products reach a ______ level of order

A

intermediate, high, low

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22
Q

how do enzymes influence the rate of a rxn?

A

increase it by increasing the collision of molecules, since it is trying to bind to them and see what sticks

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23
Q

how much faster can enzymes make a rxn?

A

up to 10^14 times faster

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24
Q

are enzymes very broad in terms of which substrates they can bind to?

A

no they are very specific! each enzyme can only bind to a specific substrate (lock and key)

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25
what are the common characteristics of energetically favourable reactions?
- positive/high entropy - negative delta G - spontaneous - catabolism
26
what are the common characteristics of energetically unfavourable reactions?
- negative/low entropy - positive delta G - non spontaneous - anabolism
27
what happens to the delta G value as the reaction reaches equilibrium ?
decreases until it reaches 0
28
do cells want to be in equilibrium? why or why not?
no! bc if at equlibrium, no chemical processes are taking place which is bad for the cell.
29
what happens when the equilibrium value of a reaction (K) is greater than 1
more products are produced
30
what happens when the equilibrium value of a reaction (K) is less than 1
more substrates are produced
31
in a reaction where 2 reactants combine to make one product, what does it rely on to create the bond?
rate of collision proportional to proportional to concentration of reactants
32
why is cellular respiration as a whole energetically favourable when so many of the reactions involved are unfavourable?
because the free energy changes of the reactions within cellular respiration are additive, and add up to a very negative delta G making the whole process very energetically favourable
33
what is the delta G value for cellular respiration?
-2880 kJ/mol
34
describe how an unfavourable reaction can be driven by a favourable reaction?
by using an enzyme supplemented by another enzyme harnessing the free energy released by a favourable reaction to power it
35
do substrates typically find enzymes? why or why not?
yes because they are much smaller than the enzymes so are able to weave around
36
how long does it take a small substrate to diffuse 10μm?
1/5 of a second
37
what kind of interactions bind enzyme and substrate?
weak interactions (h- bonding, ionic bonds, van der waals forces)
38
describe how enzyme and substrate will bind despite random thermal motion?
if the free energy of the complex is lower than the sum of the free energies of them separately
39
why do phosphoanhydride bonds have so much stored energy?
because phosphates are all very negative, therefore they do not want to be close together. so, it takes lots of energy to keep them close together which is stored in their bonds.
40
what are activated carriers? give a few common examples.
small organic molecules that contain one or more energy rich covalent bonds. ex. ATP, NADH, NADPH
41
what does an enzyme do with the energy released during an oxidation reaction?
makes sure that it is captured in an energy useful form
42
since ATP involves the formation of phosphoanhydride bonds, we know that the process is energetically ____
unfavourable
43
the hydrolysis of ATP is energetically _____
favourable
44
as electrons move down the ETC, do they lose or gain energy?
lose
45
what is the purpose of NADH and NADPH?
carry and pass along high energy electrons and hydrogens
46
is NADH involved in anabolic or catabolic rxns?
catabolic
47
is there low or high concentration of NADH inside the cell compared to NAD+?
low
48
is NADPH involved in anabolic or catabolic rxns?
anabolic
49
is there low or high concentration of NADPH inside the cell compared to NADP+?
high
50
is NADPH a reducing or oxidizing agent?
oxidizing
51
is NADH a reducing or oxidizing agent?
oxidizing
52
many carriers have _____ as a part of their structure
nucleotides
53
what is considered a relic from the early days of cellular evolution where RNA molecules acted like enzymes?
the presence of the nucleotide structure in carriers
54
what are ribozymes?
when RNA acts as an enzyme
55
what group is in ATPs high energy linkage?
phosphate
56
what group is in NADH, NADPH, FADH2 high energy linkage?
electrons and hydrogens
57
what group is in Acetyl-CoA high energy linkage?
acetyl group
58
what group is in carboxylated biotins high energy linkage?
carboxyl group
59
what group is in S-Adenosylmethionine high energy linkage?
methyl group
60
what group is in uridine diphosphate glucose high energy linkage?
glucose
61
what do condensation reactions depend on?
energy provided by hydrolysis of nucleotide triphosphate
62
what is the typical delta G for the ATP hydrolysis to ADP and an inorganic phosphate?
-46 to -54 kJ/mol
63
why is ATP hydrolysis altered to produce AMP and 2 phosphates?
produce more free energy!
64
describe the steps of ATP hydrolysis to produce AMP and 2 phosphates.
1. pyrophosphate group breaks away from ATP producing AMP 2. pyrophosphate breaks into 2 seperate phosphate groups
65
what is the average delta G for the hydrolysis of ATP to AMP and 2 phosphates
-109 kJ/mol

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