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BIOLOGY 204 > UNIT 4 ENERGY AND ENZYMES > Flashcards

UNIT 4 ENERGY AND ENZYMES Flashcards

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1
Q

Central role of energy

A

Is the ability to do work.

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2
Q

Types of energy.

A

Heat, chemical, electrical, mechanical, electromagnetic radiation.

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3
Q

Forms of energy

A

Kinetic and potential

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4
Q

What is the first law of thermodynamics?

A

Energy can be transferred from one form to another but can’t be destroyed or created.

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5
Q

What is the second law of thermodynamics?

A

Every time the energy is transferred, some energy is lost and unavailable to do work. This lost energy creates entropy.

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6
Q

Does spontaneous reactions require the input of energy?

A

No

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7
Q

The change in free energy must be negative for the reaction to be spontaneous?

A

Yes

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8
Q

What is kinetic energy?

A

Energy possessed by an object in motion.

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9
Q

What is potential energy?

A

The stored energy that an object has because of it’s location or chemical structure.

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10
Q

The study of energy and it’s transformation is called?

A

Thermodynamics

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11
Q

What are the 3 systems studied in thermodynamics?

A

Isolated, open, closed

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12
Q

What is an isolated system?

A

One that doesn’t exchange matter or energy with it’s surroundings. (thermos)

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13
Q

What is an open system?

A

One that the matter and energy can move freely between the system and it’s surroundings. (living organisms)

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14
Q

What is a closed system?

A

Exchange energy but not matter with it’s surrounding.(earth)

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15
Q

The unusable energy that is produced during energy transformation produces what?

A

An increase in the disorder of the universe. (entropy)

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16
Q

The entropy of a system and it’s surroundings always increases?

A

yep

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17
Q

What does it take to maintain low entropy?

A

Energy

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18
Q

What do we do to maintain low entropy?

A

We eat food, aka we bring in energy.

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19
Q

Reactions tend to be spontaneous when?

A

The products have less potential energy than the reactants.

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20
Q

Enthalphy?

A

potential energy in a system

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21
Q

endothermic

A

reactions that absorbs energy. products have more potential energy than reactants.

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22
Q

exothermic

A

reaction that releases energy. Products have less potential energy than reactants.

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23
Q

Free energy

A

energy available to do work. Abbreviated by G.

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24
Q

Free energy formula?

A

G= H - TxS
H change in enthalpy
S change in entropy

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25
Q

G must be negative for a spontaneous reaction to occur?

A

yep

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26
Q

Systems that have high free energy are more or less stable?

A

Less stable

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27
Q

Can systems change into being less stable?

A

No, but they can change to being more stable.

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28
Q

What is equilibrium?

A

A state in which the reaction doesn’t stop and the rate of the forward reaction equals the rate of the backward reaction.

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29
Q

Closer to the equilibrium means?

A

Less free energy.

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30
Q

The more negative free energy = what for equilibrium?

A

The further the reaction will more before equilibrium is established.

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31
Q

When does organisms reach equilibrium?

A

Only when they die.

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32
Q

Metabolic pathway

A

series of reactions where the products of one reaction. is immediately used as the reactant for the next reaction in the series.

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33
Q

Metabolic pathway consists of ?

A

Exergonic and endergonic reactions

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34
Q

Catabolic pathway

A

Energy is released by the breakdown of complex molecules to simpler compounds.

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35
Q

Anabolic pathway

A

Consumes energy to build complex molecules from simpler ones.

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36
Q

Energy currency of cells

A

ATP

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37
Q

What is hydrolysis?

A

A process in which free energy is released.

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38
Q

How does hydrolysis works?

A

Each phosphate group are close together but their negative charges makes them repel each other, making the bonds unstable.The removal of one or two group Is spontaneous reaction that releases the repulsion and releases free energy.

39
Q

ATP to ADP releases more energy than?

A

ATP to AMP

40
Q

How does a living cell doesn’t loose energy as heat by hydrolysis?

A

By energy coupling.

41
Q

How does energy coupling works?

A

ATP is brought close to a reactant of an endergonic reaction. When the ATP is hydrolyzed, the terminal phosphate group is transferred to the reactant molecule This makes the reactant molecule less stable

42
Q

What brings the ATP and reactant close together in energy coupling?

A

Enzyme

43
Q

Energy coupling produces an overall reaction that is?

A

exergonic

44
Q

The energy for ATP synthesis comes from?

A

from an exergonic breakdown of complex molecules that contains a lot of free energy. Ex food

45
Q

How can the speed of a reaction be changed?

A

by enzymes

46
Q

What needs to be done for a reaction to happen quickly?

A

The bonds must be broken and to do so, they need to be less stable (input of energy).

47
Q

Activation energy

A

to get molecules into an unstable state (to break them) it need a little input of energy.

48
Q

Transition state

A

molecules that gain activation energy and that the bonds are now ready to break.

49
Q

activation energy prevents what?

A

spontaneous reactions to happen quickly

50
Q

How does enzymes accelerate reactions?

A

by reducing the activation energy

51
Q

catalyst

A

agent that speeds up the rate of reacti0on without taking part of it itself.

52
Q

Most common catalyst?

A

enzyme

53
Q

enzymes do what?

A

reduce the activation energy required for a reaction to occur.

54
Q

enzymes only work on?

A

exergonic reactions as they cant supply free energy

55
Q

does enzymes change the free energy of a reaction?

A

nope

56
Q

enzyme specificity

A

only catalyzes reactions for a single type of protein

57
Q

substrate

A

reactant the enzyme acts with.

58
Q

what is the active site of the enzyme?

A

th4 small region where the subtrate interacts

59
Q

induced-fit hypothesis

A

Just before substrate binding, the enzyme changes its shape so that the active site becomes even more precise in its ability to bind the substrate.

60
Q

enzyme cycle

A

because the enzyme is unchanged after a reaction, it can binds again to a substrate, catalyzing the reaction again.

61
Q

cofactor

A

non-protein group that binds to an enzyme. often metals

62
Q

coenzyme

A

organic cofactors such as vitamins

63
Q

enzymes reduces the activation energy by inducing the transition state by

A
  • bringing reactants together
  • exposing reactants to charged environment
  • changing the substrate shape, which mimics the conformation of the transition state.
64
Q

more enzymes =

A

more reactions

65
Q

more substrate =

A

faster reactions

66
Q

less substrate=

A

slower reactions

67
Q

what does it mean when an enzyme is saturated with substrates?

A

When the substate increases, the rate of reaction also increases until the enzymes are cycling as quickly as possible.

68
Q

enzyme inhibitor

A

molecule that binds to an enzyme and decrease it’s activity.

69
Q

two names of the enzyme inhibitors

A

competitive inhibition and non competitive inhibition

70
Q

What is competitive inhibition?

A

The molecule binds to the active site. it has a shape that ressembles the normal substrate and it blocks its access.

71
Q

What is non-competitive inhibition?

A

The molecule binds to the critical site, elsewhere on the enzyme, it causes the enzyme to change shape so it doesn’t fit with the substrate anymore.

72
Q

Reversible inhibition?

A

When the binding of inhibitors to the enzyme is weak, it is easily reversible and the enzyme activity returns to normal after the release of the inhibitor.

73
Q

Non-reversible inhibition?

A

When inhibitors bind to the enzyme with covalent bon ds which completely disable it.

74
Q

Irreversible inhibition is ?

A

Highly toxic to living cells.

75
Q

What is a futile cycle?

A

When two metabolic process run at the same time in the opposite direction and only has the effect of loosing energy.

76
Q

How do cells prevent futile cycle?

A

The cells control the enzyme activity with natural inhibitors, so that not all enzymes are active at the same time.

77
Q

Allosteric regulation

A

When the enzyme activity is controlled by the reversible binding of a regulatory molecule to the allosteric site. This may increase or decrease the enzyme activity.

78
Q

Where is the allosteric site?

A

Location on the enzyme, outside of the active site

79
Q

Are allosteric inhibitors competitive or non-competitve>

A

Non-competitive because they bind to sites different to the active site.

80
Q

Enzymes controlled by allosteric regulation have two conformations controlled by the allosteric site, what are they?

A
  • High affinity state

- low affinity state

81
Q

What is the high affinity state?

A

When the enzyme is active because it can bind to it’s substrate. (allosteric inhibition)

82
Q

What is the low affinity state?

A

When the enzyme is inactive because it cant bind to it’s substate (allosteric inhibition).

83
Q

What does allosteric inhibitors do?

A

They bind to allosteric enzymes and change their state from high to low.

84
Q

What does binding an allosteric enzyme to an allosteric activator does what?

A

Change the state of the enzyme from low to high.

85
Q

Allosteric inhibitors comes from what?

A

is a product of metabolic pathway that they regulate.

86
Q

What do allosteric inhibitors regulates?

A

If a product is in excess, it will slow or stop the enzymatic reaction producing it. If a product is needed, the inhibition is reduced and the production increases.

87
Q

Regulation when a product of a reaction acts as a regulator of the reaction is called?

A

Feedback inhibition

88
Q

What does feedback inhibition does?

A

Prevents cellular ressources from being wasted in the synthesis of molecules made in intermediate steps.

89
Q

What are some factors affecting enzyme activity?

A

Ph, temperature.

90
Q

If Ph is not optimal =

A

The rate of catalyzed reactions decreases.

91
Q

If temperature rises=

A

The rate of reaction increases and potentially denatures the enzyme.

92
Q

Equilibrium can only happen in what system?

A

Closed system

93
Q

spontaneous reaction

A

reactions that occur without the input of energy.

94
Q

energy coupling

A

use of exergonic process to drive a endergonic process

BIOLOGY 204 (9 decks)

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