Week 6 Flashcards

1
Q

Enthalpy

A

the total energy in a system

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2
Q

Entropy

A

the tendency for ordered things to become random

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3
Q

Free Energy (G)

A

refers to the amount of energy that is available in a system to use

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4
Q

If Product (P) has less free energy than the starting reagents (A and B), the ∆G for this reaction is –

A

Exergonic which means energy (or heat) is released and the reaction will go forward spontaneous

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5
Q

If P has more free energy than A and B, the ∆G is +

A

endergonic (which means energy need to be added for reaction to occur) and the reaction will not spontaneous occur

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6
Q

∆G predicts the…

A

direction of the reaction but doesn’t affect the rate at which the reaction occurs.

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7
Q

Transition state

A

when the substrate is mid-way through the transition to product

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8
Q

when do molecules have the highest potential energy

A

When in transition state/point

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9
Q

Rate of reaction dependent on….

A

activation energy. The smaller the activation energy the quicker the reaction will occur

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10
Q

Function of enzymes

A

speed chemical reactions by lowering the activation energy

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11
Q

what molecule drives endergonic reactions?

A

ATP

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12
Q

energetically favorable reactions

A

the free energy of the reactants is grater than the free energy of the of the product. Therefore, G is negative and the reaction con occur spontaneously

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13
Q

energetically unfavorable reactions

A

G would be positive if the reaction occurred and the universe would become more ordered. So the reaction can only occur if coupled to a second energetically favorable reaction

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14
Q

Active site

A

Site where chemical reaction takes place

Contains functional groups that are actively involved in the reaction

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15
Q

Stabilization of an enzyme

A

Additional bonds form with the enzyme to stabilize the substrate in its transition state. This is how enzymes lower the activation energy.

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16
Q

Substrate binding involves…

A

formation of non covalent bonds and interactions with amino acids from enzymes or cofactors (hydrophobic, electrostatic, and Hbonds)

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17
Q

Enzyme-substrate specificity

A

extremely high specificity due to the chemical shapes/interactions within the substrate binding site

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18
Q

lock and key mechanism

A

substrate binding site creates a 3-D shape that is complementary to the substrate
Enzyme AAs, cofactors, etc interact with substrate via non-covalent interactions

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19
Q

induced fit mechanism

A

Substrate binding to the enzyme induces a conformational change. Helps to reposition functional groups to promote reaction

20
Q

Activation energy

A

energy required to raise substrate energy to the transition state

21
Q

Coenzymes

A

non-protein organic molecules (vitamins).

22
Q

Activation transfer coenzymes

A

Form covalent bond with substrate then activate it for transfer

23
Q

Oxidation reduction coenzymes

A

similar to activation-transfer, but no covalent bond is formed. Functional groups accept or donate electrons

24
Q

metal ions

A

electrophiles. involved in substrate binding, stabilizing anions, donate/accept electrons in redox reactions

25
inhibitors
compounds that decrease the rate of an enzymatic reaction
26
Covalent inhibitors
form covalent bond with functional groups in the active site
27
transition state analogs inhibitors
Bind more tightly to enzyme than substrate to products
28
the velocity of all reaction is dependent on what?
Substrate concentration
29
substrate saturation are found in which reactions?
enzymes catalyzed reactions
30
Michaelis-Menten Equation
E+S ES E+P | Assumes enzyme will let go once the product its formed and will go on to grab more substrate
31
Rate of product formation
is dependent on 2 constants (Km and Vmax) and on the amount of substrate available at that time point
32
Km
1/2 Vmax. allows us to compare affinities
33
Km values for enzymes
are typically just above [S] in the cell, so that the enzyme rate is sensitive to small changes in [S]
34
Catalytic constant/ Turnover number
Kcat = Vmax / [E]total | measured in units per sec
35
irreversible inhibitors
decreases amount of enzyme available
36
Reversible inhibitors
can diffuse away at a significant rate. | Competitive, non competitive, uncompetitive
37
Competitive inhibitors
inhibitor binds to substrate-binding site. | Km is increased. Vmax is the same
38
non-competitive inhibitors
Inhibitor binds enzyme someplace other than s-site. Vmax is lowered. Km is the same
39
uncompetitive inhibitors
inhibitor only binds to the ES complex. both the Vmax and Km will decrease but the slope stays the same.
40
Lineweaver-Burk transformation
plotting the velocity vs substrate concentration gives us hyperbolic curve Y intercept = 1/Vmax X intercept = -1/Km slope is Km/Vmax
41
feedback loops
as product forms, apparent rate of enzymes decreases
42
genetic regulation
Activation of gene expression, increased enzyme (protein) production
43
Allosteric modification
Binding of regulators to sites outside of the active site (allosteric sites) induces conformational. Doesn't follow Michaelis mention/ yields a sigmoidal shape
44
Cooperativity in allosteric enzymes
Substrate binding in one subunit increases the chance of substrate binding in another
45
Allosteric inhibitors
tend to bind more tightly to T state
46
Allosteric activators
tend to bind more tightly to R state
47
covalent modification
Extremely common way to quickly adjust activity of enzymatic reactions. Usually reversible.