BB 450 Unit 2 with verified answers
graded A+
How much do enzymes enhance reaction rates? - correct answer ✔✔They enhance reaction
rates A LOT
Enzymes accelerate the rates of such reactions by well over a million-fold, so reactions that
would take years in the absence of catalysis can occur in fractions of seconds if catalyzed by the
appropriate enzyme.
How much would a chemical catalyst, as opposed to an enzyme, speed it up? - correct answer
✔✔A chemical catalyst could speed things up maybe 1000 fold whereas a enzyme is closer to 1
million fold
So enzymes speed up a reaction faster than an enzymatic catalyst
What is an "active site"? - correct answer ✔✔the active site is the region of an enzyme where
substrate molecules bind and undergo a chemical reaction.
It is where the reaction is catalyzed
Substrates bind to the active site and they are often on clefts.
Where is the substrate binding site of an enzyme? - correct answer ✔✔The active site
How does the reaction work when there are two substrates? What are the steps? (Catalysis
steps) - correct answer ✔✔1. The enzyme and substrates are free (E + S)
,2. The substrate and the enzyme recognize and bind to each other and this forms an enzyme
substrate complex (ES complex)
3. The ES complex brings the substrate closer (conformational shape change) into proximity with
each other which results in a reaction between the two substrates. This is the ES* complex
4. EP Complex: The substrate changes into products
5. E + P: The products are released to go out into the cell and do jobs
How do we denote the complexes, like "ES" and "ES*" etc.? - correct answer ✔✔1. E + S
2. ES
3. ES*
4. EP
5. E + P
Is the enzyme changed by the reaction? - correct answer ✔✔Enzymes are *not* permanently
changed by the reaction but while it is happening there is some conformational changes. But
once it releases the substrate it goes back.
Contrast lock and key with induced fit models? Which is true? - correct answer ✔✔Lock and
Key: This is the older model that posits that there's a substrate that fits into an enzyme and
those shapes are an exact fit. You have to have the exact right shape of substrate or else nothing
will happen. Doesn't take into account any conformational changes that may occur in the
enzyme or even in a substrate.
, Induced Fit: Says that the enzyme changes the shape of the enzyme and vise versa (though it is
a bit transient the way that the enzyme is changed). When the two components bind it creates
a kind of tension/energy to it that will cause an induced fit so that they fit together even better
then they did when they first came in contact
The induced fit model is the more accepted one
How does tension help the induced fit? - correct answer ✔✔Substrate enters the active site of
the enzyme and it clamps down around the substrate forming an induced fit.
The tension helps because it allows for a tighter fit and more contact to occur between the
enzyme and substrate
Tension causes the jaws to close but the resulting change in the shape when product is created
will allow the jaws to open again
What is activation energy? How does it change the energy need for rxn and what does not
change? - correct answer ✔✔Activation Energy: The energy necessary for an uncatalyzed
reaction to occur. The minimum quantity of energy which the reacting species must possess in
order to undergo a specified reaction.
Using an enzyme will lower the activation energy. The *overall* energy of the reaction doesn't
change it's just that the enzyme lowered the energy required to initiate the reaction.
What is equilibrium of a reaction? What is it not? - correct answer ✔✔It IS the point at which
the concentration of the reactants and the products won't change
It is NOT the point at which the concentrations of the reactants and the products won't change
graded A+
How much do enzymes enhance reaction rates? - correct answer ✔✔They enhance reaction
rates A LOT
Enzymes accelerate the rates of such reactions by well over a million-fold, so reactions that
would take years in the absence of catalysis can occur in fractions of seconds if catalyzed by the
appropriate enzyme.
How much would a chemical catalyst, as opposed to an enzyme, speed it up? - correct answer
✔✔A chemical catalyst could speed things up maybe 1000 fold whereas a enzyme is closer to 1
million fold
So enzymes speed up a reaction faster than an enzymatic catalyst
What is an "active site"? - correct answer ✔✔the active site is the region of an enzyme where
substrate molecules bind and undergo a chemical reaction.
It is where the reaction is catalyzed
Substrates bind to the active site and they are often on clefts.
Where is the substrate binding site of an enzyme? - correct answer ✔✔The active site
How does the reaction work when there are two substrates? What are the steps? (Catalysis
steps) - correct answer ✔✔1. The enzyme and substrates are free (E + S)
,2. The substrate and the enzyme recognize and bind to each other and this forms an enzyme
substrate complex (ES complex)
3. The ES complex brings the substrate closer (conformational shape change) into proximity with
each other which results in a reaction between the two substrates. This is the ES* complex
4. EP Complex: The substrate changes into products
5. E + P: The products are released to go out into the cell and do jobs
How do we denote the complexes, like "ES" and "ES*" etc.? - correct answer ✔✔1. E + S
2. ES
3. ES*
4. EP
5. E + P
Is the enzyme changed by the reaction? - correct answer ✔✔Enzymes are *not* permanently
changed by the reaction but while it is happening there is some conformational changes. But
once it releases the substrate it goes back.
Contrast lock and key with induced fit models? Which is true? - correct answer ✔✔Lock and
Key: This is the older model that posits that there's a substrate that fits into an enzyme and
those shapes are an exact fit. You have to have the exact right shape of substrate or else nothing
will happen. Doesn't take into account any conformational changes that may occur in the
enzyme or even in a substrate.
, Induced Fit: Says that the enzyme changes the shape of the enzyme and vise versa (though it is
a bit transient the way that the enzyme is changed). When the two components bind it creates
a kind of tension/energy to it that will cause an induced fit so that they fit together even better
then they did when they first came in contact
The induced fit model is the more accepted one
How does tension help the induced fit? - correct answer ✔✔Substrate enters the active site of
the enzyme and it clamps down around the substrate forming an induced fit.
The tension helps because it allows for a tighter fit and more contact to occur between the
enzyme and substrate
Tension causes the jaws to close but the resulting change in the shape when product is created
will allow the jaws to open again
What is activation energy? How does it change the energy need for rxn and what does not
change? - correct answer ✔✔Activation Energy: The energy necessary for an uncatalyzed
reaction to occur. The minimum quantity of energy which the reacting species must possess in
order to undergo a specified reaction.
Using an enzyme will lower the activation energy. The *overall* energy of the reaction doesn't
change it's just that the enzyme lowered the energy required to initiate the reaction.
What is equilibrium of a reaction? What is it not? - correct answer ✔✔It IS the point at which
the concentration of the reactants and the products won't change
It is NOT the point at which the concentrations of the reactants and the products won't change
