Exam #3 Flashcards Preview

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Flashcards in Exam #3 Deck (183)
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121

How do enzymes work?

They will reduce the activation energy, allowing reactants to go to products at the ambient temperature of the cell

122

____ __ is unaffected by enzyme.

Delta G

123

Delta G is the change in energy from the _______ to the ______.

reactant, product

124

Enzymes reduce Ea without altering _____ __.

Delta G

125

By recognizing that enzyme doesn't alter delta G, we're saying it doesn't change the need for energy that _________ reactions have. Endergonic reactions where the reactant is here, and the product is here. This reaction has a delta G that is positive. Adding the enzyme doesn't take you there.

endergonic

126

The enzyme doesn't provide energy to a reaction that _______ it. If you're endergonic, you need a source of energy, ATP...and you need an ______ so that it happens quickly. So these are two separate requirements...the need for energy in a non spontaneous process...and the need for catalysis, so it happens quickly.

requires, enzyme

127

Do enzymes provide energy?

No, they lower Ea.

128

Who couples the endergonic to the exergonic?

Enzymes.

129

Enzymes enable ________.

coupling

130

Enzymes are ________. It is a requirement of a true catalyst.

reusable

131

T/F: An enzyme can be turned on and off. It's regulated.

TRUE

132

Enzymes are a type of _______.

Protein...typically...

133

What other alternative is there for an enzyme? Besides a protein...

Nucleic acids...can also serve as a catalyst. More specifically **RNA**
***RNA can be an enzyme***

134

The _______ is the reactant that binds to the enzyme.

substrate

135

Where it binds to the enzyme is called the _______ site.

active. It's where the reaction is catalyzed.

136

Enzymes often end in -____.

-ase

137

Sucrase is the specific hydrolase that hydrolyzes _______.

sucrose

138

How does the substrate bind to the active site? It binds how?

binds by weak interactions, forming an enzyme-substrate complex

139

Once the products of glucose and fructose are released, the enzyme is _______.

reused/recycled

140

How do enzymes accomplish this reduction of the Ea? What is actually happening to do that? (3)

Depends on the Enzyme...
1) Some enzymes will orient substrates so that the reaction can happen
2) Stress covalent bonds so that they may be broken
-That's what sucrase does to sucrose, the bond has been bent, which makes it easier to break the bond
3) Create a microenvironment
-You can get the electrons to begin to flow in the direction to allow the reaction to happen

141

T/F: Enzymes make endergonic reactions exergonic.

FLASE!!! Recall, if a reaction is endergonic, you need energy. You need fuel. You need another reaction that is exergonic so that it can be coupled. In addition to that, you need the enzyme which is what couples the reaction and makes it fast.
So the enzyme couples reactions, and speeds it up.

142

As the substrate concentration increases, the reaction rate _______.

increases. If there is more substrate, it will more often find and bind to the enzyme and convert to product more quickly

143

T/F: As long as you give more substrate, the reaction will always go faster.

FALSE! Once you're at a concentration that you've filled every single active site, the rate of the reaction will no longer increase

144

When you effectively max out the capacity of the enzyme. We say that the enzyme is then __________.

saturated

145

Is there anything we can do once the enzyme is saturated to make it go faster?

Add more enzyme, which will provide more active sites for the substrates to bind to

146

As the concentration of enzyme increases, so the ________ rate.

reaction

147

As the temperature increases, the reaction rate ________.

Increases

148

Our _____ temperature is the maximum rate for enzymes.

body

149

After 37 degrees C (98.6 deg F), the reaction rate drops off quickly. Why?

Denaturation of protein. If the temperature goes too high, you will break the weak interactions and the protein will unfold. There's no active site if the enzyme is denatured.

150

Every enzyme has an optimal _________.

Temperature. Every enzyme has an optimal temperature where they operate most efficiently