Podcast
Questions and Answers
In general, enzymes are what kinds of molecules?
In general, enzymes are what kinds of molecules?
- Minerals
- Lipids
- Nucleic acids
- Proteins (correct)
- Carbohydrates
Enzymes work by _____
Enzymes work by _____
- Decreasing the potential energy difference between reactant and product
- Adding energy to a reaction
- Increasing the potential energy difference between reactant and product
- Reducing energy of activation (correct)
- Adding a phosphate group to a reactant
An enzyme _____
An enzyme _____
- Can bind to nearly any molecule
- Is an organic catalyst (correct)
- Is a source of energy for endergonic reactions
- Increases the energy of activation of a reaction
- Is an inorganic catalyst
What name is given to the reactants in an enzymatically catalyzed reaction?
What name is given to the reactants in an enzymatically catalyzed reaction?
As a result of its involvement in a reaction, an enzyme _____
As a result of its involvement in a reaction, an enzyme _____
In a graph of energy vs reactants and products, what part of the parabola is the energy of activation found?
In a graph of energy vs reactants and products, what part of the parabola is the energy of activation found?
What must be overcome in order for a reaction to proceed?
What must be overcome in order for a reaction to proceed?
Define an exergonic reaction.
Define an exergonic reaction.
If exergonic reactions occur spontaneously, what keeps molecules from breaking apart and cell chemistry from racing out of control?
If exergonic reactions occur spontaneously, what keeps molecules from breaking apart and cell chemistry from racing out of control?
How does a living cell overcome the energy barrier for its metabolic reactions?
How does a living cell overcome the energy barrier for its metabolic reactions?
An enzyme serves as a ___________, ___________ without __________.
An enzyme serves as a ___________, ___________ without __________.
Is an enzyme selective or nonselective?
Is an enzyme selective or nonselective?
Why is an enzyme so specific?
Why is an enzyme so specific?
What is the substrate?
What is the substrate?
What is the active site?
What is the active site?
In a graph of enzymatic activity, what is the most reasonable explanation for low activity at 0 degrees Celsius?
In a graph of enzymatic activity, what is the most reasonable explanation for low activity at 0 degrees Celsius?
How many active sites are generally found in an enzyme?
How many active sites are generally found in an enzyme?
What happens to enzymes as the substrate concentration increases?
What happens to enzymes as the substrate concentration increases?
What happens to the rate of a reaction involving an enzyme when saturation is reached?
What happens to the rate of a reaction involving an enzyme when saturation is reached?
In a graph of reaction rate vs substrate concentration, at what point does the reaction rate remain constant?
In a graph of reaction rate vs substrate concentration, at what point does the reaction rate remain constant?
When saturation is reached, the reaction rate is independent of what?
When saturation is reached, the reaction rate is independent of what?
In a graph of reaction rate vs substrate concentration, in which region is the enzyme saturated with substrate?
In a graph of reaction rate vs substrate concentration, in which region is the enzyme saturated with substrate?
What is your best option for increasing the rate of the reaction when the enzyme is saturated?
What is your best option for increasing the rate of the reaction when the enzyme is saturated?
What are enzyme inhibitors?
What are enzyme inhibitors?
What are the two classifications of enzyme inhibitors?
What are the two classifications of enzyme inhibitors?
What are the two types of reversible enzyme inhibitors?
What are the two types of reversible enzyme inhibitors?
What is a competitive inhibitor?
What is a competitive inhibitor?
What is a noncompetitive inhibitor?
What is a noncompetitive inhibitor?
What does an irreversible inhibitor do?
What does an irreversible inhibitor do?
The competitive inhibitor competes with the substrate for the _____ on an enzyme.
The competitive inhibitor competes with the substrate for the _____ on an enzyme.
What happens to the enzyme's shape when a noncompetitive inhibitor is bonded?
What happens to the enzyme's shape when a noncompetitive inhibitor is bonded?
Enzyme inhibitors disrupt normal interactions between an enzyme and its _____
Enzyme inhibitors disrupt normal interactions between an enzyme and its _____
How can you decrease the effect of the competitive inhibitors?
How can you decrease the effect of the competitive inhibitors?
What do noncompetitive inhibitors do?
What do noncompetitive inhibitors do?
What do irreversible inhibitors do?
What do irreversible inhibitors do?
What is an example of competitive inhibitors?
What is an example of competitive inhibitors?
You have an enzymatic reaction at the optimum pH and temperature. You add a competitive inhibitor and notice the reaction slows down. What can you do to speed the reaction up again?
You have an enzymatic reaction at the optimum pH and temperature. You add a competitive inhibitor and notice the reaction slows down. What can you do to speed the reaction up again?
The phosphorylation of glucose to generate glucose-6-phosphate is catalyzed by hexokinase. This enzyme is allosterically inhibited by its own product, glucose-6-phosphate. This is an example of _____
The phosphorylation of glucose to generate glucose-6-phosphate is catalyzed by hexokinase. This enzyme is allosterically inhibited by its own product, glucose-6-phosphate. This is an example of _____
Feedback inhibition is also known as _____
Feedback inhibition is also known as _____
Which of the following best describes a metastable state?
Which of the following best describes a metastable state?
What is the site on an enzyme that will bind the substrate called?
What is the site on an enzyme that will bind the substrate called?
Which of the following is an enzyme?
Which of the following is an enzyme?
The EC system for naming enzymes is based on which of the following criteria?
The EC system for naming enzymes is based on which of the following criteria?
What may substrate activation involve?
What may substrate activation involve?
The induced-fit model involves what?
The induced-fit model involves what?
Which of the following is not a means of enzyme regulation?
Which of the following is not a means of enzyme regulation?
Covalent modification affects the activity of an enzyme by _____
Covalent modification affects the activity of an enzyme by _____
Study Notes
Enzymes as Biological Catalysts
- Enzymes are primarily proteins that act as organic catalysts to accelerate biochemical reactions without being consumed.
- They work by reducing the energy of activation (EA), allowing reactions to proceed more easily.
Substrates and Active Sites
- The reactants in enzymatically catalyzed reactions are called substrates.
- The active site is the specific region of the enzyme where substrates bind through weak chemical interactions.
Reaction Dynamics
- Enzymes remain unchanged after reactions, meaning they can catalyze subsequent reactions.
- Increasing substrate concentration typically enhances reaction rates until saturation occurs, at which point all active sites are occupied.
Energy Considerations
- Even spontaneous reactions (exergonic) require an initial energy input (energy of activation) to start.
- A low reaction rate at temperatures below optimal levels often indicates insufficient energy for the reaction to proceed.
Specificity of Enzymes
- Enzymes exhibit high specificity due to their unique three-dimensional structures, allowing them to interact only with particular substrates.
- Competitive inhibitors resemble substrates and bind to the active site, while non-competitive inhibitors attach elsewhere, altering the enzyme's shape.
Inhibition Types
- Irreversible inhibitors form covalent bonds with enzymes, permanently inactivating them.
- Reversible inhibitors can be competitive or non-competitive, affecting enzyme activity without permanent changes.
Regulation of Enzymatic Activity
- Feedback inhibition occurs when a product of a metabolic pathway inhibits an enzyme involved in its own synthesis, maintaining metabolic balance.
- Enzyme activity can be modulated by processes such as allosteric regulation and covalent modification (e.g., adding phosphate groups).
Metastable States and Catalysis
- The metastable state reflects a condition where substrate reactions can occur but typically require a catalyst to overcome energy barriers.
- The induced-fit model illustrates how enzyme conformations change in response to substrate binding, enhancing catalytic efficiency.
Enzyme Classification
- Enzymes are categorized into six major classes based on their functions, according to the Enzyme Commission (EC) system.
- Examples of enzymes include carboxypeptidase A, a well-characterized proteolytic enzyme.
Practical Implications
- Competitive inhibitors can be outcompeted by increasing substrate concentration.
- Enzyme regulation is essential for cellular function, and understanding these mechanisms informs drug development and metabolic engineering.
Studying That Suits You
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Description
Test your knowledge on enzymes and their functions with this flashcard quiz based on Chapter 6 of Biology. Discover how enzymes act as catalysts in biochemical reactions and learn about their properties and mechanisms. Perfect for preparing for your upcoming biology exam!
