Enzymes Flashcards
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Questions and Answers

What is the substance with which an enzyme reacts?

Substrate

Is an enzyme used up by the reaction it catalyzes?

False

In what way does an enzyme affect the reaction it catalyzes?

An enzyme increases the rate of the reaction.

What is the active site of an enzyme?

<p>The part of the enzyme into which the substrate fits.</p> Signup and view all the answers

What is meant by enzyme specificity?

<p>The active site has a complex configuration with which only one substrate molecule fits.</p> Signup and view all the answers

Could life exist without enzymes?

<p>False</p> Signup and view all the answers

At what temperature is enzyme activity the greatest?

<p>About 37 degrees Celsius.</p> Signup and view all the answers

What is the optimum pH for pepsin?

<p>4.4.</p> Signup and view all the answers

How does increasing enzyme concentration affect the rate of enzyme action when substrate concentration remains constant?

<p>The rate of enzyme action increases at first, but remains constant after a certain point.</p> Signup and view all the answers

How does increasing substrate concentration affect the rate of enzyme action when enzyme concentration remains constant?

<p>The rate of action increases to a certain point, but remains constant afterward.</p> Signup and view all the answers

How do enzymes help accelerate reactions?

<p>Enzymes lower the activation energy needed for a chemical reaction.</p> Signup and view all the answers

What are the characteristics of enzymes?

<p>Enzymes are usually proteins that speed up chemical reactions.</p> Signup and view all the answers

What is the relationship among enzymes, energy, and reaction rates?

<p>Enzymes speed up reactions by lowering the activation energy.</p> Signup and view all the answers

Why do cells use different enzymes to catalyze different reactions?

<p>Different reactions require enzymes that are specific to their substrate's shape.</p> Signup and view all the answers

What are enzymes?

<p>Proteins.</p> Signup and view all the answers

Describe an enzyme.

<p>Globular, usually quaternary structure.</p> Signup and view all the answers

What do enzymes permit?

<p>Reactions to proceed under milder conditions.</p> Signup and view all the answers

How are enzymes needed?

<p>In small quantities and can be reused.</p> Signup and view all the answers

What do enzymes enter a reaction with?

<p>They enter into the reaction with the substrate at the active site.</p> Signup and view all the answers

Enzymes are ____.

<p>Specific.</p> Signup and view all the answers

Enzyme actions are ____.

<p>Reversible.</p> Signup and view all the answers

Enzymes have ________.

<p>Optimum pH and temperatures.</p> Signup and view all the answers

Enzymes may be assisted by what?

<p>Coenzymes.</p> Signup and view all the answers

How is the rate of enzyme reaction regulated?

<p>By the relative amounts of enzyme and substrate.</p> Signup and view all the answers

What are the two theoretical models for enzyme-substrate complexes?

<p>Lock and key and induced fit.</p> Signup and view all the answers

What is the lock and key model?

<p>The enzyme and the substrate match up and fit together like puzzle pieces.</p> Signup and view all the answers

What is the induced fit model?

<p>The enzyme adjusts to fit the substrate when it binds to it.</p> Signup and view all the answers

Are all enzymes catalysts?

<p>True</p> Signup and view all the answers

What is a catalyst?

<p>Substances that cause a reaction to occur at a faster rate without being affected.</p> Signup and view all the answers

How do enzymes lower the activation energy?

<p>By providing an alternative reaction pathway.</p> Signup and view all the answers

Increasing the amount of substrate or enzyme will...

<p>Increase the reaction to a point at which it will remain constant.</p> Signup and view all the answers

What is the point of saturation?

<p>The point at which increasing substrate or enzyme concentration no longer increases reaction rate.</p> Signup and view all the answers

Increasing the temperature or pH will...

<p>Increase a reaction to a point at which it will then decrease.</p> Signup and view all the answers

Study Notes

Enzymes Overview

  • Enzymes act as biological catalysts, speeding up chemical reactions without being consumed.
  • They are typically proteins with a globular structure, often having a quaternary configuration.
  • Enzymes are specific to particular substrates due to the unique shape of their active sites, akin to a lock and key.

Substrate and Active Site

  • Substrate: The substance on which an enzyme acts.
  • Active site: The region of the enzyme where the substrate binds, allowing the enzyme-substrate complex to form.

Enzyme Function and Reaction Rates

  • Enzymes increase reaction rates by lowering the activation energy required for reactions.
  • At about 37 degrees Celsius, enzyme activity reaches its peak.
  • Each enzyme has an optimum pH; for example, pepsin operates best at pH 4.4.

Enzyme Specificity and Models

  • Enzymes exhibit specificity; they only catalyze specific reactions based on their active site shape.
  • The "lock and key" model illustrates the specific fit between enzyme and substrate.
  • The "induced fit" model suggests that the enzyme adjusts its shape to better fit the substrate upon binding.

Enzyme Concentration and Substrate Concentration

  • Increasing enzyme concentration enhances the reaction rate to a point, after which it plateaus.
  • Similarly, increasing substrate concentration raises the reaction rate until saturation is achieved, beyond which there is no significant improvement.

Regulatory Factors

  • Enzyme reactions are regulated by the relative amounts of enzymes and substrates present.
  • Enzymes function efficiently under mild conditions, maintaining optimum temperature and pH for activity.

Additional Characteristics

  • Enzymes are used in small quantities and can be reused multiple times.
  • They can be assisted by coenzymes, which are often vitamins necessary for enzyme activity.
  • Enzyme actions are typically reversible, allowing for the conversion between reactants and products.

Importance of Enzymes to Life

  • Without enzymes, biochemical processes would occur too slowly to sustain life.
  • The absence of enzymes means that cellular reactions would fail to reach the necessary rates for metabolic function.

General Properties

  • Enzymes can be classified as catalysts, but not all catalysts qualify as enzymes.
  • Enzymes operate best within specific ranges of temperature and pH, where they maintain their structural integrity without denaturation.

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Description

This quiz features flashcards focused on enzymes, their substrates, and their roles in biochemical reactions. Review key definitions and concepts to enhance your understanding of how enzymes function in catalysis. Perfect for biology students looking to deepen their knowledge of enzymatic processes.

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