Biochemistry Lecture: Enzymes and Catalysts
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Questions and Answers

What is the compound on which an enzyme acts called?

  • Apoenzyme
  • Substrate (correct)
  • Holoenzyme
  • Cofactor

What is a holoenzyme composed of?

  • Apoenzyme alone
  • Apoenzyme together with its cofactors (correct)
  • Cofactors alone
  • Substrate alone

Where does the catalysis occur in an enzyme?

  • Active site (correct)
  • Apoenzyme
  • Substrate
  • Cofactor

What is the term used for the energy barrier that substrates need to overcome before a reaction will occur?

<p>Activation energy (C)</p> Signup and view all the answers

How do enzymes affect the activation energy required for a reaction?

<p>Decrease it (B)</p> Signup and view all the answers

What happens to the energy barrier required for a reaction when enzymes are present?

<p>It decreases (A)</p> Signup and view all the answers

Which type of enzymatic action involves breaking a single structure into smaller components or joining two or more substrate molecules together?

<p>Mechanism of action (C)</p> Signup and view all the answers

What are small organic molecules that act as cofactors for enzymes called?

<p>Coenzymes (D)</p> Signup and view all the answers

Which family of enzymes assists in the breakdown of carbohydrates?

<p>Amylases (B)</p> Signup and view all the answers

What type of specificity describes an enzyme that acts on molecules with specific functional groups such as amino, phosphate, and methyl groups?

<p>Group specificity (B)</p> Signup and view all the answers

Which model explains the enzyme-substrate interaction where the enzyme changes its shape for substrate binding?

<p>Induced-fit model (B)</p> Signup and view all the answers

What term is used to describe enzymes that contain tightly bound metal ions?

<p>Metalloenzymes (D)</p> Signup and view all the answers

Which type of enzymatic specificity describes an enzyme that acts on a particular steric or optical isomer?

<p>Stereochemical specificity (C)</p> Signup and view all the answers

What are tightly bound cofactors called when they perform functions similar to those of prosthetic groups?

<p>Prosthetic groups (C)</p> Signup and view all the answers

Enzymes that require metal ions as loosely bound cofactors are termed as?

<p>Metal-activated enzymes (C)</p> Signup and view all the answers

What are examples of metal ions that can serve as cofactors for enzymes?

<p>Mg and Zn (A)</p> Signup and view all the answers

Study Notes

Enzyme Basics

  • The compound on which an enzyme acts is called a substrate.
  • A holoenzyme is composed of an enzyme and its cofactor(s), which may be metal ions or organic molecules.
  • Catalysis in an enzyme occurs at the active site, where substrate binding takes place.

Activation Energy

  • The energy barrier substrates must overcome for a reaction to occur is known as activation energy.
  • Enzymes lower the activation energy required, facilitating biological reactions by speeding up their rates.
  • When enzymes are present, the energy barrier for a reaction decreases, enhancing the likelihood of reaction occurrences.

Enzyme Action Types

  • Lyase action breaks a single structure into smaller components, while ligase action joins two or more substrate molecules.
  • Small organic molecules that act as cofactors for enzymes are referred to as coenzymes.

Enzyme Classification

  • Amylases are a family of enzymes that assist in the breakdown of carbohydrates.
  • Group specificity describes enzymes that act on molecules with specific functional groups, such as amino, phosphate, and methyl groups.

Enzyme Interaction Models

  • The induced fit model explains enzyme-substrate interactions, suggesting that the enzyme alters its shape upon substrate binding.
  • Enzymes containing tightly bound metal ions are termed metalloenzymes.

Cofactor Types

  • Absolute specificity describes enzymes that act on a particular steric or optical isomer.
  • Tightly bound cofactors performing functions similar to prosthetic groups are called prosthetic groups.
  • Enzymes requiring metal ions as loosely bound cofactors are known as metal-activated enzymes.

Metal Ions as Cofactors

  • Common examples of metal ions serving as cofactors include zinc, iron, and magnesium.

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Description

Learn about enzymes, their role as biocatalysts, the concept of substrate, and the composition of a holoenzyme in this biochemistry lecture.

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