Enzymes: Catalysts of Life

Biology Grades High School 8:12 Video
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Lesson Description

This lesson explores the vital role of enzymes in biological systems. We will examine how enzymes act as catalysts to accelerate reactions, focusing on substrates, active sites, induced fit, and activation energy. Students will gain an understanding of enzyme structure and function, and their importance in maintaining life processes.

Video Resource

Enzymes | Energy and enzymes | Biology | Khan Academy

Khan Academy

Duration: 8:12
Watch on YouTube

Key Concepts

  • Enzymes as biological catalysts
  • Activation energy and how enzymes lower it
  • Substrates and active sites
  • Induced fit model of enzyme-substrate interaction
  • Enzyme structure (proteins) and environmental factors (pH, temperature)

Learning Objectives

  • Define enzymes and explain their role as catalysts in biological reactions.
  • Describe how enzymes lower activation energy to speed up reactions.
  • Identify and describe the functions of substrates, active sites, and the induced fit model.
  • Explain the impact of pH and temperature on enzyme activity.
  • Relate enzyme structure to its function.

Educator Instructions

  • Introduction (5 mins)
    Begin by asking students what they know about enzymes. Briefly discuss the importance of chemical reactions in living organisms.
  • Video Viewing (15 mins)
    Play the Khan Academy video "Enzymes | Energy and enzymes | Biology | Khan Academy". Instruct students to take notes on key terms and concepts as they watch.
  • Discussion (15 mins)
    Lead a class discussion based on the discussion questions below. Encourage students to share their understanding of enzymes and related concepts.
  • Interactive Exercise: Enzyme Modeling (15 mins)
    Students will model enzyme function using provided materials. Details below.

Interactive Exercises

  • Enzyme Modeling
    Students will work in small groups. Each group will receive materials like playdough, paper clips, and pipe cleaners. They will use these materials to create a model of an enzyme with an active site and a substrate. Students should demonstrate how the enzyme binds to the substrate (induced fit) and how this interaction facilitates a reaction. Each group will present their model and explain its function to the class.

Discussion Questions

  • What is a catalyst, and why are enzymes considered biological catalysts?
  • How does an enzyme affect the activation energy of a reaction?
  • Describe the relationship between an enzyme, its substrate, and the active site.
  • Explain the induced fit model and its importance in enzyme function.
  • How can changes in temperature or pH affect enzyme activity?

Skills Developed

  • Critical thinking
  • Scientific communication
  • Model building
  • Data interpretation
  • Visual Learning

Multiple Choice Questions

Question 1:

Which of the following is the primary role of an enzyme?

Correct Answer: To catalyze biological reactions

Question 2:

What is the term for the energy required to start a chemical reaction?

Correct Answer: Activation energy

Question 3:

The specific region of an enzyme where the substrate binds is called the:

Correct Answer: Active site

Question 4:

What is the 'induced fit' model of enzyme action?

Correct Answer: The substrate changes the shape of the enzyme's active site for optimal binding.

Question 5:

Enzymes are primarily composed of:

Correct Answer: Proteins

Question 6:

What is the term for a molecule that an enzyme acts upon?

Correct Answer: Substrate

Question 7:

Hexokinase is an enzyme that facilitates which reaction?

Correct Answer: Phosphorylation of glucose

Question 8:

Which of the following factors can affect enzyme activity?

Correct Answer: Temperature and pH

Question 9:

What happens to an enzyme after it catalyzes a reaction?

Correct Answer: It can be used again

Question 10:

In the phosphorylation of glucose, what molecule donates the phosphate group?

Correct Answer: ATP

Fill in the Blank Questions

Question 1:

A substance that speeds up a chemical reaction is called a(n) ________.

Correct Answer: catalyst

Question 2:

Enzymes lower the ________ ________ of a reaction.

Correct Answer: activation energy

Question 3:

The molecule that binds to an enzyme is called the ________.

Correct Answer: substrate

Question 4:

The part of the enzyme where the substrate binds is called the ________ ________.

Correct Answer: active site

Question 5:

The model describing the interaction between the enzyme and substrate, where the enzyme changes shape slightly for optimal binding, is called ________ ________.

Correct Answer: induced fit

Question 6:

Enzymes are a type of ________ macromolecule.

Correct Answer: protein

Question 7:

An enzyme called ________ helps with phosphorylation of a sugar molecule.

Correct Answer: hexokinase

Question 8:

Enzymes work optimally in specific ________ and ________ ranges.

Correct Answer: pH, temperature

Question 9:

When an enzyme loses its shape due to high temperatures, it is said to be ________.

Correct Answer: denatured

Question 10:

________ is the molecule that provides the phosphate group during the phosphorylation of glucose.

Correct Answer: ATP

Educational Standards

B.LS1.1:Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins, which carry out the essential functions of life through systems of specialized cells. B.LS1.6:Construct and revise an explanation based on evidence for how carbon, hydrogen, and oxygen from sugar molecules may combine with other elements to form amino acids and/or other large carbon-based molecules.

Teaching Materials

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