Enzymes

• What are enzymes?

  Enzymes are globular proteins that act as catalysts.
• How do catalysts affect chemical reactions?

  Catalysts alter the rate of a chemical reaction without undergoing permanent changes themselves.
• Why are enzymes effective in small amounts?

  Because they can be reused repeatedly.
• What do enzymes do to reactions that already occur?

  They speed up reactions that already occur.
• What is activation energy?

  Activation energy is the minimum amount of energy needed to activate a reaction.
• How do enzymes lower activation energy?

  Enzymes work by lowering the activation energy level.
• Why are enzymes important for metabolic processes in the human body?

  They allow reactions to take place at a lower temperature than normal.
• What are the learning objectives related to enzyme action?

  • Explain how enzymes speed up chemical reactions.
  • Describe how the structure of enzyme molecules relates to their function.
  • Explain the lock and key model of enzyme action.
  • Explain the induced-fit model of enzyme action.
• What is the molecule on which an enzyme acts called?

  The molecule is called the substrate.
• What forms when a substrate fits into the active site of an enzyme?

  An enzyme-substrate complex forms.
• What is the active site of an enzyme?

  The active site is a specific region of the enzyme made up of a small number of amino acids.
• How does the induced fit model describe enzyme action?

  The induced fit model proposes that the active site forms as the enzyme and substrate interact.
• What happens to the enzyme during the induced fit process?

  The enzyme changes shape to mold around the substrate.
• What is the lock and key model of enzyme action?

  The lock and key model suggests that a substrate fits exactly into the active site of an enzyme like a key fits into a lock.
• What is a limitation of the lock and key model?

  The model considers the enzyme to be a rigid structure, which is not accurate.
• What are the factors affecting enzyme action?

  • Temperature
  • pH
  • Substrate concentration
  • Enzyme concentration
• How is the rate of an enzyme-controlled reaction measured?

  By measuring the time-course of the reaction, such as the formation of products or disappearance of substrates.
• What happens to the rate of reaction as substrate concentration decreases?

  The rate of reaction slows down as there are fewer substrate molecules available.
• What effect does temperature have on enzyme activity?

  A rise in temperature increases the kinetic energy of molecules, leading to more effective collisions.
• What happens to enzymes at high temperatures?

  High temperatures can cause the hydrogen and other bonds in the enzyme to break, changing its shape.
• Why is it important to keep other variables constant when measuring the effect of one variable on enzyme activity?

  To ensure that any changes in the rate of reaction are due to the variable being tested.
• What is the relationship between the active site and the substrate?

  The active site and the substrate are complementary in shape.
• What is the significance of the enzyme-substrate complex?

  It is crucial for the enzyme to catalyze the reaction and lower the activation energy.
• How does the presence of product molecules affect the rate of reaction?

  Product molecules may hinder substrate molecules from reaching the active site, slowing the reaction.
• What happens to the rate of reaction when all substrate has been used up?

  The rate of reaction flattens out because no new product can be produced.
• What is the purpose of measuring the gradient of a curve in enzyme-catalyzed reactions?

  The gradient indicates the rate of change at a specific point in the reaction.
• What is the normal line in relation to measuring the gradient of a curve?

  The normal line is a line that passes through a point at a 90° angle to the curve.
• Why is it necessary to have an initial input of energy for a reaction?

  To overcome the activation energy barrier and start the reaction.
• How does the induced fit model improve upon the lock and key model?

  The induced fit model accounts for the flexibility of the enzyme's structure during substrate interaction.
• What is the role of hydrogen bonds in enzyme function?

  Hydrogen bonds help maintain the enzyme's shape, which is crucial for its function.
• What is the significance of the enzyme's 3-D shape?

  The 3-D shape determines the enzyme's active site and its ability to interact with substrates.
• How do enzymes determine the structures and functions of living matter?

  By catalyzing a wide range of reactions both inside and outside the cell.
• What is the relationship between enzyme concentration and reaction rate?

  Higher enzyme concentration generally increases the rate of reaction, provided substrate is available.
• What happens to enzyme activity when pH levels are altered?

  Changes in pH can denature the enzyme, affecting its activity.
• Why is it important for enzymes to come into physical contact with their substrates?

  Physical contact is necessary for the formation of enzyme-substrate complexes.
• What is the effect of substrate concentration on enzyme activity?

  Increased substrate concentration generally increases the rate of reaction until the enzyme becomes saturated.
• How does the structure of an enzyme relate to its function?

  The specific 3-D shape of an enzyme allows it to bind to its substrate effectively.
• What is the significance of the enzyme-substrate complex in catalysis?

  The enzyme-substrate complex is essential for lowering the activation energy and facilitating the reaction.
• How does the induced fit model explain the flexibility of enzymes?

  The induced fit model shows that enzymes can change shape to accommodate the substrate during binding.
• What happens to the rate of reaction as the substrate is consumed?

  The rate of reaction decreases as the substrate is consumed and fewer substrate molecules are available.