Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Enzymes are biological catalysts that are chemically globular proteins. They increase the rate of biochemical reactions by providing an alternative pathway with a lower activation energy ().
Enzymes are highly specific in their action. For example, the enzyme only catalyses the hydrolysis of urea and no other amide.
The 'Lock and Key' mechanism explains enzyme action: the substrate () fits into the active site of the enzyme () to form an enzyme-substrate complex ().
Enzymes work at optimum conditions: Temperature (around or body temperature) and (around for most human enzymes).
The catalytic activity of enzymes is often enhanced by the presence of non-protein components called co-factors (e.g., metal ions like , ) or organic molecules called co-enzymes (e.g., Vitamins).
Enzymes are extremely efficient; one molecule of an enzyme can transform one million molecules of substrate per minute. For instance, facilitates the reaction of and at a rate of molecules per second.
📐Formulae
💡Examples
Problem 1:
Explain how enzymes affect the activation energy of a reaction and name the enzyme that converts Maltose into Glucose.
Solution:
Enzymes lower the activation energy () required for a reaction to proceed. The enzyme that converts Maltose into Glucose is .
Explanation:
By lowering the energy barrier, a larger fraction of reactant molecules can cross the threshold at a given temperature. The reaction for maltose hydrolysis is: .
Problem 2:
What happens to the activity of an enzyme if the temperature is raised significantly above ?
Solution:
The enzyme becomes denatured and loses its catalytic activity.
Explanation:
Since enzymes are globular proteins, high temperatures disrupt the hydrogen bonds and secondary/tertiary structures. This changes the shape of the active site, meaning the substrate can no longer fit ().