Life Sciences - Term 3 - Week 8

Enzymes are biological catalysts that speed up chemical reactions in living organisms. They are typically proteins that lower the activation energy required for a reaction to occur, allowing metabolic processes to happen more efficiently. Each enzyme is specific to a particular substrate, which is the reactant that the enzyme acts upon.

Enzymes work by binding to their substrate at the active site, forming an enzyme-substrate complex. This interaction stabilizes the transition state and reduces the energy needed for the reaction. Once the reaction occurs, the products are released, and the enzyme is free to catalyze another reaction. This process is often described by the 'lock and key' model, where the enzyme (lock) is specific to its substrate (key).

Several factors can influence enzyme activity, including temperature, pH, and substrate concentration. Each enzyme has an optimal temperature and pH at which it functions best. Deviations from these conditions can lead to decreased activity or denaturation of the enzyme. Additionally, increasing substrate concentration can enhance reaction rates up to a certain point, after which the enzyme becomes saturated.

Consider the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen. The reaction can be represented as: 2 H2O2 → 2 H2O + O2. When catalase is present, the reaction occurs rapidly, demonstrating how enzymes can significantly increase the rate of biochemical reactions.

If an enzyme catalyzes a reaction that produces 10 moles of product in 5 minutes, we can calculate the enzyme activity as follows: Activity = moles of product/time = 10 moles/5 minutes = 2 moles/minute. This measurement helps in understanding the efficiency of the enzyme under specific conditions.

In groups, discuss how temperature changes might affect the activity of an enzyme like amylase, which breaks down starch. Consider what happens when the temperature is too low versus too high. Present your findings to the class, focusing on the concept of denaturation and optimal conditions.

Choose an enzyme of your choice and research its function, optimal conditions, and any factors that can inhibit its activity. Prepare a short report or presentation to share with the class, highlighting the importance of this enzyme in metabolic processes.

• To provide energy to cells
• To catalyze biochemical reactions
• To transport molecules across membranes
• To store genetic information

Answer: To catalyze biochemical reactions

Enzymes are biological catalysts that speed up chemical reactions without being consumed in the process.

• Temperature
• pH
• Substrate concentration
• Color of the enzyme

Answer: Color of the enzyme

The color of the enzyme does not influence its activity; however, temperature, pH, and substrate concentration do.

Answer: The 'lock and key' model describes how enzymes are specific to their substrates, fitting together like a key fits into a lock.

This model illustrates the specificity of enzymes for their substrates, emphasizing that only the correct substrate can bind to the enzyme's active site.

• It becomes more active
• It loses its functional shape
• It increases its substrate affinity
• It can still catalyze reactions

Answer: It loses its functional shape

Denaturation alters the enzyme's structure, rendering it unable to bind to its substrate and catalyze reactions.

Answer: The active site is the region on the enzyme where the substrate binds and the reaction occurs.

The active site is crucial for the enzyme's function, as it determines the specificity and catalytic activity of the enzyme.

• Glucose
• DNA
• Amylase
• Hemoglobin

Answer: Amylase

Amylase is an enzyme that catalyzes the breakdown of starch into sugars.