3.1. Explain the function of enzymes

This guide will help you answer 3.1. Explain the function of enzymes.

Enzymes play a central role in the human body and other living organisms. These substances are biological catalysts, which means they speed up chemical reactions. Without enzymes, many essential processes would happen too slowly to sustain life.

What are Enzymes?

Enzymes are proteins. Proteins are made of long chains of amino acids folded into unique shapes. This shape is essential for the enzyme to perform its role. Each enzyme’s specific shape allows it to bind to particular molecules that fit like a key in a lock.

Active Site and Substrates

The “active site” is a specially shaped area on an enzyme. This is where the “substrate”—the molecule an enzyme acts on—binds. For example:

• An enzyme that works on lactose (a type of sugar) has an active site designed specifically for lactose molecules.
• When the substrate binds to the active site, a chemical reaction occurs, and the enzyme helps turn the substrate into a new product.

The unique fit between an enzyme and its substrate is often called the “lock and key model.”

How Enzymes Speed Up Reactions

Enzymes reduce the “activation energy” needed for a reaction to happen. Activation energy is the minimum amount of energy required to start a chemical reaction. By lowering this barrier, enzymes make reactions occur faster and with less effort.

Example of Enzyme Action

A good example is the enzyme amylase, found in saliva. Amylase speeds up the breakdown of starch into smaller sugars. Without this enzyme, digesting starch would take much longer and require a lot more energy.

Enzymes in the Digestive System

The human digestive system relies heavily on enzymes. These enzymes break down large food molecules into smaller ones that the body can absorb. Key examples include:

• Proteases: Break down proteins into amino acids.
• Lipases: Break down fats into glycerol and fatty acids.
• Carbohydrases: Break down carbohydrates into simple sugars.

Each of these enzymes has a specific role and works in a particular part of the digestive system, such as the stomach or small intestine.

Enzymes Are Reusable

One remarkable feature of enzymes is that they are not used up in chemical reactions. After completing one reaction, an enzyme can go on to catalyse another one. This reusability is important because it makes enzymes highly efficient.

Factors Affecting Enzyme Activity

Several factors can impact how well an enzyme works. These include:

• Temperature: Most enzymes work best at body temperature (around 37°C). If the temperature is too high or too low, the enzyme may stop working.
• pH levels: Different enzymes work at different pH levels. Stomach enzymes, like pepsin, need an acidic environment, whereas other enzymes require a neutral or slightly alkaline pH.
• Substrate concentration: The amount of substrate can affect how quickly an enzyme works. Too much or too little substrate can alter the reaction rate.
• Inhibitors: Some chemicals can block an enzyme’s active site, stopping it from working.

Denaturation

Enzymes are sensitive to changes in temperature and pH. When exposed to extreme conditions, they can become “denatured.” This means their structure changes, and the active site no longer fits the substrate. A denatured enzyme cannot function.

Medical and Industrial Uses

Enzymes are not just vital for life; they are also useful in medicine and industry. In medicine, enzymes are part of treatments for specific conditions, such as:

• Lactose intolerance: Enzymes like lactase can help people digest lactose found in milk.
• Clotting disorders: Some enzymes help break down blood clots in patients.

In industry, enzymes are used in:

• Cleaning products, such as laundry detergents, to break down stains.
• Food production, such as brewing and cheese-making.
• Biofuel manufacture, where enzymes help break down plant material.

Enzyme Inhibition

Inhibitors are substances that reduce or stop enzyme activity. They can be:

• Competitive inhibitors: These attach to the active site, blocking the substrate.
• Non-competitive inhibitors: These bind somewhere else on the enzyme, changing its shape.

Inhibitors are often used in medicine to treat illnesses. For example, some drugs inhibit enzymes that bacteria need to survive, helping to fight infection.

Enzyme Deficiency and Disease

When enzymes do not function properly, it can lead to health problems. For example:

• A deficiency of insulin (technically an enzyme-like protein) causes diabetes.
• Missing or malfunctioning digestive enzymes can cause problems like coeliac disease or lactose intolerance.

Enzymes in Everyday Life

Enzymes are everywhere around us. Many of the processes we take for granted in both our bodies and the wider world depend on enzymes. From the creation of bread through yeast fermentation to the way plants grow using photosynthesis, enzymes make it all possible.

Final Thoughts

Enzymes are:

• Biological catalysts.
• Specific to their substrate.
• Important for speeding up necessary reactions.
• Sensitive to their environment (temperature and pH).
• Essential for life and useful in medical and industrial applications.

Talking about their structure and function in straightforward terms helps us see how indispensable they are for life. Once we understand their role in the body, it’s easier to appreciate why they are at the core of so many biological and technological processes.