GCSE Biology - Enzymes - How Temperature and pH Affect Rate of Reaction

Cognito

1 May 202203:37

Summary

TLDRThis video explains how temperature and pH affect enzyme activity and the rate of enzyme-controlled reactions. It highlights that increasing temperature initially boosts the reaction rate due to higher kinetic energy but beyond a certain point (around 37°C), the enzyme becomes denatured and loses function. Similarly, deviations in pH from the enzyme’s optimal range can cause denaturation. The video also introduces key terms like 'optimum temperature' and 'optimum pH,' and provides examples such as stomach enzymes functioning best in acidic conditions. Viewers are invited to explore more on the accompanying learning platform.

Takeaways

🌡️ Temperature affects enzyme activity: higher temperatures increase the reaction rate up to a point.
⚡ Increased kinetic energy at higher temperatures makes particles collide more often, speeding up the reaction.
🌡️ Above 37°C, the enzyme's bonds start to break, altering the shape of the active site.
🛑 At 45°C, enzymes become denatured, meaning they can't function anymore, and the damage is permanent.
🎯 The optimal temperature for enzyme activity is 37°C, where the reaction rate is highest.
🔄 Each enzyme has a specific optimal temperature that varies depending on its environment.
🧪 pH also influences enzyme function; too high or too low pH decreases the reaction rate.
🔗 Like temperature, pH can break bonds in enzymes, changing their active site and slowing down reactions.
❌ Extreme changes in pH can denature enzymes, rendering them unable to catalyze reactions.
📊 Enzymes in the human body generally have an optimal pH of 7, but stomach enzymes work best at pH 2.

Q & A

What happens to the rate of an enzyme-controlled reaction as the temperature increases initially?
-As the temperature increases initially, the rate of the enzyme-controlled reaction also increases. This is because the particles gain more kinetic energy, making collisions between enzymes and substrates more likely.
Why does the rate of reaction decrease after 37°C?
-The rate of reaction decreases after 37°C because high temperatures begin to break the bonds holding the enzyme's structure together. This causes the enzyme's active site to change shape, reducing its ability to bind with the substrate, eventually leading to denaturation.
What is the term used when an enzyme permanently loses its ability to function due to high temperatures?
-The term used is 'denatured.' When an enzyme becomes denatured, its structure changes permanently, and it can no longer bind to the substrate, even if the temperature is lowered.
At what temperature does the enzyme in the video become denatured?
-In the video, the enzyme becomes denatured at around 45°C.
What is meant by the 'optimum temperature' for an enzyme?
-The 'optimum temperature' is the temperature at which the enzyme's rate of reaction is highest. For most human enzymes, this is around 37°C.
How does pH affect enzyme activity?
-pH affects enzyme activity by altering the bonds holding the enzyme together. If the pH is too high or too low, it can change the shape of the enzyme's active site, reducing its ability to bind with substrates and ultimately denaturing the enzyme.
What happens to the enzyme's active site when pH levels are outside the optimal range?
-When pH levels are outside the optimal range, the enzyme's active site starts to change shape. Initially, the substrate can still fit but less efficiently, slowing the reaction. Eventually, the active site changes so much that the substrate can no longer bind, and the enzyme becomes denatured.
What is the optimal pH for most enzymes in the human body?
-The optimal pH for most enzymes in the human body is around neutral, or pH 7.
Why do enzymes in the stomach have a different optimal pH than other enzymes in the body?
-Enzymes in the stomach have an optimal pH of around 2 because they need to function in the stomach's highly acidic environment, unlike other enzymes that operate in more neutral conditions.
Can an enzyme regain its function if the temperature is lowered after it has been denatured?
-No, once an enzyme has been denatured due to high temperatures, the damage is permanent, and it cannot regain its function even if the temperature is lowered.

Outlines

00:00

🌡️ The Effect of Temperature on Enzyme Activity

This section explains how temperature influences enzyme-controlled reactions. It describes how the rate of reaction increases with rising temperature due to increased kinetic energy, leading to more frequent collisions between particles. However, after 37°C, the rate of reaction decreases because high temperatures begin to break bonds in the enzyme, causing the active site to change shape. If the enzyme changes shape too much, it becomes denatured, permanently losing its ability to function, even if the temperature is lowered again.

🔥 Denaturation and Optimum Temperature

This part focuses on the concept of denaturation, where an enzyme becomes permanently inactive due to extreme temperatures. The enzyme’s optimal temperature, the point at which its activity is highest, is identified as 37°C in the example. Different enzymes have different optimal temperatures depending on their biological role and environment.

🔬 The Effect of pH on Enzyme Activity

This paragraph covers how pH levels affect enzyme-controlled reactions. If the pH is too high or too low, the rate of reaction decreases as the bonds holding the enzyme together start to break, leading to changes in the active site. Initially, the substrate may still bind, though less effectively, but eventually, the enzyme becomes denatured, rendering it unable to bind the substrate at all.

⚖️ Optimal pH and Its Importance

Here, the optimal pH for enzymes is discussed. The optimal pH varies depending on where the enzyme typically operates. For instance, enzymes in the human body generally have an optimal pH of around 7 (neutral), while enzymes in the stomach work best in more acidic conditions, around pH 2, to function effectively in that environment.

📚 Bonus: Learning Platform Introduction

This closing section introduces the audience to a learning platform. It invites viewers to explore additional educational resources, including videos, practice questions, and progress tracking for both science and math subjects. Viewers can access the platform by clicking on the logo or following the link provided in the video description.

Mindmap

Keywords

💡Enzymes

Enzymes are proteins that act as biological catalysts, speeding up chemical reactions in living organisms. In the video, enzymes are discussed in terms of their activity being affected by temperature and pH. For example, high temperatures can denature enzymes, rendering them ineffective.

💡Denaturation

Denaturation refers to the process by which an enzyme loses its structure, specifically its active site, due to factors like high temperature or extreme pH. The video highlights how denaturation occurs at around 45°C, permanently damaging the enzyme and stopping it from functioning.

💡Optimum Temperature

Optimum temperature is the temperature at which an enzyme's activity is at its highest. In the video, this is shown as 37°C for most human enzymes. Beyond this point, the enzyme’s activity decreases rapidly due to denaturation.

💡pH

pH is a measure of how acidic or basic a solution is. The video explains that enzymes have an optimal pH at which they function best. For example, enzymes in the stomach work best at a pH of around 2, while most enzymes in the body work at a neutral pH of 7.

💡Active Site

The active site is the part of an enzyme where the substrate binds and the reaction occurs. In the video, it is explained how changes in temperature and pH can alter the shape of the active site, preventing the enzyme from binding to its substrate and catalyzing reactions.

💡Kinetic Energy

Kinetic energy refers to the energy that particles have due to their motion. The video describes how increasing the temperature raises the kinetic energy of particles, making them more likely to collide and react, thus increasing the rate of enzyme-controlled reactions initially.

💡Substrate

A substrate is the substance upon which an enzyme acts. In the video, it is mentioned that the enzyme's ability to bind to its substrate diminishes when the enzyme’s active site changes shape due to factors like extreme temperature or pH.

💡Reaction Rate

Reaction rate refers to the speed at which a chemical reaction occurs. The video discusses how temperature and pH affect the reaction rate of enzyme-controlled processes, increasing it up to a point and then drastically reducing it when the enzyme becomes denatured.

💡Optimal pH

Optimal pH is the specific pH at which an enzyme functions most efficiently. The video explains how different enzymes have different optimal pH levels depending on where they function in the body, such as stomach enzymes that work best at an acidic pH of around 2.

💡Catalysis

Catalysis is the acceleration of a chemical reaction by a catalyst, which in this case is an enzyme. The video discusses how enzymes catalyze reactions by lowering the activation energy, but their effectiveness is dependent on environmental factors like temperature and pH.

Highlights

Introduction to how temperature and pH affect enzyme functioning.

Explanation of the relationship between temperature increase and reaction rate increase due to more kinetic energy.

At around 37°C, the rate of reaction is highest (optimum temperature).

After 37°C, the enzyme rate starts to drop due to denaturation from high temperatures.

Denaturation happens when high temperatures break the bonds holding the enzyme's active site together.

Once denatured, the enzyme cannot bind to the substrate, and the reaction stops.

At around 45°C, the enzyme becomes irreversibly denatured.

Lowering the temperature after denaturation does not restore enzyme activity.

Explanation of 'optimum temperature' as the temperature at which the enzyme reaction rate is highest.

Each enzyme has a different optimal temperature depending on its function and environment.

Introduction to pH and its effect on enzyme activity.

If pH is too high or low, it can decrease the rate of reaction due to changes in the enzyme’s structure.

Like with temperature, pH can cause denaturation by breaking the bonds in the enzyme.

Enzyme activity slows when the active site changes slightly due to pH but can still bind to substrates.

Enzyme optimal pH varies depending on the environment, with most body enzymes working best at neutral pH (around 7), while stomach enzymes work best in acidic conditions (around pH 2).