GCSE Biology - Enzymes - How Temperature and pH Affect Rate of Reaction
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
🌡️ 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
💡Denaturation
💡Optimum Temperature
💡pH
💡Active Site
💡Kinetic Energy
💡Substrate
💡Reaction Rate
💡Optimal pH
💡Catalysis
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).
Transcripts
in this video we're going to look at how
temperature and pH affect the
functioning of enzymes and therefore the
rate of enzyme controlled
reactions let's start with
temperature this graph here shows how
the rate of an enzyme controlled
reaction changes with
temperature as you can see for the first
part of the curve as the temperature
increases so does the rate of
reaction and this is because all of the
particles will have more kinetic energy
and so they're more likely to collide
and have enough energy to react after
about 37° though the rate starts to drop
rapidly this is because the high
temperatures start to break some of the
bonds holding the enzymes together and
so the active site starts to change
shape if it changes shape enough then
the enzyme won't be able to bind to the
substrate and catalyze the reaction
anymore and at that point we say that
the enzyme has been
denatured so in this case the enzyme
would become denatured at around
45° and at that point the damage is
permanent so even if you lower the
temperature back down the enzyme won't
start working
again another important term to know is
the optimum
temperature which is this temperature
here at which the rate of reaction is
highest so in this case that would be
37° all enzymes have an optimal
temperature but different enzymes will
have different optimal
temperatures the other factor that can
affect enzymes is
pH pH is a measure of acidity and as you
can see on this graph here if the pH
gets to high or too low then it will
lower the rate of
reaction just like with temperatures
this is because some of the bonds
holding the enzyme together start to
break and so the active site starts to
change
shape at first it just changes a bit so
the substrate can still fit but less
well than normal this slows down the
rate of reaction but doesn't completely
stop it soon though the active site
changes shape so much that the substrate
can't fit at all and at this point we'd
say that the enzyme has been denatured
the pH at which the enzyme works best is
called its optimal pH and it depends on
where the enzyme normally works for
example most enzymes in our body work
best at neutral phes of around seven
like in this graph but the ones that
work in the stomach for example have an
optimal pH of around two because they
need to be able to function in the
stomach's acidic environment
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