Temperature (Enzyme Reaction Rates) — Effects & Examples

Temperature and Rate of Reaction

Temperature influences the rate of reaction similarly to pH. At the ideal (optimum) temperature, the chemical reactions will be very quick. These optimum temperatures are maintained through homeostasis.

However, if the temperature is either too high or too low the rate decreases dramatically. Once the temperature is higher than ideal, the enzyme will become denatured and permanently change shape, causing the enzymes and substrates to no longer fit together.

The relationship between temperature and enzyme activity can be thought of similar to how your own body functions.

When it's freezing out, you're probably fairly slow-moving and need warm clothing to function. At room temperature, you are comfortable and can probably do quite a bit of physical activity without sweating. When it's really hot out, you're sweating, and working out probably isn't even an option.

Enzymes work best at an optimum temperature, and so do you.

$$\color{#8925AE}{\text{Vocabulary Review:}}$$

$\color{#8925AE}{\text{Enzyme}}$ : A protein that acts like a catalyst. It speeds up biological reactions but is not used up during the reaction

$\color{#8925AE}{\text{Activation Energy}}$ : Minimum amount of energy needed to begin a chemical reaction

$\color{#8925AE}{\text{Catalyst}}$ : A substance that speeds up reactions but is not used up during the reaction

$\color{#8925AE}{\text{Substrate}}$ : Molecules that a specific enzyme binds to and recognizes. They are transformed during the reaction

What Effect Does Temperature Have on Enzyme Function?

Enzymes are picky molecules. They work within a very specific range of conditions and fall apart (literally) when those conditions are violated.

Temperature is one factor that increases the rate of an enzyme-catalyzed reaction.

Every enzyme has an optimum temperature—the temperature at which they work best. The rate of reaction is greatest at the optimum temperature.

The graph above shows the optimal temperature for a hypothetical enzyme. We can see that a rise in temperature will increase the activity of the enzyme (to a certain degree). Some enzymes work best under cooler conditions or moderate temperatures, while others require high temperatures. Homeostasis helps make sure each temperature is just right.

As with pH, the temperature range for an enzyme's function tends to be narrow.

So, what happens to enzymes outside their optimal temperature range? Why do they stop working?

The shape of an enzyme is fundamental to its ability to work.

So, damaged enzymes are ones whose shapes have been altered in some way. Damaged enzymes no longer have a lock-and-key fit with their active site and substrates, which means they can't catalyze the reaction.

When an enzyme is denatured, it essentially melts and loses its shape. Denaturation can be caused by heat or any deviation from an enzyme's narrow ideal temperature range.

Key Vocabulary:

1. Enzyme
2. Optimum
3. Denature
4. Substrate

(Video) Effect of Temperature and pH on Enzyme Activity

by Ms Cooper's A level Biology

This video gives a great explanation as to how temperature affects enzyme molecules and their rate of reaction.

(Video) How Enzymes Denature

by FuseSchool - Global Education

Ever wonder what happens when enzymes are placed outside of their ideal conditions? Watch this video to see how enzymes break down and reactions slow when ideal conditions are not met.