Factors affecting enzyme activity

Factors affecting enzyme activity

​Describe and explain the effect of temperature changes on enzyme activity.

Multiple Choice

Human digestion involves which type of enzyme?

• Extra-cellular

• Intra-cellular

Multiple Choice

Which of the following is a protease enzyme?

• Catalase

• Trypsin

• Amylase

• Maltase

Multiple Choice

Where is trypsin used?

• The pancreas

• The small intestines

Multiple Choice

Which type of reaction is used to break bonds in biological molecules?

• Hydrolysis

• Condensation

Multiple Choice

Enzymes increase the rate of a reaction by...

• ...increasing the activation energy

• ...decreasing the activation energy

Multiple Choice

Which theory for enzyme action suggests that the active site has a fixed shape?

• Lock and key hypothesis

• Induced fit hypothesis

Multiple Choice

Which type of reaction will be helped by bringing molecules closer together?

• Catabolic

• Anabolic

Multiple Choice

Which part of the amino acids that form the active site are most likely to interact with the substrates atom groups?

• Backbone NCC

• R groups

​Factors affecting enzyme activity

The rate of an enzyme-controlled reaction is affected by:

• Temperature

• pH

• ​Enzyme concentration

• Substrate concentration​

Effect of temperature

​Effect of temperature

To catalyse a reaction, a substrate molecule must collide with an enzymes active site.

​

Increasing the temperature gives molecules more kinetic energy so they move around more quickly. This increases the chances of substrate and active site colliding, increasing the rate of reaction.

​​

​Effect of temperature

​As a general rule, the rate of reaction doubles for each 10^oC rise in temperature until the OPTIMUM temperature is reached- we say it has a temperature coefficient (Q10) of 2​

​

Temperature coefficient = rate of reaction at X + 10^oC

                                              rate of reaction at X ^oC

​

For example, if the rate of reaction at 30^oC is 40, the rate of reaction at 20^oC​ will be 20.

​Effect of temperature

​Above the optimum temperature, the increasing vibration of the molecules causes hydrogen and ionic bonds to break and this in turn causes a change in the tertiary structure of the enzyme. This alters the shape of the active site of the enzyme.

​

​The enzyme is DENATURED - this is a permanent change in the structure .

​Effect of temperature

​Note, at low temperatures, the enzyme is INACTIVATED as the molecules have less kinetic energy. However, the enzyme can work again if the temperature is raised!

Multiple Choice

Increasing the temperature gives enzyme and substrate molecules ____ kinetic energy

• more

• less

Multiple Choice

The temperature that an enzyme works best is known as it's...

• ...ultimate temperature

• ...optimum temperature

• ...favoured temperature

• ...peak temperature

Multiple Choice

At what temperature do enzymes work best?

• 37^oC

• 40^oC

• It depends on the enzyme

• Anything less than 40^oC

Multiple Choice

At low temperatures, enzymes are...

• ...denatured

• ...inactivated

Multiple Choice

At high temperatures, enzymes denature as the ________ structure is altered

• primary

• secondary

• tertiary

Multiple Choice

Denaturation of enzymes is...

• ...reversible

• ...irreversible

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Enzymes act as biological...

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They are soluble due to them being

proteins

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Enzymes have an _______ _______ with a specific shape that matches its substrate

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Enzymes catalyse both anabolic and

reactions

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Amylase breaks down starch into

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Enzymes lower the _______ ______ of a reaction, allowing it to proceed at a lower temperature than it normally would.

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Enzymes can only increase the rates of reaction up to a certain point called the

.

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The enzyme molecule and the substance it acts on fit together very precisely, giving rise to the ____ ___ ____ theory of enzyme action.

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In practice, the enzyme is thought to change shape slightly and so mould itself to the shape of the substance it acts on. This is called the ______ ___ theory of enzyme action.