TOPIC 2.5 - ENZYMES

2.5 – A - Enzymes

Understandings

U1: Enzymes have an active site to which specific substrates bind.

Key Terms

Enzyme

Active Site

IB BIO – 2.5 Enzymes are proteins that speed up specific chemical reactions

(anabolic or catabolic). Each enzyme has an active site that allows it

to bind to a specific substrate.

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https://upload.wikimedia.org/wikipedia/commons/9/9f/Lock_and_key.png

Understandings

U2: Enzyme catalysis involves molecular motion and the collision of substrates with the active site.

Key Terms

Enzyme

Active Site

IB BIO – 2.5 The structure and chemical properties of an enzyme’s active site is

complementary to the substrate molecule it binds to.

In order to catalyze the reaction, the substrate must collide with the

enzyme’s active site. When this happens, they form the enzyme-

substrate complex.

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Understandings

U2: Enzyme catalysis involves molecular motion and the collision of substrates with the active site.

Key Terms

Enzyme

Active Site

IB BIO – 2.5 After it binds to the active site, the substrate is broken down by the

enzyme. The products are then released into the environment. The

enzyme is unchanged and can then bind to another substrate.

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Understandings

U2: Enzyme catalysis involves molecular motion and the collision of substrates with the active site.

Key Terms

Enzyme

Active Site

IB BIO – 2.5 6The specificity of enzymes is often called the lock-and-key model,

since only one specific substrate can bind to each active site.

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Understandings

U5: Immobilized enzymes are widely used in industry.

Key Terms

Immobilized Enzymes

IB BIO – 2.5 Immobilized enzymes are those

that are attached to a material so

that it stays in place. To fix them

in place, they can be:

• Bound to solid or porous

materials

• Mixed in with a matrix

• Embedded in a soluble

membrane

These enzymes are not changed

in reactions and so can be used

many times when substrates pass

over them

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Understandings

U5: Immobilized enzymes are widely used in industry.

Key Terms

Immobilized Enzymes

IB BIO – 2.5 Immobilized enzyme have been used in carbon capturing. Polluted

air is passed over enzymes, which traps CO2 for storage. This

technology is being used to reduce emissions from factories.

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https://www.sciencenews.org/sites/default/files/main/articles/CO2_full.jpg

Applications

A1: Methods of production of lactose-free milk and its advantages.

Key Terms

Lactase

Lactose-FreeMilk

IB BIO – 2.5 9Immobilized enzymes are also used in producing lactose-free milk.

Lactase is immobilized in alginate beads and then milk is passed

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over. This breaks

lactase into glucose and

galactose monomers.

Since the enzymes are

bound, they do not

wash away and can be

used many times.

Applications

A1: Methods of production of lactose-free milk and its advantages.

Key Terms

Lactase

Lactose-FreeMilk

IB BIO – 2.5 10Because lactose-free milk has more sugar monomers, it tastes

sweeter. Manufacturers use this to sweeten dairy products without

adding extra sugars.

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REVIE

WIB BIO – 2.5 1. Define enzyme.

2. Outline enzyme-substrate specificity.

3. Define immobilized enzymes

4. Descibe the use of enzymes in production of lactose-free

milk.

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2.5 – B – Enzyme Rates

Understandings

U3: Temperature, pH and substrate concentration affect the rate of activity of enzymes.

Key Terms

IB BIO – 2.5 The function of enzyme is to increase the rate of reactions.

However, their ability to to do can be affected by the environment.

Relevant factors include: - Temperature

- pH

- Substrate Concentration

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https://upload.wikimedia.org/wikipedia/commons/thumb/2/24/Induced_fit_diagram.svg

Understandings

U4: Enzymes can be denatured.

Key Terms

Denaturation

IB BIO – 2.5 Like other proteins, enzymes can be denatured when exposed to

conditions that interfere with internal amino acid interactions.

Each enzyme has optimum conditions in which it most effectively

catalyzes reactions. This is usually related to the habitat of an

organism or a cell’s location within the body.

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http://www.che.caltech.edu/groups/fha/media/Fuels_figs/Fuels_fig3.jpg

Understandings

U3: Temperature, pH and substrate concentration affect the rate of activity of enzymes.

Key Terms

IB BIO – 2.5 Enzymes catalyze reactions at an

optimum temperature, which is

typically related to environment.

• High temperatures cause the

enyme to denature, which

quickly decreases activity.

• As temperature falls below the

optimimum, molecular collisons

decrease. This causes the

reaction rate to fall.

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Understandings

U3: Temperature, pH and substrate concentration affect the rate of activity of enzymes.

Key Terms

IB BIO – 2.5 For example, the bacteria shown below each have a different

optimal temperatures for catalyzing the same reaction.

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http://www.che.caltech.edu/groups/fha/media/Fuels_figs/Fuels_fig3.jpg

Understandings

U3: Temperature, pH and substrate concentration affect the rate of activity of enzymes.

Key Terms

pH

IB BIO – 2.5 Enzyme also have an optimal pH. When conditions deviate from it

and become too basic or acidic, the enzyme can denature.

Optimum pH varies widely among enzymes. For example, the

optimum pH of stomach protease can be as low as 1.6.

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http://schoolbag.info/chemistry/mcat_biochemistry/mcat_biochemistry.files/image041.jpg

Understandings

U3: Temperature, pH and substrate concentrationaffect the rate of activity of enzymes.

Key Terms

Substrate Concentration

IB BIO – 2.5 Substrate concentration refers

to the amount of substrate

available to the enzyme’s

active site

• As concentration decreases,

reaction rate decreases.

• As concentration increases,

reaction rate increases.

When all enzyme active

sites are filled, the reaction

is saturated and the reaction

rate plateaus.

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https://upload.wikimedia.org/wikipedia/commons/thumb/0/09/KinEnzymo(en).svg

REVIE

WIB BIO – 2.5 1. Draw a graph showing the effects of the following

factors on enzyme reaction rates:

- Temperature

- pH

- Substrate Concentration

2. On the graphs you drew, add a dotted line showing

the effects of decrease/increasing each factor. Be

sure to label your lines.

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