IBDP CORE>TOPIC 3.6>ENZYMES
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ASSESSMENT STATEMENT
3.6.1 Define enzyme and active site .
3.6.2 Explain enzyme–substrate specificity.
3.6.3 Explain the effects of temperature, pH and substrate concentration on enzyme activity.
3.6.4 Define denaturation.
3.6.5 Explain the use of lactase in the production of lactose-free milk.
3.6.2 Explain enzyme–substrate specificity.
3.6.3 Explain the effects of temperature, pH and substrate concentration on enzyme activity.
3.6.4 Define denaturation.
3.6.5 Explain the use of lactase in the production of lactose-free milk.
PRACTICAL BASED TEACHING: LEARNING BY INVESTIGATING
DAY 1. 3.6.1 DEFINE ENZYME AND ACTIVE SITE
what is the difference between enzymes and inorganic catalysts?
Experimental evidence…….
Enzymes and catalysts both affect the rate of a reaction. The difference between catalysts and enzymes is that while catalysts are inorganic compounds, enzymes are largely organic in nature and are bio-catalysts. Even though all known enzymes are catalysts, all catalysts are not enzymes.
DAY 2 What are enzymes made up of ? what is the mechanism by which they work?
DAY 3. 3.6.2 Explain enzyme-substrate specificity
Investigation: can any enzyme act on any substrate?
Enzymes have a specific shape; substrate has a specific or complementary shape to the active site of the enzyme. The active site of enzyme binds only to specific substrates. Active site works as a lock and substrate as a key. This the lock and key model.
However the active site of the enzyme is not rigid and substrate can induce slight changes in shape, this allows substrates of similar structure to bind with same enzyme. This is called induced fit. (topic 7.6.2 HL)
However the active site of the enzyme is not rigid and substrate can induce slight changes in shape, this allows substrates of similar structure to bind with same enzyme. This is called induced fit. (topic 7.6.2 HL)
DAY 4. What is activation energy?
Consider a mixture of ethanol and oxygen maintained at room temperature. Although a reaction between the two substances is thermodynamically possible, it does not occur unless energy is supplied to it. This energy is called the activation energy. Thus, activation energy is defined as the energy required to make substances react. It represents the energy barrier that has to be overcome before a reaction can take place to form products.
The greater the activation energy, the slower the reaction at any particular temperature. If the activation energy of a reaction is decreased, the rate of reaction would be increased.
The greater the activation energy, the slower the reaction at any particular temperature. If the activation energy of a reaction is decreased, the rate of reaction would be increased.
DAY 5. 3.6.3 Explain the effects of temperature, pH and substrate concentration on enzyme activity.
DAY 6. Enzymes and substrate concentration
DAY 7. 3.6.4 Denaturation of the enzyme
Denaturation is a structural change in a protein that results in the loss (usually permanent) of its biological properties
- Heat and pH are two agents which may cause denaturation of an enzyme
3.6.5. Use of lactase in lactose free milk
Lactose is a disaccharide of glucose and galactose which can be broken down by the enzyme lactase
Historically, mammals exhibit a marked decrease in lactase production after weaning - leading to lactose intolerance (incidence is particularly high in Asian / African / Native American / Aboriginal populations) Lactose-free milk can be produced by purifying lactase (e.g. from yeast or bacteria) and binding it to an inert substance (such as alginate beads) Milk passed over this immobilised enzyme will become lactose-free The generation of lactose-free milk can be used in a number of ways:
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