2.5 Enzymes

Enzymes control the metabolism of the cell.

C1.1 Enzymes

Essential Idea

Understandings

C1.1 Enzymes

Understandings

Syllabus Reference

https://quizlet.com/_8xte0y?x=1jqt&i=28b19k

C1.1 Enzymes

Vocabulary

1. Draw a glycerol and 3 fatty acids
2. Circle and name the type of reaction
3. Draw 2 amino acids
4. Circle and name the type of reaction
5. Draw starch
6. Describe the levels of protein structure

C1.1 Enzymes

Do Now

Ext: What types of fats are there and what are their properties?

How do you draw them?

https://www.youtube.com/watch?v=rlH1ym916Fo

C1.1 Enzymes

Draw what your partner describes to you.

C1.1.4—Enzymes as globular proteins with an active site for catalysis

An enzyme is a

biological catalyst

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A globular protein that increases the rate of a biochemical reaction by lowering the activation energy threshold

C1.1 Enzymes

What is an enzyme?

C1.1.1—Enzymes as catalysts

Products

Catalyst

Denatured

Optimal

Collisions

Kinetic

• An enzyme is a biological ________________ made of _________. A ___________ protein that increases the rate of a biochemical reaction by lowering the ____________ __________threshold
• This means it speeds up/slows down reactions. 
• A specific substrate is____________ to the ___________ site of an ____________.
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Enzymes

What is an enzyme?

C1.1.1—Enzymes as catalysts

catalyst

protein

Globular

activation

energy

complementary

active

enzyme

enzyme

active site

substrate

enzyme-substrate complex

enzyme

product

• The enzyme is the same as a _______________ and the substrate acts as a key. The most current model is the __________ fit model, where the enzyme will make __________________ changes to fit the substrate. The enzyme is like a ___________.

Enzymes

What is an enzyme?

C1.1.5—Interactions between substrate and active site to allow induced-fit binding

lock

induced

conformational

glove

Conformational: the shape or structure of something

• If the enzyme’s active site changed shape, the substrate _____________fit into the enzyme. The enzyme has become ____________________. 
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• Enzymes have an ___________________ temperature and pH. As the temperature increases, there are more ____________ due to increased _____________ energy.  

Enzymes

What is an enzyme?

C1.1.5—Interactions between substrate and active site to allow induced-fit binding

Cannot

denatured

optimum

collisions

kinetic

• At ___________ temperatures, there is __________ kinetic energy. Therefore the reaction is limited due to insufficient c__________________ between substrates and _____________ active sites.

• As the temperature increases, there are more ____________ due to increased _____________ energy.

• Enzymes have an o___________________ temperature and pH where the enzyme activity is at its ______________.

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C1.1 Enzymes

What is an enzyme?

C1.1.8—Effects of temperature, pH and substrate concentration on the rate of enzyme activity

low

less

collisions

collisions

enzyme’s

kinetic

optimum

optimal functioning

C1.1 Enzymes

What is denaturation?

C1.1.8—Effects of temperature, pH and substrate concentration on the rate of enzyme activity

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

2.5 Enzymes

Factors affecting the rate of enzyme activity

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

• Ionisation is the process where H+ and OH- ions from acidic and alkaline solutions interact with amino acids and change the tertiary structure of the enzyme.

• Find 5 enzymes in the body and state their optimum pH

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2.5 Enzymes

What is activation energy?

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

Find definitions for these terms:

Catalyst:

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Specificity:

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Substrate:

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Product:

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A substance that speeds up reactions without changing the produced substances

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Only able to catalyse specific reactions

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The molecule(s) the enzyme works on (reactant in a biochemical reaction)

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Molecule(s) produced by enzymes

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2.5 Enzymes

What is the definition for the following?

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

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When a substrate fits into the active site an enzyme-substrate complex is formed

The enzyme catalyses the conversion of the substrate into a product (or products), and an enzyme-product complex is formed

The products leave the active site and the enzyme is able to work on the next substrate molecule

2.5 Enzymes

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

Active Site

The site on the surface of an enzyme which binds to the substrate molecule.

2.5 Enzymes

What is the active Site?

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

Polar regions of amino acids attract substrate and active site of the enzyme

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

Your aim is to be able not just to recreate the graphs, but to annotate and explain their shape by knowing what is happening at the molecular level.

Pattern Explain Analysis Data

2.5 Enzymes

Factors affecting the rate of enzyme activity

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

Lock and Key Mechanism

The active site and substrate are complementary to each other in terms of both shape and chemical properties (e.g. opposite charges)

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Enzyme and substrate fit together like a lock and key

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2.5 Enzymes

Lock and Key Model

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

The requirements for an effective collision (for a chemical reaction to occur):

1. The reactants must collide with each other.
2. The molecules must have sufficient energy to initiate the reaction (called activation energy).
3. The molecules must have the proper orientation.

2.5 Enzymes

What is collision theory?

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

Catalase

Catalyses the breakdown of hydrogen peroxide (metabolic poison) into oxygen and water

2.5 Enzymes

What is catalase?

Review

Enzymes

Explain the effects of temperature

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

2.5 Enzymes

Explain the effects of temperature, pH and substrate concentration on enzyme activity

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

(a) As the substrate concentration increases the rate of reaction increases.

There are many collisions between the substrate and the enzyme and many enzyme-substrate complexes are formed.

(b) Rate of products formation slows.

The competition of the substrate molecules for active sites is increasing.

(c) The rate is constant.

All active sites are saturated with substrate such that adding more substrate does not increase the rate of reaction.

(a) As temperature increases rate of reaction also increases. Substrate and enzyme molecules have greater kinetic energy leading to more collisions and the formation of more enzyme-substrate complexes.

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(b) The optimum temperature gives the highest rate of reaction.

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(c) High temperatures increase the kinetic energy of the atoms in the enzyme molecule so much that bonds in the active site are broken and, denaturation occurs.

2.5 Enzymes

Explain the effects of temperature, pH and substrate concentration on enzyme activity

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

• At a pH lower than the optimum the concentration of H⁺ ions in the solution is higher than normal.
• H⁺ ions are attracted to electronegative regions of the enzyme protein.
• Bonds are formed or changed as a consequence and this in turn changes the shape of the enzyme molecule and the active site.
• Changes in active site shape reduces the ability of the substrate to bind with the active site.
• pH values above the optimum have a similar effect on the rate of reaction.

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2.5 Enzymes

Explain the effects of temperature, pH and substrate concentration on enzyme activity

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

Effect of pH

optimum

2.5 Enzymes

Explain the effects of temperature, pH and substrate concentration on enzyme activity

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

Effect of temperature

a)

b)

c)

2.5 Enzymes

Explain the effects of temperature, pH and substrate concentration on enzyme activity

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

• Increasing temperature causes the average kinetic energy of the enzyme atoms to increase. Atoms in the enzyme molecule vibrate more violently.
• The vibrations break bonds in the tertiary structure of the enzyme.
• The weakest bonds break first, in this case the hydrogen bonds.
• This changes the shape of the active site, which prevents the substrate from binding.
• The rate of reaction reduces or stops.

2.5 Enzymes

Explain the effects of temperature, pH and substrate concentration on enzyme activity

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

Denaturation

A structural change in a protein that results in the loss of its biological properties.

2.5 Enzymes

Explain the effects of temperature

2.5.U4 Enzymes can be denatured.

How are proteins denatured?

2.5 Enzymes

Explain the effects of temperature

2.5.U4 Enzymes can be denatured.

Design of a controlled experiment to investigate temperature or pH.

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1. Choose either catalase, pepsin, pectinase, rennin, lipase, amylase or protease and one of the factors listed above.
2. State the substrate and products
3. List how and what you would measure (dependent variable)
4. Suggest ways to make your experiment accurate (controlled variables)and reliable (repeated and reproducible).
5. Propose a hypothesis of what you would expect
6. List what results you would obtain and what you could do with these

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2.5 Enzymes

Explain the effects of temperature or pH

2.5S1 Design of experiments to test the effect of temperature, pH and substrate concentration on the activity of enzymes.

2.5 Enzymes

Explain the effects of temperature or pH

Skill: Design of experiments to test the effect of temperature, pH and substrate concentration on the activity of enzymes.

2.5 Enzymes

Explain the effects of temperature or pH

Skill: Design of experiments to test the effect of temperature, pH and substrate concentration on the activity of enzymes.

2.5.U5 Immobilized enzymes are widely used in industry.

Common uses of enzymes in industry include:

2.5 Enzymes

Common uses of enzymes in industry include:

2.5.U5 Immobilized enzymes are widely used in industry.

Enzymes are widely used in the food industry, e.g.

• fruit juice, pectinase to increase the juice yield from fruit
• Fructose is used as a sweetener, it is converted from glucose by isomerase
• Rennin is used to help in cheese production

2.5 Enzymes

Common uses of enzymes in industry include:

2.5.U5 Immobilized enzymes are widely used in industry.

In Medicine & Biotechnology enzymes are widely used in everything from diagnostic tests to contact lens cleaners to cutting DNA in genetic engineering.

2.5 Enzymes

Common uses of enzymes in industry include:

2.5.U5 Immobilized enzymes are widely used in industry.

In the brewing industry enzymes help a number of processes including the clarification of the beer

2.5 Enzymes

Common uses of enzymes in industry include:

2.5.U5 Immobilized enzymes are widely used in industry.

Detergents contain proteases and lipases to help breakdown protein and fat stains

2.5 Enzymes

Common uses of enzymes in industry include:

2.5.U5 Immobilized enzymes are widely used in industry.

2.5.U5 Immobilized enzymes are widely used in industry.

• Concentration of substrate can be increased as the enzyme is not dissolved – this increases the rate of reaction
• Recycled enzymes can be used many times, immobilized enzymes are easy to separate from the reaction mixture, resulting in a cost saving.
• Separation of the products is straight forward (this also means that the reaction can stopped at the correct time).
• Stability of the enzyme to changes in temperature and pH is increased reducing the rate of degradation, again resulting in a cost saving.

Enzymes used in industry are usually immobilized. They are attached to a material so that their movement is restricted. Common ways of doing this are:

• Aggregations of enzymes bonded together
• Attached to surfaces, e.g. glass
• Entrapped in gels, e.g. alginate gel beads

2.5 Enzymes

Advantages of enzyme immobilization extra information:

2.5.U5 Immobilized enzymes are widely used in industry.

Lactose intolerance and human evolution

2.5 Enzymes

Guiding Questions

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

• What is lactose intolerance?

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• How can immobilised enzymes be used to remove lactose from milk?

https://www.youtube.com/watch?v=MA9boI1qTuk

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2.5 Enzymes

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

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

Production of Lactose-free milk

• Lactase obtained from commonly from yeast
• Lactase is bound to the surface of alginate beads
• Milk is passed (repeatedly) over the beads
• The lactose is broken down into glucose and galactose
• The immobilized enzyme remains to be used again and does not affect the quality of the lactose free milk

Production of lactose-free milk

2.5 Enzymes

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

Other uses of lactose free milk:

• As a means to increase the sweetness of milk (glucose and galactose are sweeter in flavour), thus negating the need for artificial sweeteners
• As a way of reducing the crystallisation of ice-creams (glucose and galactose are more soluble than lactose)
• As a means of shortening the production time for yogurts or cheese (bacteria ferment glucose and galactose more readily than lactose)

Production of lactose-free milk

2.5 Enzymes

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

Lactose Intolerance

Lactose is a disaccharide of glucose and galactose which can be broken down by the enzyme lactase.

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Mammals exhibit a marked decrease in lactase production after weaning, leading to lactose intolerance

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Incidence is particularly high in Asian / African / Native American / Aboriginal populations.

Lactose intolerance

2.5 Enzymes

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

Review

Review

2.5 Enzymes

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

1. Mix 4ml of amylase with 6ml of sodium alginate and stir well for 2 minutes
2. Using a pipette drop the mixture into 50ml of calcium chloride solution.
3. Sieve the beads and rinse with water
4. Put a 1cm square of muslin in the bottom of the syringe
5. Add a tube and a clamp to control the flow of starch.
6. Run the starch into the column 3 to 5 times.
7. Run out some product and test for glucose (Benedict’s)each time

Modelling Immobilisation of Amylase

2.5 Enzymes

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

• 2.5 Enzyme Quiz

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2.5 Enzymes

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• 2.5 Enzymes Kahoot

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2.5 Enzymes

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