Enzymes

B3a

OBJECTVES

Key Objective• Describe the factor affecting the function of enzymes

• State the function of enzymes (D)• Describe how changing temperature and pH will change

the rate of reaction of an enzyme-catalysed reaction (C)• Explain the specificity of enzymes in terms of the ‘lock and

key’ mechanism (B)• Explain how enzyme activity is affected by pH and

temperature (A)• Link the effect of temperature and pH on the active site to

the enzyme’s ability to function (A*)

STARTER

• What are enzymes?• What is their function?• Give an example of a specific enzyme.• What happens to the rate of an enzyme-

catalysed reaction as temperature increases?• What is the name of the model used to describe

how enzymes work?• What happens to enzymes as temperature or pH

increases?• What effect does this have on the reaction?• Why?

STARTER• What are enzymes?

– Proteins or biological catalysts• What is their function?

– To speed up the rate of a chemical reaction• Give an example of a specific enzyme.

– Carbohydrase, Lipase, Protease, Catalase• What happens to the rate of an enzyme- catalysed reaction as

temperature increases?– Rises to a peak and then drops rapidly

• What is the name of the model used to describe how enzymes work?– Lock & Key theory

• What happens to enzymes as temperature or pH increases?– Denature (twist out of shape)

• What effect does this have on the reaction?– Reaction slows then stops or stops immediately

• Why?– Substrates no longer fit into the active site

How did you do?1-2 marks = D3-4 marks = C5 marks = B6-7 marks = A8 marks = A*

Why do we need to break down food?

Digestive system Blood

Digestive enzymes are the chemicals that break large insoluble food molecules into smaller soluble molecules.

Digestive enzymes are classified by the type of food that they affect, so there are three main types:

Different types of digestive enzymes

carbohydrase – breaks carbohydrate into smaller sugars.

protease – breaks protein into amino acids.

lipase – breaks fat into fatty acids and glycerol.

OBJECTVES

Key Objective• Describe the factor affecting the function of enzymes

• State the function of enzymes (D)• Describe how changing temperature and pH will change

the rate of reaction of an enzyme-catalysed reaction (C)• Explain the specificity of enzymes in terms of the ‘lock and

key’ mechanism (B)• Explain how enzyme activity is affected by pH and

temperature (A)• Link the effect of temperature and pH on the active site to

the enzyme’s ability to function (A*)

How enzymes work

The lock and key model

Factors affecting enzyme action

Structure of an enzyme molecule

• Enzymes are proteins made up on long chains of amino acids.

• These long chains fold to produce a special shape which is vital for the enzyme‘s function.

Active Site

OBJECTVES

Key Objective• Describe the factor affecting the function of enzymes

• State the function of enzymes (D)• Describe how changing temperature and pH will change

the rate of reaction of an enzyme-catalysed reaction (C)• Explain the specificity of enzymes in terms of the ‘lock and

key’ mechanism (B)• Explain how enzyme activity is affected by pH and

temperature (A)• Link the effect of temperature and pH on the active site to

the enzyme’s ability to function (A*)

PLENARY

• Draw cartoons (with descriptions) showing how enzymes work and how temperature affects their function.

• Include as much information from the lesson as you think is appropriate. – (Tip: think about the objectives!)

PLENARY

• Draw cartoons (with descriptions) showing how enzymes work and how temperature affects their function.

• Include as much information from the lesson as you think is appropriate. – (Tip: think about the objectives!)

How did you do?Have you…• Stated/shown what enzymes do? (D)• Described how temperature and pH affects the rate of enzyme activity? (C)• Shown that enzymes are specific? (B)• Explained how enzyme activity is affected by temperature? (A)• Explained how the active site is affected by high temperatures and what this means for the enzyme’s ability to work? (A*)