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• Look at the key words

• How many seem familiar?

• Turn it over and now look at the definitions

• How many words could you match up from memory?

• Now using the definitions and table, jot down the word and definition

(why not number them and write them up for consolidation)

1.7 Enzyme action

Recap:

• Primary• Secondary• Tertiary• Quaternary

• Levels of protein structure, what happens at each, what kind of bonding, additional info, examples etc 5 mins

LO:

• How do enzymes speed up chemical reactions?

• How does the structure of enzyme molecules relate to their function?

• What is the lock and key model of enzyme action?

Primary structure to tertiary structure in enzymes

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Week 18

Enzymes the biological catalysts:

• Enzymes are globular proteins.• Enzymes are catalysts.• Catalysts speed up chemical

reactions without undergoing permanent changes.

• Enzymes/catalysts are not used up in chemical reactions and can therefore be reused repeatedly.

Enzymes lower the activation energy:

• For the reaction to take place a number of things must happen.

• 1st the sucrose & water must collide with sufficient energy to form glucose & fructose.

• The energy of the products must be less than that of the substrates.

• An initial boost of energy is needed to start the reaction- the activation energy.

Sucrose + water glucose + fructose

Activation Energy:• An energy barrier

that must be overcome before the reaction can proceed.

• Enzymes lower the activation energy.

• The reactions will occur at a lower temperature.

• With out enzymes 37oC would be to cold for reactions to proceed at a fast enough rate to support life.

Reactants = substrate

Activation energy (maltose to glucose)

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How the enzyme maltase lowers the activation energy needed to convert

maltose to glucose (no boiling in acid required!)

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Enzyme substrate complex:

• The active site forms a small hollow depression within the enzyme molecule.

• The molecule on which the enzyme acts is called the substrate.

• The substrate is a complementary shape to the active site

• The two fit to form the enzyme- substrate complex.

• Temporary bonds form between the amino acids of the active site and groups on the substrate molecule.

Key vocab

The lock-and-key hypothesis – we don’t think this is how it works anymore due to increasing scientific evidence about binding to other areas of

the enzyme leading to decreased activity – suggests it would have changed the shape

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Week 18

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Induced fit model: Like a hand fitting into a glove (enzyme) – it ‘moulds’ around the hand (substrate)

Tasks:Exam questionsQuestions to complete•Why is the induced fit a better model than the lock and key theory?•Are all proteins enzymes?•Do all proteins have an active site?•Do all molecules have active sites, or other sites?Enzymes dominoes Key words and definitions activity.

A metabolic pathway

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Week 18

Mould produces extracellular enzymes to digest bread

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Lysosome and phagocytosis

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Phenylketonuria sequence and effects

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Week 18