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Enzymes

We couldnt live with out them!

7/27/2019 Enzymes Structure and Purpose

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What is an enzyme?

Known as a BIOLOGICAL CATALYST

Catalyst is something that speeds up a

chemical reaction

Biological catalyst speeds up reactions in

living cells

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Activation Energy

Do this by lowering the ACTIVATIONENERGY - the energy required for areaction to begin

Progress of reaction

E

nergy

Uncatalysed reaction

Catalysed reaction

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Properties of Enzymes

They are made ofPROTEIN

They are not changed by the reactions

they speed up They are SPECIFIC- means that only one

particular enzyme will work with one

particular substrate

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Other terms you need to know

Substrate the substance that the

enzyme works on e.g.Amylase the

substrate is starch

Product the substance that is made by

the reaction e.g. Breakdown of starch by

Amylase the product is Maltose

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CATALASE

Found in animal and plant cells

Needed to speed up the breakdown of

HYDROGEN PEROXIDE

Breaks it down to OXYGEN and WATER

The word equation for this looks like this

HYDROGEN PEROXIDE

CATALASE

OXYGEN AND WATER

HPCOW

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Amylase

Found in saliva and in the pancreas

Break down enzyme

Breaks STARCH down to MALTOSE

Word equation looks like this

STARCH MALTOSE

AMYLASESAM

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Potato Phosphorylase

Synthesis enzyme (builds up)

Builds Glucose-1-Phosphate moleculesinto Starch

The formation of starch is tested usingiodine solution

Phosphorylase

G1PPS

Glucose-1-Phosphate Starch

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More about Specific

This means amylase will only breakdownstarch

Catalase will only breakdown hydrogen

peroxide

Amylase will NOT breakdown hydrogen

peroxide

Catalase will NOT breakdown starch

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Lock and Key

All enzymes have a special shaped areathat fits onto their substrate

This area is called the ACTIVE SITE

This Active site will fit onto the substrate

while the reaction takes place

Because it fits like a lock and key we call

this the lock and key mechanism

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Model of Lock and Key

productssubstrate

enzyme enzyme unchangedactive site

enzyme substrate complex

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Effect of Temperature

Speed of reaction increases until anOptimum temperature is reached

Optimum temperature is the temperature

at which the enzyme works best

After this point the rate of reaction

decreases until there is no reaction At this point enzyme is said to be

DENATURED active site destroyed

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Effect of pH

Most enzymes have an optimum pH of 7

Some enzymes have a different optimum

pH for example pepsin has an optimum pHof 2