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CHAPTER 4:

CHEMICAL COMPOSITION

OF THE CELL

Prepared By: Miss Fatimah SaniUNIMAS Biotechnology Resources

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INTRODUCTION

The sum of all chemical reactions within a living

organism is known as metabolism

Metabolic pathways - series of chemicalreactions in which the product of one reaction

is the substrate for the next reaction. The chemical reactions are catalyzed by

enzymes, so the metabolic pathways present inan organism depend on the enzymes present in

the organism.

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METABOLISM

ANABOLISM

Simpler substancesare combined to

form more complexmolecules

Require energy

CATABOLISM

Breakdown of morecomplex organicmolecules into

simpler substances

Release energy

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ENZYMES(general

characteristics)

Proteins

Biologicalcatalysts

Needed insmall

amounts

Notchanged or

destroyed

Highlyspecific

Requirecofactors

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ENZYMES Enzymes are __________ which ______ the rate of

biochemical reactions in the body.

Highly ______.

Catalyze only a single reaction or one kind ofsubstrate

Specific site (______- which only bind to specificsubstrate)

Can be inhibited by ______

Require cofactors to function

Needed in minute amounts

Enzyme names usually end in ase (eg: lactase)

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Enzymes are biological catalyst which increase therate of biochemical reactions in the body.

Highly specific.

Catalyze only a single reaction or one kind ofsubstrate

Specific site (active site - which only bind tospecific substrate)

Can be inhibited by inhibitors

Require cofactors to function

Needed in minute amounts

Enzyme names usually end in ase (eg: lactase)

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INTRACELLULARENZYME

Produced andretained in

the cell itself

EXTRACELLULARENZYME

Secreted from

the cell

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MECHANISM OF ENZYME REACTION

An enzyme has a cleft

in its surface calledthe active site

In the lock and keytheory, the substrate

(key) fits into theactive site of theenzyme (lock)producing enzyme-

substrate complex

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ENZYME-SUBSTRATE COMPLEX

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ENZYME-SUBSTRATE COMPLEX

The substance

(reactant) anenzyme acts onis the substrate

EnzymeSubstrate Joins

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ENZYME-SUBSTRATE COMPLEX

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ACTIVE SITE A restricted region of an enzyme

molecule which binds to the substrate.

EnzymeSubstrate

ActiveSite

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WHAT AFFECTS ENZYME ACTIVITY?

FactorsEffects to the

enzymeGraph

pH

Optimum pH Fastreaction

Extreme pH(acidic/alkaline) no

reaction

Temperature

Reaction decrease /

slow Increase ( reach

optimum temp.)Beyond the optimum

temperature denatured (irreversible)

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FactorsEffects to the

enzymeGraph

Substrate concentration

Reaction rate increases in

direct proportion to the

substrate concentration

Enzyme concentration

Reaction rate increases in

direct proportion to the

enzyme concentration until

maximum rate is achieved

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THE USES OF ENZYME IN DAILY LIFE

Type of industry/application

Enzyme used Uses

Food processingEg: meat products

Textile products

Detergentmanufacturing