Enzymes (Part I)

Objectives for todayWhat are enzymes? What do they

do?Characteristic of enzymes

Overview Biological Molecules

Water and Living Organisms

Carbohydrates, Fats and Proteins

Enzymes

Lock & Key hypothesis

Mode of Action

Factors affecting enzyme

reactionsSpeed up chemicalRxnNot chemically altered at the endOf Rxn

Lowering Activation Energy

Specificity

Temperature pH

RecapFunctions of food for living

organismCarbohydrates, proteins and

lipidsCondensation and hydrolysis

How can the waffle be quickly broken down into individual glucose, lipid molecule and amino acid to provide you with energy?

Hydrolysis in the LabHowever, in laboratory, hydrolysis of complex food molecules like starch takes a long time and to speed things up, high temperature is needed to chemically break down starch molecules!

Hydrolysis in our BodySo, how is it possible that our body can break down food molecules so fast and break down in a relatively low temperature of 37˚C?

EnzymesEnzymes are biological

catalyst… 1.It has mass2.Most enzymes

are made up of proteins

3.There are thousands of different enzymes in our body each with a unique function!

Catalyst **“Substance which can alter or speed

up a chemical reaction, without itself being chemically changed at the end of the reaction”

1. Speed up chemical reaction2. Without being chemically changed

Crack the seed demonstration!Need 2 volunteersObjective is to crack 10 seeds in

1 minSee who is the faster one!

11

Can we break the glycosidic bonds?Hydrolytic reaction The break up of a disaccharide into monosaccharid is sped up by enzyme

+OH O

H

+Water

ENZYME

1 Maltose2

Glucose

Water

OH

OH

ENZYME

Water

ENZYME

OH

OH

Cut the wire

ScissorsSpeed up the cutting

process!

After cutting, still remain as a

scissors! Not altered!

Enzyme

ENZYMESpeed up the

chemical reaction! Like condensation and hydrolysis

Not chemically altered at the end of

the reaction!

Quick factsSince it is chemically unchanged

at the end of the reaction, enzymes can be used over and over again!

An enzyme which helps to break down starch can produce millions of glucose molecules in ONE second!

The Seed cracker is the catalyst!

1.Speed up chemical reaction

2.Without being chemically changed

3. Lower Activation energy

Reactants = “ You in bed in

home clothes”

6:20am

Products = “ You in school with uniform”

7:29am

Normal Day

Exam!

3. Lower Activation energy

Reactants = “ Starch + Water”

Products = “Glucose

molecules”

Without Enzyme

s

With Enzyme

s!

Activation energyActivation energy is defined as the energy needed to start a chemical reaction.

Since activation is lowered, our body can break down many biomolecules at 37˚C. No need any high temperature heating breakdown like those in labs.

Summary Enzymes

Biological Catalysts

Not chemically altered at the end of the Rxn

Can be reused many times

Speed up chemical reactions

Speed up condensation and hydrolysis

Lower activation energy of chemical Rxn

Some review questionsEnzymes are only found in living

thingsEnzymes cannot be re-used after a

chemical reaction since it has undergone chemical reactions

The activation energy is higher for a enzymatic reaction because enzymes need energy to function

Enzymes can only break things down and not build things up

Going a bit furtherWhere can enzymes be found?Can they be extracted out of the

body and still be functional?Let’s look at something more

close to our lives!

Flies! Do you know how they eat?

HWFind out what is the meaning of G6PD!