Download - Chapter 4 - Enzymes
ENZYMES
LIVER
catalase
+ H2O2
H2O + O2
ARE ENZYMES IMPORTANT
?!?
IMPORTANCE OF ENZYMES Majority of reactions in living
organisms are enzyme controlled Fatal damage e.g. toxins buildup, food
cannot be absorbed
WHAT ARE ENZYMES?
A biological catalyst which can alter or speed up a chemical reaction, without itself being chemically changed at the end of the reaction.
ENZYME SOURCES BACTERIA
FUNGI
PLANTS ANIMALS
WHAT ARE ENZYMES MADE OF? PROTEIN
all enzymes are made of proteinBUT not all proteins are enzymes
SUBSTRATE SUBSTRATE = substance on
which enzymes act
E.g. starch, proteins, fats etc
CLASSIFICATION According to the chemical reactions
they catalyze.
ENZYMES SUBSTRATEcarbohydratecelluloseproteinlipidsstarch
CARBOHYDRASECELLULASEPROTEASE
LIPASEAMYLASE
CARBOHYDRASECELLULASEPROTEASE
LIPASEAMYLASE
WHY MUST FOOD BE DIGESTED? too large cannot be absorbed by body cells DIGESTION:
Large, insoluble food molecules broken down into small, soluble & diffusible molecules
USES OF ENZYMES BREAKDOWN
e.g.glucose …. Carbon dioxide + water
SYNTHESISe.g. amino acids….proteins
CHARACTERISTICS1. ALTER OR SPEED UP RATE OF
REACTION
CHARACTERISTICS2. VERY POTENT Remain unchanged Can be reused A small amount for
a large amount of chemical reactions
CHARACTERISTICS3. SPECIFICe.g. amylase only act on starche.g. protease only act on protein
CHARACTERISTICS4. REVERSIBLE REACTIONS
A + B C + D
ENZYME ACTIVE SITE = a position on the
enzyme where the substrate binds
HOW DO ENZYMES WORK?
THE LOCK AND KEY HYPOTHESIS
HOW DO ENZYMES WORK? SPECIFICITY Due to SHAPE
After substrate fits in,enzyme alters shape slightly
ACTIVE SITE
APPLICATIONS
DETERGENT
FRUIT JUICE
pectinase
PAPAYAPAWPAW
papain
MEAT TENDERIZER
oil spills
FACTORS AFFECTING ENZYME ACTIVITY1. TEMPERATURE
inactive
most active
denaturedEn
zym
e a
cti
vit
y
Temperature
OPTIMUM TEMPERATURE
DENATURATION
Shape changed 3D structure lost ACTIVE SITE altered
IRREVERSIBLE DESTRUCTION: extreme heat
High temperature, acids & alkalis
FACTORS AFFECTING ENZYME ACTIVITY2. pH most
active
denaturedOPTIMUM pH
En
zym
e a
cti
vit
y
pHdenatured
FACTORS AFFECTING ENZYME ACTIVITY
3. SUBSTRATE & ENZYME CONCENTRATION
En
zym
e a
cti
vit
y
Substrate concentration
X
Y
Enzyme concentration A
Enzyme concentration B
LIMITING FACTOR Directly affects rate of reaction if
quantity is changed
COENZYMES Some enzymes require
coenzymes NON-PROTEIN organic
compounds Most are vitamins (B complex vitamins)
THE END