Chapter 2The Chemistry of Life

Section 2 – 4Chemical Reactions & Enzymes

STAAR STANDARDS

• 9C IDENTIFY AND INVESTIGATE THE ROLE OF ENZYMES

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Enzymes

WHAT ARE THEY?

WHY DO WE NEED THEM?

NAME SOME EXAMPLES?

EnzymesPROTEINS THAT CATALYSE CHEMICAL REACTIONS IN LIVING ORGANISMS

PROPERTIES

SPECIFIC

INCREASE RATE OF THE REACTION

UNCHANGED AT THE END OF THE REACTION

NEED THEMBECAUSE REACTIONS ARE TOO SLOW TO MAINTAIN LIFE

CAN’T INCREASE TEMPERATURES/PRESSURE IN CELLS (FATAL)

Chemical Reaction

KEY CONCEPT: CHEMICAL REACTIONS ALWAYS INVOLVE

BREAKING BONDS OF REACTANTS AND THE FORMATION OF NEW BONDS TO FORM IN PRODUCTS

__________ __________ARROW READS AS “CHANGES TO” OR “FORMS”

REACTANTS PRODUCTS

PRODUCTSUBSTRATE

CHEMICAL REACTIONS

CHEMICAL REACTIONS TAKE PLACE IN CELLS _____________.

ENZYME

CATALYST

ALL THE TIME

Many enzyme NAMES end in _____and the beginning of the name tells what it doesDNA POLYMERASE= “polymerizes” or joins monomers to make DNAPROTEASE= breaks down proteinsATP SYNTHASE= synthesizes ATP

-ASE

Transport of CO2

TISSUE TO BLOODTISSUE TO BLOOD

BLOOD TO LUNGBLOOD TO LUNG

Carbonic anhydraseCO2 + H20 H2CO3

CO2 + H20H2CO3Carbonic anhydrase

YOU BREATHE OUT

Transport of CO2

• WITHOUT carbonic anhydrase the reaction that produces carbonic acid is _____________; only about _______ molecules of carbonic acid are produced in _____________.

• This rate is ______fast enough for your blood to carry away the carbon dioxide released by million of cells.

VERY SLOW2000

ONE HOURNOT

• WITH carbonic anhydrase about __________________ molecules of carbonic acid can be produced every __________.

• The enzyme increases the reaction rate about 10 ___________ times enabling your body to eliminate carbon dioxide efficiently. 11

600,000

SECOND

MILLION

Transport of CO2

Your cells are always making __________ chemicals. They can die if these chemicals are not changed into ________ substances.

CATALASE

HYDROGEN PEROXIDE 2H2O2

WATER + OXYGEN H20 O2

POISONOU

S HARMLESS

ENERGY IN REACTIONS

Key Concept:• Reactions That Release Energy

Often occur spontaneously• Chemical Reactions That Absorb

Energy Will Not Occur Without A Source Of Energy

ENERGY FOR LIFE PROCESSES

_________IS THE ABILITY TO MOVE OR CHANGE MATTER

ENERGY

ENERGY IN REACTIONS

• ENERGY IS ___________ OR _________ EVERY TIME CHEMICAL BONDS FORM OR BREAK.

_________CHANGES DETERMINE WHETHER A REACTION WILL TAKE PLACE OR NOT.

RELEASEDSTORED

ENERGY

METABOLISM IS…..• ________ of all the chemical

reactions in an organism• ALL REACTIONS REQUIRE ______• ___________ IS THE ULTIMATE

ENERGY FOR LIFE ON EARTH

REVIEW

SUM

ENERGYSUNLIGH

T

• ANY PROCESS IN AN ORGANISM THAT INVOLVES __________________ SUBSTANCES FROM SIMPLER SUBSTANCES ____________ ENERGY IN THE PROCESS

REVIEW

ANABOLISM IS…..

PLANTS OBTAIN THEIR ENERGY DIRECTLY FROM SUNLIGHT IN A PROCESS KNOWN AS ___________________

“PHOTO” MEANS-_________________

SYNTHESIS-______________________

SYNTHESIZING

PHOTOSYNTHESIS

LIGHT

TO BUILD OR MAKE

STORING

• THE _____________OF COMPLEX SUBSTANCES INTO SIMPLER ONES, WHICH RESULTS IN THE ___________ OF ENERGY.

REVIEW

CATABOLISM IS…..

LIVING THINGS PRACTICE ANABOLISM AND CATABOLISM AT THE __________ TIME _______ THE TIME.

BREAKDOWN

RELEASE

SAME ALL

EnzymesKey Concept: Cells Use Enzymes To Speed Up

Chemical Reactions That Take Place In Cells– Often act as Catalyst

• Speed up the rate of reaction– Lower activation energy

Chemical reactions need help to get started.

Ex: A fire needs a match to get it started.

______________ to get a chemical reaction _______________

= ________________________ACTIVATION ENERGY

REACTANTSPRODUCTS

ACTIVATIONENERGY

ENERGY REQUIRED

STARTED

IT’S LIKE PUSHING A ROCK UP A HILL

ONCE IT GETS TO TOP . . . IT CAN ROLL BACK ALL BY ITSELF

___________ help chemical reactions _________Catalysts work by ____________ the___________________________to get a chemical reaction started.

DECREASING

CATALYSTS

ACTIVATION ENERGY REQUIRED

HAPPEN FASTER

CATALYSTS in Living Things

In living systems __________ that________________to control chemical reactions are called = _________

PROTEINSACT AS CATALYSTS

ENZYMES

EnzymesEnzymes

FreeEnergy

Progress of the reaction

Reactants

Products

Free energy of activationFree energy of activation

There are thousands of different enzymes in your body.

Why are there so many different enzymes?

Each enzyme has its own unique protein structure and shape, which is designed to match or COMPLEMENT its substrate.

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ENZYMES _____ like a _______________

to only _________of _________.

Enzymes are ___________ by thereaction and ___________

LOCK AND KEY

REUSABLEUNCHANGED

FIT

ONE KIND SUBSTRATE

• THE _______________HYPOTHESIS STATES THAT THE ACTIVE SITE SPECIFICALLY MATCHES THE ___________OF THE SUBSTRATE MOLECULE

enzyme

EACH ENZYME IS SPECIFIC TO ONE SUBSTRATE MOLECULE OR TYPE OF MOLECULE

active site

LOCK AND KEY

SHAPE

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ENZYMES AND SUBSTRATE ARE “MADE” FOR EACH OTHER

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Induced FitInduced Fit• A change in the shapeshape of an enzyme’s active site

• Induced Induced by the substrate

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Enzyme Action: Induced Fit Model

E + S ES complex E + P

S

P

P

SS

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__________ & ______________Conditions that are TOO ACIDIC

or TOO HOT cause proteins to________ or _________

pH TEMPERATURE

UNWIND

FACTORS THAT AFFECT ENZYME ACTIVITY

DENATURE

Regulation of Enzyme Activity

• Most Enzymes work best at pH

~6-8 • Most Enzymes work best at ~37°C which is the normal temperature of the human

body (98.5 F).

• ENZYMES PREFER TO WORK AT AN OPTIMUM pH. OUTSIDE OF ITS pH RANGE THE ENZYME IS DENATURED.

RateOf Reaction

pH

1 2 3 4 5 6 7 8 9 10 11 12

pepsin amylase

THE ACTIVITY AND SHAPE OF ENZYMES IS ALSO AFFECTED BY PH

Optimum pH

Movie

EFFECT OF PH ON ENZYMES

When the pH changes outwith optimal conditions, the shape of the active site of the enzyme alters and the enzyme is denatured.

RateOf Reaction

Temperature/oC0 10 20 30 40 50 60 70

Optimum temperature

Enzyme is denaturing

RATE OF REACTION OF AN ENZYME REACTION CHANGES AT DIFFERENT TEMPERATURES

Molecules gain kinetic energy

AT _____ TEMPERATURES ENZYME CONTROLLED REACTIONS GO __________.

THE RATE OF AN ENZYME CONTROLLED REACTION IS AFFECTED BY TEMPERATURE

LOW

SLOWLY

But this only occurs up to the optimum temperature (usually about 40oC)

The temperature at which the rate of reaction is fastest is known as the optimum temperature

WHEN TEMPERATURE INCREASES THE REACTION ALSO INCREASES

THE ENZYME CHANGES _________AND THE ACTIVE SITE NO LONGER MATCHES THE SHAPE OF THE ________________ MOLECULE

AFTER THE OPTIMUM TEMPERATURE THE HEAT CAUSES THE ENZYME TO DENATURE

SHAPE

SUBSTRATE

Denaturing _______ the _______ of the ______________ so enzyme ______________ to ____________

_______________ (keeping pH and temperature constant) is ______________ for maintaining ____________________

HOMEOSTASIS

CHANGES SHAPEACTIVE SITE

CAN’T BIND SUBSTRATE

IMPORTANTENZYME FUNCTION

YOUR CONNECTIONS

• FEVER IS A RESPONSE TO AN _________________

• HIGH FEVER IS DANGEROUS BECAUSE IT WILL ____________ ENZYMES NECESSARY FOR LIFE

• FEVER EXCEEDING _________CAN BE _________

INACTIVATE

INFECTION

105°FATAL

ENZYMES ARE USED IN THE FOOD INDUSTRY

• _________ BREAK DOWN SUBSTANCES IN APPLE CELL WALLS AND ENABLE GREATER JUICE EXTRACTION.

________ BREAKS DOWN LACTOSE IN MILK INTO ___________ AND ________________. THIS MAKES MILK DRINKABLE FOR LACTOSE INTOLERANT PEOPLE.

PECTINASE

LIPASEGLUCOSEGALACTOSE

ENZYMES ARE USED IN LAUNDRY SOAP

___________ BREAKS DOWN PROTEINS

_________ BREAKS DOWN LIPIDS__________ BREAKS DOWN CARBOHYDRATES

PROTEASE

LIPASE

AMYLASETHESE ENZYMES ALLOW YOU TO WASH CLOTHES AT A LOWER TEMPERATURES…THUS SAVING ENERGY

ENZYMES ARE USED IN SEED GERMINATION

STARCH

embryo plant

AMYLASESECRETED

MALTOSE

ABSORBED

SUBSTRATE

ENZYME-SUBSTRATE COMPLEX

PRODUCTSENZYMEUnchanged& Reusable

ENZYME

REVIEW

?????????????1 2

3

4

5

?????????????

????????????

??????????????????????????

HYDROLYSIS

An Example

SUCROSE + H2O

GLUCOSE + FRUCTOSE

DEHYDRATION SYNTHESIS OR HYDROLYSIS?

An Example

SUCROSE + H2O

GLUCOSE + FRUCTOSE

SUBSTRATES

PRODUCTS

SUBSTRATES OR PRODUCTS?

SUBSTRATES OR PRODUCTS?

SUCRASE

DISACCHARIDE

MONOSACCHARIDE

ENZYME NAME?

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AMINO ACIDS MAKE PROTEINS

ATP

Enzyme Substrate Product(s) Hydrolysis or synthesis?

Amylase Starch Maltose Hydrolysis

Catalase Hydrogen peroxide

Oxygen and water

Hydrolysis

Protease Protein Amino acids Hydrolysis

DNA polymerase

DNA nucleotide Synthesis

Lipase Lipid Glycerol & fatty acids

Hydrolysis

ENZYME SUMMARY

Animation for enzymes• http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapt

er2/animation__how_enzymes_work.html