Unit 5 1/2

A chemical reaction will occur spontaneously…

but the process may be too slow to be effective, in living cells…

A chemical reaction will occur spontaneously, but the process may be too slow to be effective, in living cells…

ex. hydrolysis of sucrose:

adding water~ they break apart

ex. hydrolysis of sucrose:

energy is required to break the bond between those two carbohydrate molecules,

ex. hydrolysis of sucrose:

+ adding water~ they break apart

Chemical reactions can’t “get started” w/o energy being added

• In other words… ENERGY must be added in order for the reaction to start…

• Kinda like you cannot put keys on a ring… without opening the ring first!

ex. hydrolysis of sucrose:

energy required to break bonds = Activation Energy

it is EXTREMELY HIGH!

ex. hydrolysis of sucrose:

Activation energy!!

ex. hydrolysis of sucrose:

Activation Energy - -

the reaction can occur only when energy is added:

ACTIVATION ENERGY can give off heat

hydrolysis of molecules in your body…

Energy of Activation EA barrier is EXTREMELY high - the reaction will occur only if reactantsed:

Energy of Activation EA barrier is EXTREMELY high - the reaction will occur only if reactants are heated:

Enzymes lower the temperature of the

activation energy -Energy of Activation EA

barrier is EXTREMELY

high - the reaction will occur only if reactants are

heated:

Enzymes lower activation energy so rxn. can occur -

Too hot!!!

AHHHHH!!!

Enzymes lower activation energy this allows chemical reactions to

happen in your body FASTER!!

Bromelain

Pineapple has been used as a medicinal plant in several native cultures and bromelain has been known chemically since 1876.

Bromelain is a digestive enzyme found in the stem and fruit of the pineapple plant

DURKEE meat tenderizer has BROMELAIN

Papain

Its utility is in breaking down the tough meat fibers and has been utilized for thousands of years in its native South America.

It is sold as a component in powdered meat tenderizer available in most supermarkets.

The cheap meat tenderizer had PAPAIN

This is an enzyme called CATALASE

This is an enzyme called CATALASE

It’s active siteIt’s active site

The substrate enters the ezyme’s active site

The substrate enters the ezyme’s active site

EnzymeEnzyme

Enzymes are specific to the molecule with which they attach (substrate)

molecule it attaches molecule it attaches withwith

Stages of an enzyme-catalyzed-reaction:

catalase H2O2

Stages of an enzyme-catalyzed-reaction:

catalase H2O2

Stages of an enzyme-catalyzed-reaction:

Stages of an enzyme-catalyzed-reaction:

catalaseH2O

O2

Energy Energy releasedreleased

Energy Energy releasedreleased

Energy Energy releasedreleased

Energy Energy releasedreleased

Enzymes are affected by environmental factors:

Energy of Activation EA barrier is EXTREMELY high - the reaction will occur only if reactants are heated:

ex. pH

Beyond that temp, speed of reaction drops:

Enzymes do have optimal pH:

Improper pH disrupts Improper pH disrupts bonds in the protein bonds in the protein

……remember, enzymes remember, enzymes are PROTEINare PROTEIN

Enzymes are affected by environmental factors:

ex. temperature

Enzymes are affected by environmental factors:ex. too cold

Enzymes slow down

They cannot “hit” as many substrates

Enzymes are affected by environmental factors:

ex. amount of heat

Too hot… Too hot… DENATUREDDENATURED

Acceptable Acceptable temperature…temperature…

PERFECTPERFECT

Too hot… Too hot… DENATUREDDENATURED

hmmm… hmmm… WHATWHAT would would that do to the that do to the activeactive site?site?

Enzymes do have optimal temperatures:

heatheat disrupts bonds in disrupts bonds in the protein the protein

……remember, enzymes remember, enzymes are PROTEINare PROTEIN

Sometimes enzymes require nonprotein “helpers”

CoEnzymesCoEnzymes

Molecules that are bound to the active site

“A cell is not just a bag of chemicals with

thousands of different kinds of enzymes and substrates wandering

about randomly.”

Control of metabolism-

Chaos would result if all of a cell’s metabolic pathways were open at the same time… chemical reactions must be regulated

Cattle-ist-ist