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 ENERGYcan give off heat

hydrolysis of molecules in your body… Energy of Activation E A barrier is EXTREMELY high - the reaction will occur only if reactantsed:

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

 Enzymes lower the temperature of the activation energy - Energy of Activation E A 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!!

Bromelai n Pineapple has been used as a medicinal plant in several native cultures and bromelain has been known chemically since Bromelain is a digestive enzyme found in the stem and fruit of the pineapple plant DURKEE meat tenderizer has BROMELAIN

Papai n 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

It ’ s active site

The substrate enters the ezyme ’ s active site

Enzyme  Enzymes are specific to the molecule with which they attach (substrate) molecule it attaches with

Stages of an enzyme-catalyzed- reaction: catalaseH2O2H2O2

Stages of an enzyme-catalyzed- reaction: catalaseH2O2H2O2

Stages of an enzyme-catalyzed- reaction:

catalase H2OH2O O2O2

Energy released

 Enzymes are affected by environmental factors: Energy of Activation E A 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 bonds in the protein …remember, enzymes are 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… DENATURED Acceptable temperature… PERFECT

Too hot… DENATURED hmmm… WHAT would that do to the active site?

 Enzymes do have optimal temperatures:

heat disrupts bonds in the protein …remember, enzymes are PROTEIN

Sometimes enzymes require nonprotein “ helpers ”CoEnzymes 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

-ist Cattle-ist