ENZYMESACTIVATION ENERGY

&REACTION GRAPHS

ADDITIONAL GRAPHS & PRACTICE PROBLEMS

An enzyme:

• is a protein• is a biologic catalyst• is very specific• is not used up in a chemical reaction• has an active site that its substrate

binds to• lowers the activation energy of a

reaction

Enzymes

Enzymes

Types of Chemical Reactions

ENDERGONIC• REACTIONS IN WHICH

THE ENERGY OF THE PRODUCT(S) IS GREATER THAN THE ENERGY OF THE REACTANTS

• THAT IS: ENERGY HAS BEEN ABSORBED IN THE REACTION

EXERGONIC• REACTIONS IN WHICH

THE ENERGY OF THE REACTANTSIS GREATER THAN ENERGY OF THE PRODUCTS

• THAT IS: ENERGY HAS BEEN RELEASED IN THE REACTION

(don’t worry about ∆G in diagram below)

Endergonic & Exergonic Energy Graphs

What is activation energy?

• It is the nrg necessary to get the reaction to go forward (even if it is an exergonic reaction).

What is activation energy?

Enzymes Lower the Activation Energy so the Reaction occurs faster & requires less energy

• Red line in graph represents how much energy needed to get from reactants products

• Blue line represents how much energy needed when an enzyme is present

Enzymes Lower the Activation Energy so the Reaction occurs faster & requires less energy

• The peak of the red line (or blue line) coincides with the point where the bonds in the reactants of the reaction are weakest. It is also called a transition state

• http://www.youtube.com/watch?v=VbIaK6PLrRM

• http://www.stolaf.edu/people/giannini/flashanimat/enzymes/transition%20state.swf

• if this extra lesson does not help PLEASE come see Dr. Nugent

• Thank you