The Direction of Spontaneous Reactions (and what it takes to go the other way)

Life Requires Lots of Unfavorable Reactions –

How Is This Possible?

The “Nature of Life” – Coupling Favorable to Unfavorable Reactions

ATP – LIFE’S ENERGY CURRENCYATP = Adenosine Triphosphate

Energy is released when ATP is hydrolyzed (broken down by water) to ADP.

ATP is restored from ADP and an input of energy.

ATP’s energy is used to drive endergonic (energy-requiring) reactions.

ENZYMES SPEED UP CHEMICAL REACTIONS

Enzymes are biological catalysts – substances that speed a reaction without being altered in the reaction.

Most enzymes are proteins.

Enzymes are essential for life.

Model of the surface of an enzyme.

Enzymes Lower a Reaction’s Activation Energy

ENZYME ACTION

ENZYME ACTION

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

The Fit Between Enzyme and Substrate is Critical and Precise

Hexokinase, an enzyme (blue), binding its substrate, glucose (yellow).

ENZYME DEFICIENCY AND HEALTH

Most genetic disorders are due to a deficiency in enzyme function.

This archival photo shows three children with the enzyme deficiency that causes phenylketonuria.

Enzymes - Activity Temperature and pH effect enzyme

action

Enzymes - Activity Temperature and pH effect enzyme

action