Energy and Enzymes Life requires energy. 2/25/2019 Energy and Enzymes Life requires energy. Almost all energy for life is derived from the sun. A “factoid” - The sun’s energy that strikes Earth each day is equivalent to one million Hiroshima-sized atomic bombs. Photosynthesis harnesses about 1% of that energy – 10,000 “atomic bomb equivalents” per day. G. Podgorski, Biol. 1010

Energy and Enzymes 2/25/2019 Chemistry and Life One unromantic but productive way of viewing life is to see it as a set of coordinated chemical reactions. This leads to an obvious question – What determines what chemical reactions are possible? G. Podgorski, Biol. 1010

Energy and Enzymes 2/25/2019 Chemical Reactions Whether a chemical reaction will or won’t occur under particular conditions is determined by the laws of thermodynamics. Keeping it simple - If the overall amount of order is decreased by a reaction, the reaction is favored. Generally, if energy is released in a reaction, the reaction is favored. G. Podgorski, Biol. 1010

The Direction of Spontaneous Reactions Energy and Enzymes The Direction of Spontaneous Reactions (and what it takes to go the other way) 2/25/2019 G. Podgorski, Biol. 1010

Life Requires Lots of Unfavorable Reactions – How Is This Possible? Energy and Enzymes 2/25/2019 Life Requires Lots of Unfavorable Reactions – How Is This Possible? By coupling favorable to unfavorable reactions. favorable reactions unfavorable reactions G. Podgorski, Biol. 1010

The “Nature of Life” – Coupling Favorable to Unfavorable Reactions Energy and Enzymes 2/25/2019 The “Nature of Life” – Coupling Favorable to Unfavorable Reactions G. Podgorski, Biol. 1010

ATP - Life’s Energy Currency Energy and Enzymes 2/25/2019 ATP - Life’s Energy Currency Energy is released when ATP is hydrolyzed (broken down) to ADP. ATP is restored from ADP and an input of energy. ATP’s energy is used to drive endergonic (energy-requiring) reactions. G. Podgorski, Biol. 1010

The Way ATP Often Works Energy and Enzymes 2/25/2019 G. Podgorski, Biol. 1010

Enzymes Speed Biochemical Reactions Energy and Enzymes 2/25/2019 Enzymes Speed Biochemical Reactions Enzymes are biological catalysts – substances that speed a reaction without being altered in the reaction. Most enzymes are proteins, some are RNA. Model of the surface of an enzyme. Enzymes are essential for life. G. Podgorski, Biol. 1010

Enzymes Lower a Reaction’s Activation Energy Energy and Enzymes 2/25/2019 Enzymes Lower a Reaction’s Activation Energy G. Podgorski, Biol. 1010

Energy and Enzymes 2/25/2019 Enzyme Action G. Podgorski, Biol. 1010

The Fit Between Enzyme and Substrate is Critical and Precise Energy and Enzymes The Fit Between Enzyme and Substrate is Critical and Precise 2/25/2019 Hexokinase, an enzyme (blue), binding its substrate, glucose (yellow). G. Podgorski, Biol. 1010

Many Enzymes Work by Altering the Shape of Their Substrates Energy and Enzymes 2/25/2019 Many Enzymes Work by Altering the Shape of Their Substrates The active site of an enzyme is where substrate is bound. G. Podgorski, Biol. 1010

Enzyme Deficiency and Health Energy and Enzymes 2/25/2019 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. G. Podgorski, Biol. 1010

Energy and Enzymes 2/25/2019 Metabolic Pathways The synthesis of biological molecules often requires many enzyme-catalyzed steps. The entire set of steps is a metabolic pathway. G. Podgorski, Biol. 1010

Energy and Enzymes 2/25/2019 Metabolic Pathways The metabolic pathway that produces tryptophan – an amino acid. This is one of hundreds of metabolic pathways essential for life. G. Podgorski, Biol. 1010

Enzyme Activity is Often Regulated Energy and Enzymes 2/25/2019 Enzyme Activity is Often Regulated Feedback inhibition - a common form of enzyme regulation in which the product inhibits the enzyme . G. Podgorski, Biol. 1010