1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

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

9. 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

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

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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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