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Energy and Enzymes

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.

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Energy and Enzymes

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  1. 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.

  2. 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?

  3. 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.

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

  5. By coupling favorable to unfavorable reactions. Life Requires Lots of Unfavorable Reactions – How Is This Possible? favorable reactions unfavorable reactions

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

  7. 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.

  8. The Way ATP Often Works

  9. Model of the surface of an enzyme. 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. Enzymes are essential for life.

  10. Enzymes Lower a Reaction’s Activation Energy

  11. Enzyme Action

  12. Hexokinase, an enzyme (blue), binding its substrate, glucose (yellow). The Fit Between Enzyme and Substrate is Critical and Precise

  13. Many Enzymes Work by Altering the Shape of Their Substrates The active site of an enzyme is where substrate is bound.

  14. 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.

  15. Metabolic Pathways The synthesis of biological molecules often requires many enzyme-catalyzed steps. The entire set of steps is a metabolic pathway.

  16. Metabolic Pathways The metabolic pathway that produces tryptophan – an amino acid. This is one of hundreds of metabolic pathways essential for life.

  17. Enzyme Activity is Often Regulated Feedback inhibition - a common form of enzyme regulation in which the product inhibits the enzyme .

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