Pre-Lecture Lesson 1.5: Energetic Trade-offs

What causes the reaction rate of an enzyme-catalyzed reaction to drop above the optimum?

What causes the reaction rate of an enzyme-catalyzed reaction to drop below the optimum?

enzyme denatures

low kinetic energy reduces ability to overcome even the reduced Ea

Why might you expect that all the thousands of enzymes and other kinds of proteins (motor proteins, etc.) in the cells of an individual generally have a very similar temperature optimum?

evolved to function well at normal body temperature of species

• How do ectotherms and endotherms compare in their energy requirements? All other things being equal, endotherms require _____ energy than ectotherms, as they require a _____ rate of cellular respiration to maintain their body temperatures.

• How might that affect their metabolic demand for gas exchange? Endotherms require a _____ rate of oxygen supply per unit time than ectotherms. This has consequences on their anatomy that puts constraints on what anatomical solutions are possible. For example, I expect _______ to require a greater need to optimize variables of Fick's Law in their respiratory and circulatory systems.

• more, higher

• higher, endotherms

What fraction of the energy that originally came down from the sun and hit the leaves of plants do you obtain when you eat meat from a cow?

0.1% of the energy that originally came down from the sun