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Energy Flow and Enzymes
Energy Flow and Enzymes

Energy Flow and Enzymes Questions

Bring on the tough stuff
  1. You know that a biochemical reaction is spontaneous. Explain what must happen to heat in a system if the entropy of a system i) increases or ii) decreases.

  2. Describe two basic properties of an enzyme.

  3. How is a ribozyme like an enzyme made of amino acids? How is it different?

  4. Explain how understanding thermodynamics can give you important insights into why biological structures look the way they do. Give an example.

  5. How are different types of energy similar? How are they different? Explain, giving a clear definition of the first law of thermodynamics.

  6. Give three examples of how enzymes are used in products you use or consume every day.

  7. List the two main outputs of catabolic pathways.

  8. Give five examples of objects that have potential energy.

Energy Flow and Enzymes Answers

  1. Answer: Entropy refers to the amount of disorder in a system. Heat is basically the most disordered form of energy, so if entropy is increasing, the heat in the system must also be increasing. If entropy is decreasing, the heat must also be decreasing.
     
  2. Answer: The first basic property of an enzyme is that it does not change the thermodynamic properties of a reaction. An enzyme does change the activation energy to help the reaction become favorable thermodynamically. The second basic property of enzyme is that they are unchanged by the biochemical reaction; that is, they are not consumed or modified.
     
  3. Answer: A ribozyme is like an enzyme in that it has the same basic properties of an enzyme. Therefore, ribozymes do not change the thermodynamic properties of a reaction and are not consumed or modified during a reaction. However, a ribozyme has a strand of RNA as part of its catalytic site.
     
  4. Answer: Biological structures look the way they do because of the thermodynamic principles underlying their structures.  For example, the cellular membrane is oriented such that the lipophilic, or hydrophobic, parts of the lipid membrane are kept away from water while the hydrophilic parts of the lipid interact with water. This conformation is the most thermodynamically favorable one for these particular lipids to assume.
     
  5. Different types of energy, such as heat energy or work energy, are similar in that they can never be created or destroyed. The first law of thermodynamics, therefore, applies to both. Different types of energy are so because it is harder to turn one kind of energy into another kind.
     
  6. Enzymes are used in many facets of everyday life. For example, lactose intolerant people eat milk treated with lactase, the enzyme that breaks down lactose. Also, enzymes are used in the process of making cheese. Finally, enzymes are often added to cleaning products, such as laundry detergent, to make them more effective.
     
  7. Catabolic pathways produce smaller building blocks that can be used to make other biological molecules. They also generate energy to fuel anabolic pathways.
     
  8. Potential energy is the energy an object has because of its position. For example, a skydiver has potential energy before he jumps, a rock sitting on a high ledge has potential energy before it falls, and a car parked up hill has potential energy before rolls down. However, there is also potential energy in chemicals like fossil fuels and wood. This energy is chemical potential energy.
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