Biology 12

Chapter 2 Enzymes and Energy • MHR 59

CHAPTER 2 REVIEW

Summary of Expectations

Briefly explain each of the following points.

• The laws of thermodynamics govern the flow
  of energy in living and non-living systems. (2.1)


• The first law of thermodynamics states: Energy
  can neither be created nor destroyed but can
  be transformed from one form to another. (2.1)


• The second law of thermodynamics states:
  Energy cannot be transformed from one form
  to another without a loss of useful energy. (2.1)


• Entropy is a measure of randomness in a
  system. (2.1)


• In an endothermic reaction, the reactants
  contain less energy than do the products;
  therefore extra energy must be added for
  the reaction to take place. In an exothermic
  reaction, the reactants contain more energy
  than do the products; therefore there is a
  release of energy. Both reactions require
  activation energy to begin. (2.1)


• Enzymes are specialized proteins that catalyze
  reactions in cells by lowering the required
  activation energy. (2.2)


• Each step of a metabolic pathway, or each
  constituent reaction of the pathway, needs
  its own specific enzyme. (2.2)


• The induced-fit model describes how an
  enzyme binds with its substrate in order
  to catalyze a reaction. (2.2)


• The process by which an enzyme binds to a
  substrate, facilitates a reaction, releases the
  products of that reaction, and then binds to
  another substrate (beginning the process anew)
  is called the catalytic cycle. (2.2)


• The factors that affect enzyme activity are
  temperature, pH, inhibitors, cofactors, and
  coenzymes. (2.2)


• There are two kinds of enzyme inhibition —
  competitive inhibition and non-competitive
  inhibition. (2.2)
  
  
  • Cofactors and coenzymes also affect enzyme
    activity. They have been used to combat
    illness such as cancer and Chronic Fatigue
    Syndrome. (2.2)
  
  
  • The energy released by an exothermic reaction
    can be used to drive an endothermic one.
    Such a combination of reactions is called
    a coupled reaction. (2.3)
  
  
  • ATP is manufactured by coupled reactions. (2.3)
  
  
  • ATP is a molecule composed of the sugar
    ribose, the base adenine, and three phosphate
    groups. It is the common energy currency
    in all cells (2.3)
  
  
  • The energy released from the breakdown of
    ATP is used to fuel metabolic reactions. (2.3)
  
  
  
  

Language of Biology

Write a sentence using each of the following words or

terms. Use any six terms in a concept map to show

your understanding of how they are related.

• metabolism • induced fit


• energy • enzyme-substrate


• kinetic energy complex


• potential energy • catalytic cycle


• chemical energy • hydrothermal vents


• thermodynamics • inhibitors


• system • non-competitive


• closed system inhibition


• open system • allosteric site


• laws of thermodynamics • feedback inhibition


• entropy • activators


• activation energy • allosteric regulation


• exothermic reaction • competitive inhibition


• endothermic reaction • cofactors


• enzymes • coenzymes


• catalysis • restriction enzymes


• oxidative enzyme • prodrug


• hydrolytic enzyme • coupled reaction


• substrate • ATP


• metabolic pathway • active transport


• active sites • sodium-potassium
  pump

1.How do living things use energy?

2.Identify two different forms of energy.

3.Energy cannot be created or destroyed, but it
can be transformed. Outline the flow of energy
through living things on Earth.

4.How is an open system different from a closed

system?

5.What is the catalytic cycle?

6.How is activation energy important in

understanding chemical reactions?

UNDERSTANDING CONCEPTS