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Chapter 8. An Introduction to Metabolism. Metabolism. The totality of an organism’s chemical reactions http://www.elmhurst.edu/~ chm/vchembook/images/590metabolism.gif. 2 types of reactions in metabolic pathways. Anabolic and catabolic Which reactions release energy?

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chapter 8

Chapter 8

An Introduction to Metabolism

metabolism
Metabolism
  • The totality of an organism’s chemical reactions
  • http://www.elmhurst.edu/~chm/vchembook/images/590metabolism.gif
2 types of reactions in metabolic pathways
2 types of reactions in metabolic pathways
  • Anabolic and catabolic
  • Which reactions release energy?
  • Which reactions consume energy?
  • Which reactions break down molecules?
  • Which reactions build up larger molecules?
  • Which reactions are considered “uphill”?
  • What type of reaction is photosynthesis?
  • What type of reaction is cellular respiration?
forms of energy
Forms of Energy
  • Contrast kinetic energy with potential energy.
  • Which type of energy does water behind a dam have? A mole of glucose?
  • http://upload.wikimedia.org/wikipedia/commons/thumb/5/57/Hydroelectric_dam.svg/1280px-Hydroelectric_dam.svg.png
  • http://thumbs.dreamstime.com/z/glucose-molecule-11063520.jpg
the free energy of a reaction tells us whether the reaction occurs spontaneously
The free-energy of a reaction tells us whether the reaction occurs spontaneously
  • What is free energy? What is its symbol?
    • Endothermic - absorbs heat, H > 0
    • Exothermic - releases heat,H < 0
  • Reactions can also be classified according to the change in the free energy of the reaction:
    • Endergonic - NON-SPONTANEOUS, G > 0
    • Exergonic - SPONTANEOUS, G < 0
cellular respiration vs photosynthesis
Cellular Respiration vs Photosynthesis
  • Is cellular respiration an endergonic or an exergonic reaction? What is ∆G for this reaction?
  • Is photosynthesis endergonic or exergonic? What is the energy source that drives it?
  • \
atp powers cellular work by coupling exergonic reactions to endergonic reactions
ATP powers cellular work by coupling exergonic reactions to endergonic reactions
  • List the three main kinds of work that a cell does. Give an example of each.
  • 1. Chemical work
  • 2. Transport work
  • 3. Mechanical work
atp adenosine triphosphate
ATP – Adenosine Triphosphate

W

Which bond is likely to break?

slide9
ATP
  • By what process will that bond break?
  • When the terminal phosphate is broken, a molecule of inorganic phosphate Pi is formed, and energy is ___________?
  • For this reaction ATP  ADP + Pi, ∆G = ?
how atp performs work
How ATP Performs Work
  • What is energy coupling? See Fig. 8.10
  • In many cellular reactions, a phosphate group is transferred from ATP to some other molecule in order to make the second molecule less stable. The second molecule is said to be ____________.
enzymes speed up metabolic reactions by lowering energy barriers
Enzymes speed up metabolic reactions by lowering energy barriers
  • http://www.indiana.edu/~oso/animations/SN2%2BE.html
  • What is a catalyst?
  • What is activation energy? See Fig. 8.14
review of energy profile of an exergonic reaction
Review of energy profile of an exergonic reaction
  • What effect does an enzyme have on EA?
  • Is ∆G positive or negative?
  • How is ∆G affected by the enzyme?
catalysis in the enzyme s active site
Catalysis in the Enzyme’s Active Site
  • http://bio1151.nicerweb.com/Locked/media/ch08/08_17CatalyticCycle.jpg
  • What is meant by induced fit?
  • Explain how protein structure is involved in enzyme specificity.
  • Enzymes use a variety of mechanisms to lower activation energy. Describe four of these mechanisms.
4 mechanisms
4 Mechanisms
  • 1. acting as a template for substrate orientation
  • 2. stressing the substrates and stabilizing the transition state
  • 3. providing a favorable microenvironment
  • 4. participating directly in the catalytic reaction
effects of local conditions on enzyme activity
Effects of Local Conditions on Enzyme Activity
  • Many factors can affect the rate of enzyme action. Explain each factor listed below.
  • A. Initial concentration of substrate
  • B. pH
  • C. Temperature
  • Why can extremes of pH or very high temperatures affect enzyme activity?
  • Name a human enzyme that functions well in pH 2. Where is it found?
effects of local conditions on enzyme activity1
Effects of Local Conditions on Enzyme Activity
  • Distinguish between cofactors and coenzymes. Give examples of each.
  • Compare and contrast competitive inhibitors and noncompetitive inhibitors.
  • http://bcs.whfreeman.com/thelifewire/content/chp06/0602001.html