The Working Cell: Ground Rules for Metabolism

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1. Explain the laws of Energy (thermodynamics) and give examples of how these laws apply to biology.

• Define energy
• Define potential energy and give examples
  • Note that chemical energy stored in the chemical bonds of molecules is a type of potential energy.
• Define kinetic energy and give examples
• Define conservation of energy (= the first law of thermodynamics) and give examples from biology and everyday life
• Define the second law of thermodynamics and give examples
  • Comment: Your text explains the second law as "All energy conversions generate heat". See figure 5.3
• Define entropy, explain why it is living things seem to violate the second law(but really do not)
• Heat is the total kinetic energy matter has due to random molecular motion.
  • Heat is not the same thing as temperature. Two beakers of water may be at the same temperature but if one beaker has twice as much water as the other that first beaker also has twice as much heat.
• Comment: Since whenever an energy conversion is done heat is produced, this also means the entropy of the surrounding environment increases.
• Might help to read my explanation of closed Vs open systems.
  • Comment: Organisms can appear to violate the increase in entropy of the universe because as long as they can take in matter and energy from the environment, organisms and groups of organisms can become more organized through time. This explains why evolution is NOT a violation of entropy. Eventually entropy wins though in that the total entropy of the universe will increase.
• Define calorie (c) and food calorie(C). See p 75.

2. Explain the basic concepts related to Energy and Cellular Work.

• Diagram the structure of ATP and ADP and how ATP helps cells do work.
• Diagram the ADP-ATP cycle (See figure 5.6, 5.7)
• Explain the function of electron transport systems in metabolism. (See page 92 fig 6.6)

3. Discuss Enzyme Structure and Function.

• Define the terms:
  • metabolism
  • enzyme
  • substrate
  • active site
  • activation energy
• Explain the Induced fit model in terms of enzyme - substrate interaction. See fig 5.9
• Describe enzyme function in terms of their effect on activation energy. See Fig 5.8. Also see my discussion.

4. Discuss some Factors affecting Enzyme Action

• Explain the relationship between pH and temperature and enzyme activity.
• Comment: remember denaturation from chapter 3?
• Explain two types of enzyme inhibition. See p 78-79 and fig 5.10
• Explain how feedback regulation of enzymes happens.
• Explain how penicillin works.

5. Summarize the major Transport Mechanisms used by cells.

• Define selective permeability with respect to the cell membrane. See section p 58
• Define diffusion and concentration explain why diffusion happens.
• Answer the question: why is diffusion across a membrane called passive transport?
• Define osmosis as a special kind of diffusion.
  • Predict the direction of net water flow for simple cells in different solutions.
  • Define the terms hypertonic, hypotonic and isotonic with respect to solutions
  • Contrast plants and animals in terms of how they avoid bursting in hypotonic solutions. See figures 5.12 - 5.14
• Define active transport
• Explain what type of energy is required for passive vs active transport
• Distinguish between the following "bulk" transport mechanisms p 82
  • endocytosis
  • exocytosis
  • pinocytosis
  • receptor mediated endocytosis. See cell uptake of cholesterol as an example.

6. Discuss the role of membranes in cell signaling.

• Define transduction and diagram the basic signal transduction pathway.

Be able to answer the following questions:

A student of Dr. Paul's said that when we eat, we create energy from our food. Is this statement correct? Why or why not?

Distinguish between simple diffusion and osmosis.

Both passive and active transport involve energy. What is the difference in the energy source for these two processes?

Kansans often kill slugs by sprinkling salt on them. Explain why this works in terms of osmosis.

Living things often appear at times to become more complex and organized over time (decreasing entropy). Is this a violation of the second law of thermodynamics? Explain.

Read the discussion on page 84 about directed evolution. How is this laboratory process similar and different from natural evolution involving natural selection?

pgd 09/13/02 revised 09/27/04