Reaction Rates and Evolution

University of North Carolina scientists have been studying the effect of temperature on extremely slow chemical reactions in order to determine whether life on Earth originated in a hot or cold environment and whether enough time has passed in order for life to have evolved to its current complexity. Their investigations suggest that the time required for evolution on a warmth earth is shorter than critics might expect.

They found that the influence of temperature on reaction rates varies dramatically. In one slow reaction, raising the temperature from 25 to 100^oC increased the rate 10 million fold!
High temperatures were probably a crucial influence on reaction rates when life began forming in hot springs and submarine vents. Later, the cooling of the earth provided elective pressure for primitive enzymes to evolve and become more sophisticated.

Using two different reaction catalysts which are not protein enzymes but that resemble the precursors to enzymes, they found that the catalyzed reactions were indeed less sensitive to temperature.

Reference
R. B. Stockbridge, C. A. Lewis, Y. Yuan, R. Wolfenden. Impact of temperature on the time required for the establishment of primordial biochemistry, and for the evolution of enzymes. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1013647107

Further Reading
http://www.ausetute.com.au/reactrate.html
http://www.ausetute.com.au/enerprof.html
http://www.ausetute.com.au/enzymes.html
http://www.ausetute.com.au/proteins.html

Study Questions

1. Explain why an increase in temperature generally speeds up the rate of a chemical reaction.
2. Define both the following terms :
   • catalyst
   • protein
   • enzyme
3. Draw an energy profile diagram to show the effect of a catalyst on a reaction.
   
4. Why would the researchers choose to use a non-protein based catalyst to study reactions that possibly occurred early on in the Earth's history?
5. Why is the study of catalyzed reactions, especially enzyme catalyzed reactions, important when studying the origins of life on Earth?
6. There is an enzyme, catalase, present in liver that speeds up the rate of decomposition of hydrogen peroxide. Design an experiment to demonstrate the effect of temperature change on this reaction.