Chirality
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[edit] Definition
In chemistry, a molecule is said to be chiral if it is different from its mirror-image.
The molecules of life tend to be homochiral: formed of "left-handed" amino acids and "right-handed" sugars.
[edit] Chirality and creationism
The fact that life is homochiral is sometimes used as an argument against chemical abiogenesis. The argument goes something like this:
- Life only works with left-handed amino acids and right-handed sugars. But only living things produce chiral molecules. To have life, you need chirality, but to have chirality, you need life. Therefore God made life by magic.
The flaw in this argument is that there are plenty of abiotic chemical reactions which produce chirality or amplify it. A sample of these is given in the references below.
[edit] Links and References
- Saghatelian, A., Y. Yokobayashi, K. Soltani and M. R. Ghadiri. 2001. A chiroselective peptide replicator; Nature 409: 797-801.
- Zepik, H. et al. 2002, Chiral amplification of oligopeptides in two-dimensional crystalline self-assemblies on water; Science 295: 1266-1269
- Takats, Zoltan, Sergio C. Nanita and R. Graham Cooks. 2003. Serine octamer reactions: indicators of prebiotic relevance; Angewandte Chemie International Edition 42: 3521-3523.
- Sandra Pizzarello and Arthur L. Weber Prebiotic Amino Acids as Asymmetric Catalysts, Science 20 February 2004: Vol. 303. no. 5661, p. 1151
- Martin Klussmann, Hiroshi Iwamura, Suju P. Mathew, David H. Wells, Jr Urvish Pandya, Alan Armstrong and Donna G. Blackmond; Thermodynamic control of asymmetric amplification in amino acid catalysis; Nature 441, 621-623 (1 June 2006)
- Pedro Cintas, Chirality of Living Systems: A Helping Hand from Crystals and Oligopeptides Angewandte Chemie International Edition, Volume 41, Issue 7 , Pages 1139 - 1145
- Ricardo, A., Carrigan, M. A., Olcott, A. N., Benner, S. A.. 2004 Borate Minerals Stabilize Ribose Science January 9; 303: 196
- Kenso Soai, Takanori Shibata, Hiroshi Morioka & Kaori Choji. Asymmetric autocatalysis and amplification of enantiomeric excess of a chiral molecule, Nature 378, 767 - 768 (28 December 1995);
- Cristobal Viedma, Chiral Symmetry Breaking During Crystallization: Complete Chiral Purity Induced by Nonlinear Autocatalysis and Recycling, Phys. Rev. Lett. 94, 065504 (2005)
