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Monday, October 22, 2012

Monday's Molecule #191

Last week's molecule was L-dopa. The winner was Raul A. Félix de Sousa (again, but this time only by four minutes!) [Monday's Molecule #190].

This week's molecule is much more complicated and it's also much more important. You need to identify this complex making sure you distinguish it from other similar complexes. You don't need to name the exact species but you should have some idea of which organisms have this complex and which ones don't. There's not enough room in the comments for the complete IUPAC name!

You'll get special bonus points (and the expensive lunch in the dining room instead of the pub) for explaining how an irreducibly complex structure like this could have evolved.

Post your answer as a comment. I'll hold off releasing any comments for 24 hours. The first one with the correct answer wins. I will only post mostly correct answers to avoid embarrassment. The winner will be treated to a free lunch.

There could be two winners. If the first correct answer isn't from an undergraduate student then I'll select a second winner from those undergraduates who post the correct answer. You will need to identify yourself as an undergraduate in order to win. (Put "undergraduate" at the bottom of your comment.)

Some past winners are from distant lands so their chances of taking up my offer of a free lunch are slim. (That's why I can afford to do this!)

In order to win you must post your correct name. Anonymous and pseudoanonymous commenters can't win the free lunch.

Winners will have to contact me by email to arrange a lunch date. Please try and beat the regular winners. Most of them live far away and I'll never get to take them to lunch. This makes me sad.

Comments are now open.

UPDATE: The molecule is photosystem I (PSI). Mikkel Rasmussen was the only one to give the correct answer.

Nov. 2009: Jason Oakley, Alex Ling
Oct. 17: Bill Chaney, Roger Fan
Oct. 24: DK
Oct. 31: Joseph C. Somody
Nov. 7: Jason Oakley
Nov. 15: Thomas Ferraro, Vipulan Vigneswaran
Nov. 21: Vipulan Vigneswaran (honorary mention to Raul A. Félix de Sousa)
Nov. 28: Philip Rodger
Dec. 5: 凌嘉誠 (Alex Ling)
Dec. 12: Bill Chaney
Dec. 19: Joseph C. Somody
Jan. 9: Dima Klenchin
Jan. 23: David Schuller
Jan. 30: Peter Monaghan
Feb. 7: Thomas Ferraro, Charles Motraghi
Feb. 13: Joseph C. Somody
March 5: Albi Celaj
March 12: Bill Chaney, Raul A. Félix de Sousa
March 19: no winner
March 26: John Runnels, Raul A. Félix de Sousa
April 2: Sean Ridout
April 9: no winner
April 16: Raul A. Félix de Sousa
April 23: Dima Klenchin, Deena Allan
April 30: Sean Ridout
May 7: Matt McFarlane
May 14: no winner
May 21: no winner
May 29: Mike Hamilton, Dmitri Tchigvintsev
June 4: Bill Chaney, Matt McFarlane
June 18: Raul A. Félix de Sousa
June 25: Raul A. Félix de Sousa
July 2: Raul A. Félix de Sousa
July 16: Sean Ridout, William Grecia
July 23: Raul A. Félix de Sousa
July 30: Bill Chaney and Raul A. Félix de Sousa
Aug. 7: Raul A. Félix de Sousa
Aug. 13: Matt McFarlane
Aug. 20: Stephen Spiro
Aug. 27: Raul A. Félix de Sousa
Sept. 3: Matt McFarlane
Sept. 10: Matt Talarico
Sept. 17: no winner
Sept. 24: Mikkel Rasmussen
Oct. 1: John Runnels
Oct. 8: Raúl Mancera
Oct. 15: Raul A. Félix de Sousa
Oct. 22: Mikkel Rasmussen


Mikkel Rumraket Rasmussen said...

This is photosystem I (PSI) from Thermosynechoccus elongatus. Only organisms that gain energy through photosynthesis, like plants and cyanobacteria, have such systems. The purpose of the system is to absort light and thus provide energy for the internal biochemistry of the organism.

Irreducibly complex structures such as these (like the now famous bacterial flagellum) usually consist of several related homologous proteins and seem to have evolved in a stepwise fashion involving multiple duplication events. The reason they are irreducibly complex now is that their constituent parts have been modified since their origin and have become necessary for the extant structure.

Jean-Marc Neuhaus said...

This image is a bad choice. Either you recognize it because you have seen the publication or you have no chance. The resolution is too low to identify the many prosthetic groups. There seem to be several heme-like groups and quinones, but this is not enough. You could have used a mobile or movable image.

Mikkel Rumraket Rasmussen said...

/Mikkel Rasmussen btw, and still not an undergraduate :)

Larry Moran said...

Sorry you feel that way. I thought it was pretty obvious. How many structures have so many heme groups and quinone-like cofactors? I admit that if you aren't aware of photosystems then you don't have a chance but that's the point.

The fact that the heme-like groups were colored green was an important hint.

Jean-Marc Neuhaus said...

Well, I hesitated between photosynthetic reaction centers and cytochrome bc1 or b6f complexes, but then Rumraket's answer was already visible.