Biological complexity: contingency planning photosynthesis (Introduction)

by David Turell , Wednesday, May 05, 2021, 22:07 (1298 days ago) @ David Turell

To avoid sunburn plants have quantum tricks:

https://evolutionnews.org/2021/05/contingency-planning-in-the-cell-affirms-design/

"...Jacob S. Higgins et al. describe how “Photosynthesis tunes quantum-mechanical mixing of electronic and vibrational states to steer exciton energy transfer.” Plants know their QM (quantum mechanics) well enough to employ it like an overflow valve, steering excess energy into the quenching center.

"Photosynthetic light-harvesting antennae transfer energy toward reaction centers with high efficiency, but in high light or oxidative environments, the antennae divert energy to protect the photosynthetic apparatus. For a decade, quantum effects driven by vibronic coupling, where electronic and vibrational states couple, have been suggested to explain the energy transfer efficiency, but questions remain whether quantum effects are merely consequences of molecular systems. Here, we show evidence that biology tunes interpigment vibronic coupling, indicating that the quantum mechanism is operative in the efficient transfer regime and exploited by evolution for photoprotection. Specifically, the Fenna–Matthews–Olson complex uses redox-active cysteine residues to tune the resonance between its excitons and a pigment vibration to steer excess excitation toward a quenching site.

"It’s marvelous that evolution “exploited” this QM capability, isn’t it? How many mutations did it take to get that right?"

Comment: Sure, Designed by random mutations.