Biological complexity:photosynthesis new research (Introduction)

by David Turell , Wednesday, March 28, 2018, 18:34 (2432 days ago) @ David Turell

Photosynthesis occurs very rapidly. We are still unraveling its complexity:

https://phys.org/news/2018-03-photosynthesis-vibrations-traffic.html

"Plants and algae soak up sunlight and transfer the energy using proteins holding colored pigments. A pigment energized by a photon can pass that excitation energy to another nearby pigment—like passing the baton between runners in a relay. By repeating this process the photon's energy is carried to the reaction center where it is used to produce oxygen and power plant growth.

"Scientists have long wondered how plants move this energy so quickly and efficiently across the large collections of pigments surrounding each reaction center.

"In this study, researchers focused on one photosynthetic protein known as PC645. Using computer simulations and experimental data, they found that PC645 controls where energy goes by tuning the vibrations of pigments to enhance energy transport along specific routes.

"'You can imagine these proteins using the vibrations of different pigments like traffic signals that send excitations in one direction or another," explains Bennett, who was in Toronto for the CIFAR Bio-inspired Solar Energy program meeting.

"For example, when a 'blue' pigment is excited it could pass the excitation to a number of different neighboring pigments with similar energies. By controlling the vibrations, proteins can direct the 'blue' pigment to pass the excitation to a specific 'red' pigment thereby skipping over pigments with intermediate colours.

"'The weird thing is that when you run the experiments, the excitation doesn't step down an energy ladder. It jumps from the very highest rung to the very lowest rung and never touches anything in the middle. It makes you wonder—why? And more importantly, how?" says Bennett.

"Previously, researchers thought this could only be explained by quantum effects like entanglement. Vibronic coherence—the entanglement between electron and vibrational motion—was thought to be necessary for the fast jumps between very different energy levels. However, this new research suggests that what is needed is not vibronic coherence, but a large band of vibrations that bridge the energy gap between two pigments.

"'From a material perspective, this kind of classical mechanism is more useful because it's robust to reasonable levels of disorder that current synthetic techniques can achieve," Bennett says."

Comment: this energy transfer system is very complex. When this process appeared in cyanobacteria and algae it is so irreducibly complex it had to be p=put together all at once or it would not have worked. It had to be designed.