Photosynthesis Images Show Splitting of the Water Molecule

Photosynthesis includes a molecular step called splitting of the water molecule and new images of this step were reported in the journal Nature. The images were taken at Arizona State University with a new technique called femtosecond crystallography. Femtosecond crystallography uses a very powerful x-ray laser to create images of crystals before they explode because of being hit by the x-ray beam. This process is extremely fast and the images are taken in fractions of a second.

This is an exciting step in being able to visualize what is happening in photosynthesis on a very low molecular level. Being able to observe the chemical reactions of molecules in images in very new. This new ability to watch splitting of the water molecule during photosynthesis has two beneficial outcomes. First, it allows scientists to better understand the basic process of photosynthesis. Secondly, it may offer hints on how water can be oxidized to create oxygen gas, which is needed in the atmosphere for animals to breath. A possible application for oxidizing water could be to create an oxygen atmosphere in a dome on the planet Mars. This would allow humans and other animals to walk around, breath the air and live in the dome.

Splitting of the water molecule in photosynthesis is an early step in the process of photosynthesis. It occurs as part of the photosystem II process in which the sun’s energy is absorbed by the photopigment chlorophyll, which is housed in the plant cell organelle called a chloroplast. In photosystem II, the energy from the sun is put into “energy packages”, such as ATP, and the energy is then transferred to a carbohydrate. Since humans are not plants and cannot engage in photosynthesis, they must eat carbohydrates to gain the energy from the sun needed to fuel bodily activities.

It has been reported that additional images of the process of photosynthesis are likely forthcoming and eventually a movie of the entire process might be available. Some day, students in a biology class might be able to watch the entire process of photosynthesis actually happening, rather than looking at diagrams in a Power Point presentation. It is not likely, however, that this movie will become a favorite on YouTube.

As most school children learn, the process of photosynthesis in plants gives the Earth its oxygen atmosphere. Plants breath out oxygen, as a byproduct of photosynthesis, and humans and animals breath the oxygen in. Humans and animals breath out carbon dioxide and this is what plants need to breath in. This reciprocity is the basis for one of the more important cycles in life on Earth.

Oxygen, as a byproduct of photosynthesis, actually comes from the splitting of the water molecule step. Water molecules are made of one oxygen atom and two hydrogen atoms, which therefore gives water the famous chemical notation H2O. During splitting of the water molecule, the O and H’s split and the H’s then enter the next step in the process of photosynthesis, which is called the electron transport system. The O’s are leftover and need to go somewhere, so the individual oxygen atoms join together two-by-two and form oxygen gas molecules. This oxygen gas is then breathed out of the plant leaf and the oxygen accumulates around the Earth and becomes part of the atmosphere. The technology that allows imaging of splitting of the water molecule in photosynthesis is exciting because it gives a close-up view of something that is very important to most life on Earth.

By Margaret Lutze

Nature World News
Science World Report