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(Bio) (Chem) Photosynthesis: Plants Reveal a Secret

 
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adedios
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PostPosted: Tue Dec 20, 2005 2:06 pm    Post subject: (Bio) (Chem) Photosynthesis: Plants Reveal a Secret Reply with quote






Plants Reveal A Secret And Bring Researchers Nearer A Cleaner Future
Press Release
28 November 2005
European Synchrotron Radiation Facility

Researchers from Freie Universität Berlin identify a new step in photosynthesis

Using sunlight to power our homes and offices is an unaccomplished dream due to the still inefficient technology for a better use of solar energy. The study of photosynthesis in plants could provide new clues by explaining how they absorb almost 100% of the sunlight reaching them, and how they transform it into other forms of energy. Researchers Michael Haumann and Holger Dau, from the Freie Universität Berlin, used the X-ray source of the European Synchrotron Radiation Facility (ESRF) to investigate the kinetics of the photosynthesis process. They have confirmed the existence of a fifth step in the catalysis process converting water into oxygen, and have published their results in Science.

Chlorophyll in plants absorbs light from the sun, which then becomes energy used by the so-called "oxygen-evolving complex" to catalyse the splitting of water into molecular oxygen. This complex contains four manganese and one calcium atom that are known to be at the centre of the catalytic reaction. Five intermediate states have been proposed in the process of photosynthesis - a cycle known as the "Kok cycle" - but only four had been proved until recently. With the help of the ESRF, scientists have been able to identify the missing state, which is particularly important because it is directly involved in the molecular oxygen formation. They suggest, furthermore, an extension of the "Kok cycle" with an additional intermediate and propose a new reaction mechanism on a molecular basis for the release of dioxygen. This gives new insight into the mechanism of photosynthesis.

In order to study this process, the use of synchrotron light was crucial: "A very intense and stable X-ray beam is necessary to perform this study on such a complex, highly diluted protein present in the investigated spinach sample", explains Pieter Glatzel, head of beamline ID26, where the experiments were carried out. The researchers measured the fluorescence from the sample that is emitted after excitation with X-rays.

They flashed the sample with a laser and registered the change using X-ray fluorescence every 10 microseconds to find out how different oxidation states developed. When carefully analysing the reaction kinetics, they observed a time delay before the O2-evolving step. This delay unambiguously proved the existence of the long-searched for intermediate state.

How far away are we then from using the sun to power our daily lives? Michael Haumann, the main author of the publication, asserts that "these are important results that will make an impact in the photosynthesis community. They help our understanding of how solar energy is used in plants and contribute to the efforts to produce more efficient solar cells for our needs".

*************************************************************

What is photosynthesis?

http://library.thinkquest.org/.....nthsis.htm
http://www.realtrees4kids.org/sixeight/letseat.htm
http://www.cornwallwildlifetru.....hotsyn.htm
http://www.ktca.org/newtons/9/phytosy.html
http://biology.clc.uc.edu/cour.....otosyn.htm
http://web.mit.edu/esgbio/www/ps/intro.html
http://photoscience.la.asu.edu.....intro.html

What is inside a leaf?

http://www.ftexploring.com/pho.....plast.html

Why do leaves change color in autumn?

http://www.cornwallwildlifetru.....leaves.htm

What is solar energy?

http://www.fsec.ucf.edu/ed/sw/presentation1.html
http://www.eia.doe.gov/kids/en.....solar.html

Here is an example of how scientists study photosynthesis:

http://researchmag.asu.edu/stories/power.html

GAMES

http://www.scholastic.com/magi.....s/home.htm
http://www.energyhog.org/
http://www.academyofenergy.org/games.html
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adedios
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PostPosted: Tue Mar 13, 2007 7:19 am    Post subject: Progress toward Artificial Photosynthesis? Reply with quote

Progress toward Artificial Photosynthesis?
12 March 2007
Angewandte Chemie International

Plants can do it: they simply grab carbon dioxide out of the air and covert it into biomass. In this process, known as photosynthesis, the plants use light as their energy source. Chemists would also like to be able to use CO2 as a carbon source for their synthetic reactions, but it doesn’t work just like that. A team headed by Markus Antonietti at the Max Planck Institute for Colloids and Interfaces has now taken an important step toward this goal. As described in the journal Angewandte Chemie, they have successfully activated CO2 for use in a chemical reaction by using a special new type of metal-free catalyst: graphitic carbon nitride.

For the full article:

http://www3.interscience.wiley.....press.html
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PostPosted: Wed Apr 11, 2007 1:21 pm    Post subject: NASA predicts nongreen plants on other planets Reply with quote

NASA/Goddard Space Flight Center
11 April 2007

NASA predicts nongreen plants on other planets

NASA scientists believe they have found a way to predict the color of plants on planets in other solar systems.

Green, yellow or even red-dominant plants may live on extra-solar planets, according to scientists whose two scientific papers appear in the March issue of the journal, Astrobiology. The scientists studied light absorbed and reflected by organisms on Earth, and determined that if astronomers were to look at the light given off by planets circling distant stars, they might predict that some planets have mostly non-green plants.

"We can identify the strongest candidate wavelengths of light for the dominant color of photosynthesis on another planet," said Nancy Kiang, lead author of the study and a biometeorologist at NASA's Goddard Institute for Space Studies, New York. Kiang worked with a team of scientists from the Virtual Planetary Laboratory (VPL) at the California Institute of Technology, Pasadena, Calif. VPL was formed as part of the NASA Astrobiology Institute (NAI), based at the NASA Ames Research Center in California’s Silicon Valley.

"This work broadens our understanding of how life may be detected on Earth-like planets around other stars, while simultaneously improving our understanding of life on Earth," said Carl Pilcher, director of the NAI at NASA Ames. "This approach -- studying Earth life to guide our search for life on other worlds -- is the essence of astrobiology."

Kiang and her colleagues calculated what the stellar light would look like at the surface of Earth-like planets whose atmospheric chemistry is consistent with the different types of stars they orbit. By looking at the changes in that light through different atmospheres, researchers identified colors that would be most favorable for photosynthesis on other planets.

This new research narrows the range of colors that scientists would expect to see when photosynthesis is occurring on extrasolar planets. Each planet will have different dominant colors for photosynthesis, based on the planet’s atmosphere where the most light reaches the planet’s surface. The dominant photosynthesis might even be in the infrared.

"This work will help guide designs for future space telescopes that will study extrasolar planets, to see if they are habitable, and could have alien plants," said Victoria Meadows, an astronomer who heads the VPL. The VPL team is using a suite of computer models to simulate Earth-size planets and their light spectra as space telescopes would see them. The scientists' goal is to discover the likely range of habitable planets around other stars and to find out how these planets might appear to future planet-finding missions.

On Earth, Kiang and colleagues surveyed light absorbed and reflected by plants and some bacteria during photosynthesis, a process by which plants use energy from sunlight to produce sugar. Organisms that live in different light environments absorb the light colors that are most available. For example, there is a type of bacteria that inhabit murky waters where there is little visible light, and so they use infrared radiation during photosynthesis.

Scientists have long known that the chlorophyll in most plants on Earth absorbs blue and red light and less green light. Therefore, chlorophyll appears green. Although some green color is absorbed, it is less than the other colors. Previously, scientists thought plants are not efficient as they could be, because they do not use more green light.

According to scientists, the Sun has a specific distribution of colors of light, emitting more of some colors than others. Gases in Earth's air also filter sunlight, absorbing different colors. As a result, more red light particles reach Earth's surface than blue or green light particles, so plants use red light for photosynthesis. There is plenty of light for land plants, so they do not need to use extra green light. But not all stars have the same distribution of light colors as our Sun. Study scientists say they now realize that photosynthesis on extrasolar planets will not necessarily look the same as on Earth.

"It makes one appreciate how life on Earth is so intimately adapted to the special qualities of our home planet and Sun," said Kiang.


###
NASA GISS is a leading center in the study of Earth’s past, present and future climates, research that is vital for understanding how life impacts and is impacted by the atmosphere on other planets. The NAI, founded in 1997, is a partnership between NASA, 12 major U.S. teams and six international consortia. NAI's goal is to promote, conduct and lead integrated multidisciplinary astrobiology research and to train a new generation of astrobiology researchers.
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PostPosted: Fri Apr 13, 2007 10:04 am    Post subject: Quantum Secrets of Photosynthesis Revealed Reply with quote

Quantum Secrets of Photosynthesis Revealed
Lawrence Berkeley Laboratory
12 April 2007

BERKELEY, CA —Through photosynthesis, green plants and cyanobacteria are able to transfer sunlight energy to molecular reaction centers for conversion into chemical energy with nearly 100-percent efficiency. Speed is the key – the transfer of the solar energy takes place almost instantaneously so little energy is wasted as heat. How photosynthesis achieves this near instantaneous energy transfer is a long-standing mystery that may have finally been solved.

For the full article:

http://www.lbl.gov/Science-Art.....crets.html
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PostPosted: Wed May 02, 2007 11:21 am    Post subject: Protein enables discovery of quantum effect in photosynthesi Reply with quote

Protein enables discovery of quantum effect in photosynthesis

Taco shell protein

By Tony Fitzpatrick


May 1, 2007 -- When it comes to studying energy transfer in photosynthesis, it's good to think "outside the bun."

That's what Robert Blankenship, Ph.D., professor of biology and chemistry in Arts & Sciences at Washington University in St. Louis, did when he contributed a protein to a study performed by his collaborators at Lawrence Berkeley National Laboratory and the University of California at Berkeley.

For the full article:

http://news-info.wustl.edu/tip...../9362.html
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PostPosted: Thu Jul 26, 2007 1:55 pm    Post subject: Isoprene emission from plants -- a volatile answer to heat s Reply with quote

Blackwell Publishing Ltd.
26 July 2007

Isoprene emission from plants -- a volatile answer to heat stress


Isoprene is a hydrocarbon volatile compound emitted in high quantities by many woody plant species, with significant impact on atmospheric chemistry. The Australian Blue Mountains and the Blue Ridge Mountains in the Eastern United States are so called because of the spectral properties of the huge amounts of isoprenes emitted from the trees growing there. Although a positive correlation has been observed between leaf temperature and isoprene emission in plants, the physiological role of isoprene emission, which is clearly quite costly to the plant, is still under vigorous debate.

One of the most popular hypotheses suggests that isoprene protects the metabolic processes in the leaf, in particular photosynthesis (the process by which plants use light energy to fix CO2 and produce their own “food”), against thermal stress. To test this hypothesis, scientists Katja Behnke and Jörg-Peter Schnitzler from the Institute for Meteorology and Climate Research of the Research Centre Karlsruhe in Garmisch-Partenkirchen in Germany, together with colleagues from the Universities of Braunschweig and Göttingen, also in Germany, and British Columbia, in Canada, recently applied genetic engineering techniques to obtain transgenic Grey poplar (Populus x canescens) trees with decreased isoprene emission, and examined their tolerance to heat. Their findings have been published in The Plant Journal.

Behnke et al. engineered such poplar trees by suppressing the expression of the gene encoding isoprene synthase (ISPS), the enzyme producing isoprene, by RNA interference (RNAi). They then subjected these trees to transient heat phases of 38-42°C, each followed by phases of recovery at 30°C, and measured the performance of photosynthesis. In these experiments, Behnke et al. observed that photosynthesis in trees that no longer emitted isoprenes was much less efficient under such repeated “heat shocks” (a situation that is similar to what happens in nature, where temperatures around the leaves often oscillate, with short heat spikes). Thus, their results clearly indicate that isoprenes have an important role in protecting the leaves from the harmful effects of high ambient temperature.

How does isoprene confer heat tolerance? Does isoprene act as an antioxidant due to its chemical reactivity" And more generally: Is this effect of significance under natural conditions for poplar and other isoprene-emitting species" The researchers aim to analyse the biophysical and biochemical mechanisms of heat effects on photosynthesis and chloroplasts, and future long-term field trials will test whether the isoprene effect represents a positive adaptive trait for isoprene-producing species.
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PostPosted: Tue Nov 27, 2007 2:08 pm    Post subject: In the Dark, Plants Prepare for Light Reply with quote

In the Dark, Plants Prepare for Light
By Andrea Thompson, LiveScience Staff Writer

posted: 26 November 2007 02:14 pm ET

Every grade-schooler knows that plants need light to grow, but just how plants respond to light is a deceptively complex process that has long puzzled scientists.

A new study sheds light on this enigma by showing that plants actually get ready to respond to light (by growing, flowering or straining toward the light) while it’s still dark.

For the full article:

http://www.livescience.com/str.....light.html
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