Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in carbohydrate molecules, such as sugars and starches, which are synthesized from carbon dioxide and water – hence the name photosynthesis, from the Greek phōs, "light", and sunthesis, "putting together". In most cases, oxygen is also released as a waste product that stores three times more chemical energy than the carbohydrates. Most plants, algae, and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies most of the energy necessary for life on Earth.
C4 carbon fixation or the Hatch–Slack pathway is one of three known photosynthetic processes of carbon fixation in plants. It owes the names to the 1960's discovery by Marshall Davidson Hatch and Charles Roger Slack that some plants, when supplied with 14CO2, incorporate the 14C label into four-carbon molecules first.
C3 carbon fixation is the most common of three metabolic pathways for carbon fixation in photosynthesis, along with C4 and CAM. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into two molecules of 3-phosphoglycerate through the following reaction:
The light compensation point (Ic) is the light intensity on the light curve where the rate of photosynthesis exactly matches the rate of cellular respiration. At this point, the uptake of CO2 through photosynthetic pathways is equal to the respiratory release of carbon dioxide, and the uptake of O2 by respiration is equal to the photosynthetic release of oxygen. The concept of compensation points in general may be applied to other photosynthetic variables, the most important being that of CO2 concentration – CO2 compensation point (Γ).
Howard Griffiths is a physiological ecologist. He is currently Professor of Plant Ecology in the Department of Plant Sciences at the University of Cambridge, and a Fellow of Clare College, Cambridge. He formerly worked for the University of Dundee in the Department of Biological Sciences. He applies molecular biology techniques and physiology to investigate the regulation of photosynthesis and plant water-use efficiency.
Marshall (Hal) Davidson Hatch AM (born 24 December 1932) was an Australian biochemist and plant physiologist. He was the Chief Research Scientist at the CSIRO Division of Plant Industry in Canberra. He is a Fellow of the Australian Academy of Science, a Fellow of the Royal Society, a Foreign Associate of the US National Academy of Science and was awarded Honorary Doctorates from the University of Göttingen and the University of Queensland. In Australia, in 1966, he elucidated, jointly with Charles Roger Slack, the C4 pathway for the fixation of carbon, which is also sometimes known as the Hatch-Slack pathway. He is now retired.
Malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+) (EC 1.1.1.40) or NADP-malic enzyme (NADP-ME) is an enzyme that catalyzes the chemical reaction in the presence of a bivalent metal ion:
A Dynamic Global Vegetation Model (DGVM) is a computer program that simulates shifts in potential vegetation and its associated biogeochemical and hydrological cycles as a response to shifts in climate. DGVMs use time series of climate data and, given constraints of latitude, topography, and soil characteristics, simulate monthly or daily dynamics of ecosystem processes. DGVMs are used most often to simulate the effects of future climate change on natural vegetation and its carbon and water cycles.
Min Chen is an Australian plant physiologist. She was born in China and educated in Northeast Normal University China - BSc in 1984 and MSc in 1987 and received her PhD in 2003 from The University of Sydney Australia. She is a Full Professor and Australian Research Council Future Fellow in the School of Biological Sciences at the University of Sydney. Her research is primarily concerned with elucidating the molecular and biochemical mechanism of the energy-storing reactions in photosynthetic organisms, especially the function of novel photopigments in oxygenic photosynthetic bacteria.
Photosynthesis systems are electronic scientific instruments designed for non-destructive measurement of photosynthetic rates in the field. Photosynthesis systems are commonly used in agronomic and environmental research, as well as studies of the global carbon cycle.
Graham Douglas Farquhar, is an Australian biophysicist, Distinguished Professor at Australian National University, and leader of the Farquhar Lab. In 2018 Farquhar was named Senior Australian of the Year.
The Mehler reaction is named after Alan H. Mehler, who, in 1951, presented data to the effect that isolated chloroplasts reduce oxygen to form hydrogen peroxide. Mehler observed that the H
2O
2 formed in this way does not present an active intermediate in photosynthesis; rather, as a reactive oxygen species, it can be toxic to surrounding biological processes as an oxidizing agent. In scientific literature, the Mehler reaction often is used interchangeably with the Water-Water Cycle to refer to the formation of H
2O
2 by photosynthesis. Sensu stricto, the Water Water Cycle encompasses the Hill reaction, in which water is split to form oxygen, as well as the Mehler Reaction, in which oxygen is reduced to form H
2O
2 and, finally, the scavenging of this H
2O
2 by antioxidants to form water.
Marilyn Ball is a professor at the College of Medicine, Biology and Environment at the Australian National University (ANU), and leader of the Ball (Marilyn) Lab for Ecophysiology of Salinity and Freezing Tolerance.
Sharon Anita Robinson is an Antarctic researcher known for her work on climate change and bryophytes. She is the Executive Director of the UOW Global Challenges Program and Leader of the Program's Sustaining Coastal and Marine Zones Challenge at the University of Wollongong. She is Deputy-Director Science Implementation and UOW Node Lead of the Securing Antarctica’s Environmental Future program, a Special Research Initiative on Excellence in Antarctic Science from the Australian Research Council, worth $36 million over the next seven years (2020-2026). Dr Robinson is a science facilitator for the Homeward Bound project, a leadership program for women in STEMM. She was a faculty member for HB3 (2018-2019) and HB5 (2020-2021) expeditions.
Thomas D. Sharkey is a plant biochemist who studies gas exchange between plants and the atmosphere. His research has covered (1) carbon metabolism of photosynthesis from carbon dioxide uptake to carbon export from the Calvin-Benson Cycle, (2) isoprene emission from plants, and (3) abiotic stress tolerance. Four guiding questions are: (1) how leaf photosynthesis affects plant yield, (2) does some carbon fixation follow an oxidative pathway that reduces sugar output but stabilizes photosynthesis, (3) why plants make isoprene, and (4) how plants cope with high temperature.
Photosynthesis converts carbon dioxide to carbohydrates via several metabolic pathways that provide energy to an organism and preferentially react with certain stable isotopes of carbon. The selective enrichment of one stable isotope over another creates distinct isotopic fractionations that can be measured and correlated among oxygenic phototrophs. The degree of carbon isotope fractionation is influenced by several factors, including the metabolism, anatomy, growth rate, and environmental conditions of the organism. Understanding these variations in carbon fractionation across species is useful for biogeochemical studies, including the reconstruction of paleoecology, plant evolution, and the characterization of food chains.
Sabeeha Sabanali Merchant is a Professor of Plant Biology at the University of California, Berkeley. She studies the photosynthetic metabolism and metalloenzymes In 2010 Merchant led the team that sequenced the Chlamydomonas genome. She was elected a member of the National Academy of Sciences (NAS) in 2012.
Charles Roger Slack was a British-born plant biologist and biochemist who lived and worked in Australia (1962–1970) and New Zealand (1970–2000). In 1966, jointly with Marshall Hatch, he discovered C4 photosynthesis.
Donald Richard Ort is an American botanist and biochemist. He is the Robert Emerson Professor of Plant Biology and Crop Sciences at the University of Illinois at Urbana-Champaign where he works on improving crop productivity and resilience to climate change by redesigning photosynthesis. He is a member of the National Academy of Sciences (NAS) and a fellow of the American Association for the Advancement of Science (AAAS) and American Society of Plant Biologists (ASPB).
Deborah Pierson Delmer is an American plant pathologist, and professor emeritus at University of California, Davis. She was one of the first scientists to discover the enzymes and biochemical mechanisms for tryptophan synthesis.
