The evolution of photosynthetic organisms began approximately 2.5 billion years ago when cyanobacteria came into existence and first used water molecules for photosynthesis, releasing oxygen as a by-product and changing life forms on earth. After an endosymbiosis event involving a eukaryote and a cyanobacterium, red algae, green algae and glaucophytes diverged from its common ancestor, a eukaryotic photosynthetic organism. In this long process, various metabolic interactions in cells have changed dramatically. For example, when cyanobacteria, which had performed both photosynthesis and respiration until then, evolved into chloroplast, mitochondria became responsible for respiration. Yet, there was a lack of information of these aspects in glaucophytes which needed to be addressed in order to understand the diversity of photosynthetic regulation and metabolic interaction among primary symbiotic algae.
"From the view point of metabolic interactions, C. paradoxa is the primary symbiotic algae most similar to cyanobacteria," says Kintake Sonoike, a professor of plant and cell physiology at Waseda University. "Our findings provide valuable information for revealing how photosynthetic organisms evolved."
So how can these factors have an effect on the rate of photosynthesis? Lets start off with the light intensity. When the light intensity is poor, there is a shortage of ATP and NADPH, as these are products from the light dependent reactions. Without these products the light independent reactions can't occur as glycerate 3-phosphate cannot be reduced. Therefore a shortage of these products will limit the rate of photosynthesis. When the carbon dioxide concentration is low, the amount of glycerate 3-phosphate produced is limited as carbon dioxide is needed for its production and therefore the rate of photosynthesis is affected. Finally, many enzymes are involved during the process of photosynthesis. At low temperatures these enzymes work slower. At high temperatures the enzymes no longer work effectively. This affects the rate of the reactions in the Calvin cycle and therefore the rate of photosynthesis will be affected.
Antibiotic resistance in bacteria is a common problem. It results from the transfer of a gene that gives resistance to a specific antibiotic usually by means of a plasmid to a bacterium. Some bacteria will then have this gene and become resistant to the specific antibiotic while others will lack the gene and so will die if exposed to the antibiotic. Over time, the non-resistant ones will all die off as doctors vaccinate patients, but the resistant ones will survive. Eventually, the resistant ones will be the only ones left as a result of natural selection and so a new antibiotic must be created. However, this has to be done on a regular basis as the bacteria keep evolving and become resistant to multiple antibiotics.
In the next billion years following the evolution of aerobic photosynthesizing bacteria, the first cells arose which had lost the ability to carry out photosynthesis and thus the ability to manufacture their own food from inorganic material. These cells relied on organic material (other life) as their source of food. The food chain was begun.
Tokyo, Japan - Scientists have long studied which of the three primary photosynthetic eukaryotes (red algae, green algae, and glaucophytes) has come into existence first to unravel the biological mystery of algae evolution by analyzing their genetic information.
Despite learning that the structure of cyanelles, an organelle unique to glaucophytes, is most similar to the ancestral cyanobacteria among other organelles, these studies have not conclusively resolved the branching position of glaucophytes and left the early branching history of the three primary photosynthetic lineages uncertain.
IMAGE: The evolution of photosynthetic organisms began approximately 2.5 billion years ago when cyanobacteria came into existence and first used water molecules for photosynthesis.
The carbon dioxide in our atmosphere contains both 12C and 13C isotopes. When the carbon atoms of CO2 are captured by organisms in photosynthesis, the organisms show a definite preference for the light 12C isotope of carbon. They will incorporate the 12C isotope into the proteins, sugars, and other molecules that they synthesize preferentially to the heavier 13C isotope. Rocks that are 3.4 billion years old have been discovered which are enriched with the 12C isotope. The concentration of the 12C isotope shows the presence of photosynthesis. These early photosynthetic organisms used H2S as a source of hydrogen atoms instead of water and did not produce oxygen as a by-product.