Overview of photosynthesis. Life on earth obviously could not continue indefinitely in this manner without independent mechanism for synthesizing complex molecules from simple ones. The sun energy (photon energy), that is captured and changed into chemical energy, can be used to synthesize glucose. This process is called by photosynthesis. What do you know about photosynthesis? Which organism can do this process? And where it takes place? Can you explain the phases of photosynthesis simply?
Photosynthetic Pigments. Photosynthesis can occur in both procaryotes and eucaryotes. The photosynthesis eucaryotes include not only the higher green plants, but also lower form such as the multicellular green, brown, and red algae, and unicellular organism such as euglenoids, dinoflagellates, and diatoms. All photosynthetic cells contain one or more types of the class of green pigment known as chlorophylls, but not all photosynthetic cells are green. For the example: photosynthesis not only occurs in green spinach, but also occurs in red one. Why can it happen? What do the trapping pigments act on it? Please explain!
The equation of photosynthesis. It is a common misconception that photosynthesis in microorganisms is of minor importance, compared to photosynthesis in the familiar higher plants. Actually, it is believed that more than half of all the photosynthesis on the surface of the earth is carried out by unicellular organisms, particularly the algae, dinoflagellates, diatoms, and bacteria. The purple bacteria are two classes, sulfur bacteria (e.g. Chromatium) which require hydrogen sulfide, sulfur, or thiosulfate, and nonsulfur bacteria (e.g. Rhodospirillum rubrum) which require organic molecules for photosynthesis. Please write the common equation of photosynthesis! Are this equation same with the both purple bacteria? If it is different, please explain it clearly!
The equation of photosynthesis. Most of photosynthetic organism use water as electron or hydrogen donor to reduce carbon dioxide or other electron acceptors; as a consequence they evolve molecular oxygen. But in the sulfur purple bacteria photosynthesis experiment, photosynthesis can occur without water but exist H2S. What does H2S play act? Why is oxygen not formed by its reaction?
Light reaction. It was postulate many years ago that photosynthesis consist of two types of process, the light reactions and the dark reaction. What do the light reactions mean? What is the light for? How can the light, which is captured by pigment, induce electron transport?
When a suspension of green algae is illuminated in the absence of CO2 and then incubated with 14CO2 in the dark, 14CO2 is converted to [14C] glucose for a brief time. What is the significance of this observation with regard to the CO2 – assimilation process, and how is it related to the light reactions of photosynthesis? Why does the conversion of 14CO2 to [14C] glucose stop after a brief time?
Light reaction, photosystem. There is much evidence that there are two light reactions in oxygen-evolving plant photosynthesis. More evidence comes from studies of the quantum efficiency of photosynthesis in plant cells as a function of wave-lenght. Duysen postulated it into long-wavelenght reaction (photosystem I) and shorter-wavelenght reaction (photosystem II). Describe each photosystem reaction! What are interlationships between photosystem I and photosystem II or it related? The chloroplasts contain two types of reactive chlorophyll complexes. Please explain it related to this photosystems!
Light reaction, photosystem. Velocity of photosynthesis is measured from quantity of O2 which produced. The green plant is illuminated by 680 nm and 700 nm wavelength. The velocity of photosynthesis for 680 nm wavelength is higher than 700 nm wavelength. If we use the combination of the light to illuminate the green plant, the velocity of photosynthesis will arise quickly than we use each of the lights. Please explain it related to photosystem I and II.
Dark reaction (Calvin Cycle). It was postulate many years ago that photosynthesis consist of two types of process, the light reactions and the dark reaction. What do the dark reactions mean? Please draw and explain the pathway of the carbon fixation in reduce pentose cycle! KM value of CO2 in ribulose 1,5-biphosphate carboxylase is decrease if pH medium are increase. What is the influence of the CO2 velocity to ribulose biphosphate carboxylase reaction? How can CO2 maintenance the velocity of photosynthesis?
C4 pathway. In many plants that grow in the tropics (and in temperate-zone crop plants native to the tropics, such as maize, sugarcane, and sorghum) a mechanism has evolved to circumvent the problem of wasteful photorespiration. The step in which CO2 is fixed into a three-carbon product, 3-phosphoglycerate, is preceded by several steps, one of which is temporary fixation of CO into a four carbon compound. Plants that use this process are referred to as C4 plants, and the assimilation process as C4 metabolism or the C4 pathway. Where does the C4 pathway occur? Draw and explain this pathway clearly? What are the different between C4 pathways with C3 pathway? How Does the C4 plant take CO2?
CAM Plants. Plants have a special adaptation to restrict the photorespiration effect. This adaptation occurs in C4 plants and CAM plants. Many CAM Plants grow in hot and dry environments, such as cactus and pineapple. In these plants, stomates close during the day and open during the night. Why would CAM plants close their stomates during the day? What are the different between C4 plants and CAM plants in CO2 fixation? Please explain CO2 fixation in CAM Plants!
C3 and C4 pathway. The plant genus Atriplex includes some C3 and some C4 species. From the data in the plots below (species 1, species 2), identify which is a C3 plant and which is a C4 plant. Justify your answer in molecular terms that account for the data in the plot.
