Differences between C3 and C4 plants


 

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Pseudocyclic Photophosphorylation

 Amon et al.(1954) demonstrated yet another kind of phosphorylation. They observed that: 1. In the absence of CO2 and NADP, it can produce ATP from ADP and PI in the presence of FMN (Flavine Mono Nucleotide) or vitamin K and O2. 2. The process is very simple. 3. It requires no chemical change except for the formation of ATP and water. 4. This is also called Oxygen-dependent FMN catalyzed photophosphorylation or pseudocyclic photophosphorylation involving reduction of FMN with the production of O2. II. PATH OF CARBON IN PHOTOSYNTHESIS (OR) DARK REACTION (OR) BLACKMAN’S REACTION (Activities found in stroma). The dark reaction of photosynthesis is purely enzymatic and slower than the primary photochemical reaction. It takes place in the stroma portion of chloroplast and is independent of light, i.e., it can occur either in the presence or absence of light. The main credit for investigating the sequences of dark reactions in photosynthesis goes to Melvin Calvin who was awarded Nobel P...
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Structure of Chloroplast

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  Each chloroplast is surrounded by a double membrane system. The external surface of the outer membrane is smooth whereas the inner membrane is thrown into lamellated structure showing two distinct regions, called Stroma and Grana Lamellae. Stroma Stroma is the main site for the dark reaction of photosynthesis. It forms the matrix (ground substance) of the chloroplast. In the matrix, the lamellae are loosely arranged. The lamellae found in the stroma are called as Stroma Lamellae . Besides these structures, ribosomes and osmophilic granules are also found in the stroma. Besides photosynthesis, lipid, protein, and nucleic acid metabolisms are also found to take place in the stroma region of the chloroplast. Grana Granum (= singular) is the most but complicated portion of the chloroplast. Light reaction of photosynthesis takes place only in the grana region of chloroplasts. About 40-60 grana are present in each chloroplast. In the granum region, the lamellae are compactly arranged j...
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Definition and Requirements of Photosynthesis

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  Photosynthesis can be defined as the formation of carbon-containing compounds from carbon dioxide and water with the help of green pigments and light while oxygen is liberated as the by-product. The simples equation for photosynthesis can be : Ruben and Kamen (1941) demonstrated that the source of liberated O2 is the water, through their experiment with oxygen isotope, 18 O as given below: Requirements of Photosynthesis Thus, the inputs or components of photosynthesis will be : 1. Carbon dioxide 2. Water 3. Light 4. Green pigments in chloroplasts of cells Output of Photosynthesis 1. Carbohydrates 2. Oxygen molecules
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