Photosynthesis OXYGENIC AND ANOXYGENIC.pptx

Photosynthesis is a fundamental biological process that enables plants, algae, and some bacteria to convert light energy from the sun into chemical energy in the form of glucose, which fuels their growth and development. This process occurs primarily in the chloroplasts of plant cells, where chlorophyll, the green pigment, captures sunlight. The basic equation for photosynthesis can be simplified as carbon dioxide (CO₂) and water (H₂O), in the presence of light energy, yielding glucose (C₆H₁₂O₆) and oxygen (O₂).

The process can be divided into two main stages: the light-dependent reactions and the light-independent reactions (or Calvin cycle). In the light-dependent reactions, which occur in the thylakoid membranes of the chloroplasts, sunlight is absorbed by chlorophyll and used to split water molecules, releasing oxygen as a byproduct. This phase also generates the energy carriers ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are essential for the next stage.

In the Calvin cycle, which takes place in the stroma of the chloroplasts, the ATP and NADPH produced in the light-dependent reactions are used to convert carbon dioxide from the atmosphere into glucose. This process involves a series of chemical reactions, starting with the fixation of carbon dioxide by the enzyme RuBisCO, forming a three-carbon compound. Through a series of transformations, these carbon compounds are eventually converted into glucose, which the plant can use for energy or store for later use.

Photosynthesis is not only crucial for the survival of plants but also for life on Earth. The oxygen released during the process is essential for the respiration of most living organisms. Additionally, photosynthesis forms the base of the food chain, providing the energy that fuels all life forms. Plants use the glucose produced to grow, develop, and reproduce, and this stored energy is passed on to herbivores and subsequently to carnivores in a cascading flow of energy through ecosystems.

Beyond its role in energy production and oxygen release, photosynthesis has a profound impact on global carbon cycles. By absorbing carbon dioxide from the atmosphere, plants help mitigate the effects of climate change. Forests, grasslands, and other plant ecosystems act as carbon sinks, storing carbon that would otherwise contribute to the greenhouse effect.

In summary, photosynthesis is an elegant and efficient process that sustains life on Earth by converting solar energy into a usable form for living organisms, producing oxygen, and regulating atmospheric carbon levels. Understanding this process not only highlights the importance of plants in our ecosystems but also emphasizes the delicate balance of natural processes that sustain the planet.

1. Submitted by :- Mayank Kumawat Course :- BSc. (H) Microbiology Submitted to :- Dr. Deepti Ma’am Photosynthesis : Oxygenic And Anoxygenic

2. Photosynthesis T he process by which green plants and certain other organisms transform light energy into chemical energy. During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds. Photosynthesis convert radiant or solar energy into chemical energy.

3. OXYGENIC PHOTOSYNTHESIS The oxidation of H 2 O releases molecular oxygen as a by-product. Since oxygen is released, the photosynthesis in such entities is referred to as oxygenic photosynthesis E xamples – Cyanobacteria and algae The equation for oxygenic photosynthesis is as follows – 6C 2 O + 12 H 2 O + Light ——-> C 6 H 12 O 6  + 6O 2  + 6 H 2 O. It occurs in two stages – light dependent reaction and light-independent reaction Light-dependent reaction – sequence of reactions occurring in the chloroplast (grana) necessitating solar energy. Light is used for the synthesis of ATP, water is photolysed into oxygen and hydrogen ion and free-electron carrier Light independent reaction – sequence of reactions occurring in the chloroplast (stroma). It aids in producing carbohydrates from carbon dioxide molecules by the process of reduction

4. Light independent reaction

5. Light Dependent Reaction

6. Photosynthetic Bacteria They are special types of bacteria that contain light absorbing pigments and reaction centres which make them capable of converting light energy into chemical energy. Cyanobacteria contain chlorophyll while other forms of bacteria contain bacteriochlorophyll. Bacteriochlorophyll resembles chlorophyll, it absorbs light of a longer wavelength than chlorophyll. Bacteriochlorophyll a is the most common form of bacteriochlorophyll but other forms include b, c, d, e, f and g.

7. Oxygenic Photosynthetic Bacteria They perform photosynthesis in a similar manner to plants. They contain light – harvesting pigments, absorb carbon dioxide, and release oxygen. Cyanobacteria or cyanophyta are the only form of oxygenic photosynthetic bacteria known to date. There are, however, several species of cyanobacteria. They are often blue-green in colour and are thought to have contributed to the biodiversity on earth by helping to convert the earth’s early oxygen-deficient atmosphere to an oxygen-rich environment. This transformation meant that most anaerobic organisms that thrived in the absence of oxygen eventually became extinct and new organisms that were dependent on oxygen began to emerge.

8. Anoxygenic Photosynthetic Bacteria They consume carbon dioxide but do not release oxygen. These include :- Green and purple bacteria Filamentous Anoxygenic Phototrophs (FAPs) Phototrophic Acidobacteria , Phototrophic Heliobacteria. The reason behind the name “PURPLE” “SULFUR” Bacteria is because is of the colour that is seen. These bacteria are seen purple to pink. This is because of the presence of carotenoids in the bacterial chlorophyll. The bacterial chlorophyll produces a pigment . This pigmented element in their structure gives the purple bacteria colonies occur in many numbers, purple to pink colour surface or water is observed even in naked eyes.

9. Phototrophic Acidobacteria Commonly found in acidic habitats Acidobacteria belong to the kingdom bacteria. As such, they are prokaryotic cells that lack a true nucleus and membrane-bound organelles. This is an ancient group whose members lack the outer membrane. Consists of a wide variety of organisms that can be found in different environments across the world (metal-contaminated soils to hot springs, etc.). They found in a lot of soils and are fairly diverse. However, not much is known about this grouping of bacteria, because they are fairly new, the first being found in 1991.

10. Phototrophic Heliobacteria Also found in soils, especially water-saturated fields, like rice paddies. They use a particular type of bacteriochlorophyll, labelled g, which differentiates them from other types of photosynthetic bacteria. They are photoheterotrophs, which means that they cannot use carbon dioxide as their primary source of carbon. Heliobacteria are strictly anaerobic, anoxygenic phototrophic bacteria. Have a Gram-positive cell structure and are capable of producing heat-resistant endospores. Phototrophy in heliobacteria is carried out using an FeS -type homodimeric reaction centre that represents the simplest known photosynthetic apparatus. Heliobacteria and green- sulfur bacteria employ a similar contingent of electron transfer cofactors, the polypeptides that bind the cofactors are significantly different.

11. Green and Red filamentous anoxygenic Phototrophs Previously called green non-sulphur bacteria, until it was discovered that they could also use sulfur components to work through their processes. This type of bacteria uses filaments to move around. The colour depends on the type of bacteriochlorophyll the particular organism uses. This form of bacteria can either be Photoautotrophic :- This means they create their own energy through the sun’s energy. Chemoorganotropic :- which requires a source of carbon; or photoheterotrophic, which, as explained above, means they don’t use carbon dioxide for their carbon source.

12. Applications of Photosynthesis Bacteria Water purification, bio-fertilizers, animal feed and bioremediation of chemicals among many others. They are used in the treatment of polluted water since they can grow and utilize toxic substances such as H 2 S or H 2 S 2 O 3 . Researchers at Harvard’s Wyss institute have engineered photosynthetic bacteria to produce simple sugars and lactic acid.

13. Thank You !!