CHEMIOSMOTIC HYPOTHESIS_PRIYA JHA k.pptx

The chemiosmotic hypothesis explains how cells produce energy.
It describes the process of ATP synthesis through the movement of ions across a membrane.
This hypothesis is essential for understanding cellular respiration and photosynthesis.
It provides a framework for studying the role of ion gradients in various cellular processes.
Understanding the chemiosmotic hypothesis helps in developing treatments for diseases related to energy metabolism

1. Duration: 4 5 min CLASS XI PRIYA JHA JHA PHOTOSYNTHESIS IN HIGHER PLANTS TOPIC: CHEMIOSMOTIC HYPOTHESIS

2. Gist of The Topic The chemiosmotic hypothesis explains how cells produce energy. It describes the process of ATP synthesis through the movement of ions across a membrane. This hypothesis is essential for understanding cellular respiration and photosynthesis. It provides a framework for studying the role of ion gradients in various cellular processes. Understanding the chemiosmotic hypothesis helps in developing treatments for diseases related to energy metabolism

3. Photosynthesis is a fundamental process by which plants convert light energy into chemical energy, using chlorophyll and various molecules to produce sugars and release oxygen. Chemiosmosis, as part of cellular processes, elucidates how ions move across membranes to generate energy, crucial for ATP synthesis.

4. In chemiosmotic Hypothesis Chemo related with so many chemicals, chemical equation and chemical reaction while Osmotic comes from the term osmosis means movement of water from region of high water potential towards the region of low water potential

5. The chemiosmotic hypothesis is a theory that explains how cells produce energy. The Chemiosmotic Hypothesis, proposed by Peter Dennis Mitchell , outlines this mechanism, highlighting its significance in cellular metabolism and signaling.  It suggests that energy is generated through the movement of ions across a membrane, creating an electrochemical gradient. This gradient powers the production of ATP, the cell’s energy currency.

6. The proton gradient that exists across the thylakoid membrane is causes the ATP- Adenosine Triphosphates to be created in this process.

7. Why is it Called Chemiosmotic Theory? It’s called Chemiosmotic Theory because it explains energy production via ion movement across membranes.

8. What are the Steps of Chemiosmosis?

9. Pre requisition

10. How are these lost electrons compensated ? The electrons which are lost it moves through a chain or ETC ( Electron Transport Chain) ( PQ → Cytb6f→PC) While it moves through the ETC a lot of energy is utilize for Chemiosmosis to generate ATP

11. Three main events are found during the process of chemiosmotic hypothesis:

12. A.Photolysis of water towards thylakoid lumen:(Hills Reaction) The splitting of water molecules or photolysis occurs at the lumen side of the membrane. With this process, H+, produced in the internal lumen, gets accumulated.

13. In PS II Chl a is continuously loosing electron and its electron is filled by electron released through splitting of water molecule molecule which takes place in lumen of thylakoid 2H2O+light energy → 4H + +4e - +O2 This e- is transferred to chlorophyll A of PSII Oxygen is released in to the atmosphere H + helps to increase the H + into the lumen of thylakoid.

14. B.Transfer of H+ from stroma to lumen as electrons move through photosystems: The primary acceptor located towards the outer side of the membrane transfers its electron to an H+ carrier; after this electron, transportation takes place, which removes a proton. When this H+ carrier molecule passes on its electron to an electron carrier present on the inner side of the membrane, the H+ is then released into the lumen of the membrane.

15. While electron transported from ( PQ → Cytb6f→PC) actually PQ capture one H + ion from outside (from stroma).This is becsuse electron is loosing its energy when transfered from PQ → Cytb6f→PC and hence energy PQ have energy to hold H + ion . During this process Cytb6f passes the H + ion in to the lumen of thylakoid and helps to increse the H + ion ingredient in to lumen of thylakoid.

16. C.NADPH reductase reaction occurs towards stroma: The NADP reductase enzyme is located on the stromal side of the membrane. Protons are necessary to reduce NADP+ to NADPH + ,H+, and these protons are removed from the stroma. So, within the chloroplast, protons in the stroma decrease in number, while protons accumulate in the lumen. It causes a decrease in the lumen pH and creates a proton gradient across the thylakoid membrane.

17. In PS I the lost electron due to Electron Transport System get compensated from the electron released by PS II(FD) received through Primary Electron Acceptor .FD is present in thylakoid membrane . There is an enzyme present in the outside membrane of thylakoid called NADPsynthtase . In the stroma of Chloroplast NADP uses electron received from FD and H+ with the help of enzyme NADPsynthtase to produce NADPH. This NADPH is required in the Dark Reaction.

18. Why are we interested in the proton gradient(H+)? or What are importance of highly filled H+ gradient This gradient is important because its breakdown triggers energy release. The gradient is broken down. H+, a proton, moves from the lumen to the stroma by gradient channel ATP synthase. ATP synthase has two portions: F1: Present on the outer side, in the stroma. It converts the ADP (adenosine diphosphate) to ATP (adenosine triphosphate). It protrudes on the other surface of the thylakoid membrane. It is actually an enzyme(ATP synthetase) F0: Present on the inner side, in the lumen. It is embedded in the membrane and forms a transmembrane channel that carries out the diffusion of protons across the membrane.

19. Recapitulation 1.The correct sequence of flow of electrons in the light reaction is (a)PSII, plastoquinone, cytochromes, PSI, ferredoxin (b)PSI, plastoquinone, cytochromes, PSII, ferredoxin (c)PSI, ferredoxin, PSII, (d)PSI, plastoquinone, cytochromes, PSII, ferredoxin 2.Fill in the blanks a. NADP reductase enzyme is located on _________________. b. Breakdown of proton gradient leads to release of _____________.

20. Recapitulation: Labelle the A,B C and D in this diagram .

21. Conclusion This process of chemiosmotic hypothesis concludes the whole ATP formation with reference to photolysis of water, NADP reduction and electron transport system. It involves different electron and proton carriers to accomplish the activity. ATP forms as the product of this whole procedure utilized in the biosynthesis of sugar and provides energy to the proper functioning of the plants.

22. Chemiosmotic Hypothesis