Biology Discovery Note

The Process of Photosynthesis Overview Light-dependent reactions (Photochemical phase) , which involve Photosystem II (PSII) and Photosystem I (PSI) . Light-independent reactions (Calvin cycle) , which use the ATP and NADPH produced by the light-dependent reactions to fix carbon into glucose. Credit of Picture: https://mrkubuske.com/tag/dark-reactions/ Light-dependent Reactions These reactions occur in the thylakoid membranes of the chloroplast, where light energy is captured by chlorophyll pigments and used to produce ATP, NADPH, and oxygen. Photosystem II (PSII) and Photosystem I (PSI) are key components in this process. Photosystem II (PSII): Role : PSII is the first protein complex involved in the light-dependent reactions. Location : Thylakoid membrane. Process : Photon absorption : PSII absorbs light energy (photons) through chlorophyll and other pigments. Excitation of electrons : This energy excites electrons in chlorophyll molecules, raising them to a higher energy sta...

Cellular Respiration Overview Cellular respiration is the process by which cells break down glucose (or other organic molecules) in the presence of oxygen to produce ATP, the primary energy currency of the cell. It occurs in three main stages:  -  Glycolysis - Pyruvate Decarboxylation (Link Reaction) - Citric Acid Cycle (Krebs Cycle) - Electron Transport Chain (ETC) and Oxidative Phosphorylation . Credit of Picture: https://www.geeksforgeeks.org/ 1. Glycolysis (Occurs in the Cytoplasm) Purpose: Breaks down one molecule of glucose (6 carbon atoms) into two molecules of pyruvate (3 carbon atoms each), producing some ATP and NADH in the process. Raw Materials: 1 Glucose molecule (C₆H₁₂O₆) 2 NAD⁺ (for reduction to NADH) 2 ATP (for energy investment in early steps) Products: 2 Pyruvate molecules 2 NADH molecules 2 ATP (net gain, 4 ATP produced but 2 are used during the process) 2 H₂O molecules (released as byproducts) Summary: Glycolysis is anaerobic (doesn’t require oxygen)...