Detailed Notes on Cellular Respiration and Photosynthesis Processes

Definition: Phosphorylation is the process of adding a phosphate group to a molecule.
ATP Formation: In cellular processes, inorganic phosphate (denoted as ext{P}_i) is added to adenosine diphosphate (ADP), resulting in the formation of adenosine triphosphate (ATP).
Environment: The inorganic phosphate is free in the environment and not derived from another molecule.

Chemiosmosis vs. Osmosis: While osmosis involves the movement of water, chemiosmosis refers to the movement of hydrogen ions (H+) across a membrane, particularly in mitochondria.
Role of the Membrane: Chemiosmosis occurs through a biological membrane, driven by the creation of a gradient of hydrogen ions.
Oxidative Phosphorylation: The process is part of oxidative phosphorylation that ties together the electron transport chain (ETC) and ATP synthesis, making it vital for ATP production.

Function: ATP synthase is an enzyme that acts as a proton pump, facilitating the movement of protons across a membrane and synthesizing ATP as protons flow back through it.
Gradient: The electron transport chain (ETC) works against proton concentration gradients, creating stored energy that ATP synthase uses to convert ADP to ATP.

Electron Transport Chain (ETC): The ETC uses oxygen as the final electron acceptor, allowing the process to continue and produce water as a byproduct.
Energy Yield: The theoretical yield of ATP from one glucose molecule can range from 26 to 36 ATP, depending on the efficiency of the respiratory process.

Alternative Energies: Apart from glucose, organisms can derive energy from fats and proteins. The entry point in cellular respiration process varies by molecule type.
Energy Pathways: Different compounds may enter glycolysis or other metabolic pathways based on their structure and energy content.

Anaerobic vs. Aerobic Respiration: In the absence of oxygen, anaerobic respiration may occur, using non-oxygen electron acceptors.
Fermentation: This process allows cells to continue producing ATP via glycolysis by converting pyruvate into other compounds (e.g., lactic acid or ethanol) to free up NAD+/NADH.
Types of Fermentation:
- Alcohol Fermentation: Converts pyruvate to ethanol and CO2, commonly performed by yeast.
- Lactic Acid Fermentation: Converts pyruvate to lactic acid, common in muscle cells during intense exercise.

Summary Equation: Photosynthesis converts CO2 and water into glucose and oxygen using light energy, displaying an inverse relationship to cellular respiration.
Stages:
- Light-Dependent Reactions: Occur in the thylakoids of chloroplasts, where light energy splits water molecules and generates ATP and NADPH.
- Calvin Cycle (Light-Independent Reactions): Takes place in the stroma, using ATP and NADPH to fix carbon dioxide into glucose.
Key Pigment: Chlorophyll absorbs red and blue light, reflecting green, and is vital for capturing light energy during photosynthesis.

Light Independent Reactions: Often misleadingly named dark reactions as they do not occur in complete darkness. They require components from light-dependent reactions to produce glucose.
Role of Compounds: The final product of the Calvin Cycle is glyceraldehyde-3-phosphate (G3P), which can be converted into glucose.