Review of Vitamins, Enzymes, and ATP-ADP Cycle PDF

**VITAMINS -** Many vitamins function as coenzymes, which are non-protein molecules that bind to enzymes and help them function properly. When a vitamin is deficient, the enzyme may not be able to bind to its substrate or catalyze the reaction efficiently. **Vitamin B12** is a common concern for ve...

**VITAMINS -** Many vitamins function as coenzymes, which are non-protein molecules that bind to enzymes and help them function properly. When a vitamin is deficient, the enzyme may not be able to bind to its substrate or catalyze the reaction efficiently. **Vitamin B12** is a common concern for vegans. This essential vitamin is primarily found in animal products, and its deficiency can lead to various health issues, including anemia and nerve damage. Lack of the vitamin as cofactor **Vitamin A -** Essential for healthy vision, especially in low-light conditions. **Vitamin B1 (Thiamine) - Helps convert carbohydrates into energy.** **ENZYMES** - **Enzymes are biological catalysts that accelerate chemical reactions within living organisms. Their primary function is to:  ** - **Lower the Activation Energy: Enzymes reduce the energy required to initiate a chemical reaction. This allows reactions to occur more quickly and efficiently at body temperature.  ** - **Increase Reaction Rate: By lowering the activation energy, enzymes significantly increase the rate of chemical reactions. This is crucial for maintaining life processes. As the substrate concentration increases, the rate of the enzyme-catalyzed reaction also increases.** - **Optimal Temperature (pH): Each enzyme has an optimal temperature at which it functions best. This is the temperature at which the enzyme\'s structure is most stable and its catalytic activity is highest. Example: Optimal pH for pepsin is 2** - **Temperature\'s Influence on Enzyme Activity;** - **Increased Temperature, Increased Activity: As temperature rises, molecular motion increases. This leads to more frequent collisions between enzyme and substrate molecules, increasing the likelihood of successful binding and reaction.** - **Denaturation at High Temperatures: If the temperature exceeds the optimal range, the enzyme\'s structure can become denatured. This means loss of enzyme structure and function.** - **Substrate concentration can influence enzymes activity; Increasing the substrate concentration generally increases the rate of reaction, up to a certain point.** - **Competitive inhibitors have a similar structure to the substrate molecule. This allows them to compete with the substrate for binding to the enzyme\'s active site. By occupying the active site, competitive inhibitors prevent the substrate from binding, thus reducing the enzyme\'s activity** - **Coupled reaction in ATP -- ADP Cycle; decreases the activation energy** - **Metabolic pathway; A metabolic pathway is a series of enzyme-catalyzed reactions that occur in a cell.** **COENZYMES AND COFACTORS FUNCTION:**  **Assisting in substrate binding:** They can help the enzyme recognize and bind to its substrate.  **Providing additional chemical groups for catalysis:** They can donate or accept functional groups needed for the reaction.    **Stabilizing the enzyme structure:** They can help maintain the enzyme\'s 3D shape, which is crucial for its function. **ATP- ADP CYCLE** ATP-ADP Cycle \| BioRender Science Templates **The endergonic reaction in the ATP-ADP cycle** is the **synthesis of ATP from ADP and inorganic phosphate (Pi)**. This reaction requires an input of energy to form a new phosphodiester bond between the phosphate groups. - **ATP hydrolysis** releases a significant amount of energy, which can be directly coupled to endergonic reactions to provide the necessary energy input. - **ATP hydrolysis provides the energy necessary for the cross-bridge cycling between actin and myosin filaments,** which is the fundamental mechanism of **muscle contraction.** - **ATP hydrolysis** provides the energy necessary for active transport proteins to pump molecules against their concentration gradient. - **ATP -- Primary energy currency of cells** **PHOTOSYNTHESIS/ LIGHT DEPENDENT REACTION**  - **Converts light energy into chemical energy** - In photosynthesis, water molecules are split into hydrogen ions (H+) and electrons. These electrons are essential for the light-dependent reactions, where they are used to generate ATP and NADPH - **Oxygen is the final electron acceptor in the electron transport chain**. It combines with electrons and protons to form water, releasing energy in the process. - **The Krebs cycle, also known as the citric acid cycle, takes place within the matrix of the mitochondria** - The overall efficiency of cellular respiration in converting glucose energy into ATP energy is around 40%. The remaining energy is lost as heat. - While glycolysis produces 4 ATP molecules, it consumes 2 ATP molecules in the initial steps. Therefore, the net **ATP production from glycolysis is 2 ATP molecules.** - **The electron transport chain between Photosystems I and II pump protons into the thylakoid lumen.** This creates a proton gradient across the thylakoid membrane, which is essential for ATP synthesis through chemiosmosis. - **Cyclic electron flow involves only Photosystem I.** It is a process that generates ATP without producing NADPH. Electrons are cycled back to Photosystem I, bypassing the electron transport chain and directly contributing to proton pumping and ATP synthesis. **CALVIN CYCLE / LIGHT INDEPENDENT REACTION** 4.1.6: Light-independent Reactions - Biology LibreTexts - The primary function of the Calvin cycle is to fix carbon dioxide from the atmosphere into organic molecules, such as glucose - RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) is the enzyme responsible for fixing carbon dioxide from the atmosphere into organic compounds during the Calvin cycle of photosynthesis. **CELLULAR RESPIRATION** - **Aerobic and Anaerobic Cellular Respiration** - Cellular respiration is the process by which cells break down glucose to produce energy in the form of ATP. - This process can occur in two ways: aerobically (with oxygen) or anaerobically (without oxygen). **Aerobic Respiration** Aerobic respiration is a more efficient process that involves three main stages: 1. **Glycolysis:** Glucose is broken down into pyruvate, producing a small amount of ATP. This process occurs in the cytoplasm and does not require oxygen. 2. **Krebs Cycle (Citric Acid Cycle):** Pyruvate is further oxidized, generating more ATP, NADH, and FADH2. This process occurs in the mitochondria.   3. **Electron Transport Chain (ETC):** NADH and FADH2 donate electrons to the ETC, which pumps protons across the mitochondrial membrane. This creates a proton gradient that drives ATP synthesis through ATP synthase.   **Overall Reaction:** C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP   **Anaerobic Respiration** Anaerobic respiration is less efficient and occurs when oxygen is not available. It primarily involves glycolysis followed by fermentation. There are two main types of fermentation:   1. **Lactic Acid Fermentation:** Pyruvate is converted into lactic acid. This process occurs in muscle cells during intense exercise.   ***Role in Training and Competition:*** ***Anaerobic respiration is primarily used for short bursts of high-intensity exercise, such as sprinting or weightlifting. It allows for rapid ATP production, but it is limited by the build up of lactic acid.  *** ***Aerobic respiration is crucial for endurance activities like long-distance running and cycling. Regular aerobic exercise enhances the body\'s capacity for aerobic metabolism, improving cardiovascular health and endurance.  *** ****** 2. **Alcoholic Fermentation:** Pyruvate is converted into ethanol and carbon dioxide. This process is used by yeast and some bacteria to produce alcohol and bread.   **Overall Reaction for Lactic Acid Fermentation:** C₆H₁₂O₆ → 2C₃H₆O₃ + 2ATP