Bioenergetics Biochemistry Semester-2

Notes on Biochemistry| Bioenergetics |B.Pharmacy 1st Year| 2nd Semester| Free notes| pharmacy notes download

Bioenergetics- Biochemistry notes 

Bioenergetics: - is a field of biochemistry and cell biology related to the flow of energy through biological systems. This is an active area of ​​biological research that combines biomass conversion research with the study of thousands of different cellular processes such as cellular respiration and many other metabolic and enzymatic processes that lead to the production and utilization of energy. forms such as adenosine triphosphate (ATP) molecules. That is to say, the purpose of bioenergetics is to explain how living things acquire and convert energy to make biological work. Therefore, the study of metabolic pathways is important for bioenergetics.

Bioenergetics is a component of biochemistry related to the forces involved in forming and breaking down chemical bonds into molecules found in living organisms. It can also be described as the study of the relationship of energy and the transformation of energy and biological change. The ability to utilize energy from a variety of metabolic processes is the property of all living things that contain earth science. Growth, development, anabolism and catabolism are some of the key processes in the study of biology, because the role of energy is fundamental to such biological processes. Life depends on the transformation of energy; living things survive due to the exchange of energy between tissues / cells and the external environment. Some organisms, such as autotrophs, can absorb energy from sunlight (through photosynthesis) without the need for nutrients and break down. Some organisms, such as heterotrophs, must absorb nutrients from the diet in order to support energy by breaking down chemical bonds in structures during metabolic processes such as glycolysis and the citric acid cycle. Importantly, as a direct result of the first law of thermodynamics, autotrophs and heterotrophs participate in a universal metabolic network — by eating autotrophs (plants), heterotrophs binding energy that begins to be transformed by plants during photosynthesis.

Types of reactions-: Exergonic reactions spontaneous chemical reactions that release energy. It is thermodynamically favored, with a negative ΔG (Gibbs free energy) value. During a reaction, energy needs to be applied, and this activation force drives the reactants from a stable state to a less stable state to a less stable state (see: linking reaction). Reactants are usually complex molecules that are broken down into simple products. All reactions are usually catabolic. Energy emissions (especially Gibbs free energy) are negative (i.e. ΔG <0) because the reactants' power is higher than that of the products.

Endergonic reactions are a potent anabolic chemical reaction. It is the opposite of an exergonic reaction. It has a positive ΔG, for example because ΔH> 0, which means it takes more energy to break down reactant bonds than supply products, i.e. products have weaker bonds than reactants. Therefore, the endergonic reaction is not thermodynamically positive and will not occur spontaneously at constant temperature. Additionally, endergonic reactions are usually anabolic.

Free energy received or lost (ΔG) in response can be calculated as follows: ΔG = ΔH - TΔS where ∆G = Gibbs free energy change, ∆H = enthalpy change, T = temperature (kelvins), and ∆S = change entropy.

Examples of major bioenergetic processes

• Glycolysis is the process of breaking down glucose into pyruvate, producing two molecules of ATP (per 1 molecule of glucose) in the process. When a cell has a higher concentration of ATP than ADP (i.e. has a high energy charge), the cell cannot undergo glycolysis, releasing energy from available glucose to perform biological work. Pyruvate is one product of glycolysis, and can be shuttled into other metabolic pathways (gluconeogenesis, etc.) as needed by the cell. Additionally, glycolysis produces reducing equivalents in the form of NADH (nicotinamide adenine dinucleotide), which will ultimately be used to donate electrons to the electron transport chain.
• Gluconeogenesis is the opposite of glycolysis; when the cell's energy charge is low (the concentration of ADP is higher than that of ATP), the cell must synthesize glucose from carbon- containing biomolecules such as proteins, amino acids, fats, pyruvate, etc.For example, proteins can be broken down into amino acids, and these simpler carbon skeletons are used to build/ synthesize glucose.
• The citric acid cycle is a process of cellular respiration in which acetyl coenzyme A, synthesized from pyruvate dehydrogenase, is first reacted with oxaloacetate to yield citrate. The remaining eight reactions produce other carbon-containing metabolites. These metabolites are successively oxidized, and the free energy of oxidation is conserved in the form of the reduced coenzymes FADH₂ and NADH. These reduced electron carriers can then be re-oxidized when they transfer electrons to the electron transport chain.
• Ketosis is a metabolic process whereby ketone bodies are used by the cell for energy (instead of using glucose). Cells often turn to ketosis as a source of energy when glucose levels are low; e.g. during starvation.
• Oxidative phosphorylation is the process where the energy stored in the relatively weak double bonds of O₂  is released in a controlled manner in the electron transport chain. Reducing equivalents such as NADPH, FADH₂ and NADH can be used to donate electrons to a series of redox reactions that take place in electron transport chain complexes. These redox reactions take place in enzyme complexes situated within the mitochondrial membrane. These redox reactions transfer electrons "down" the electron transport chain, which is coupled to the proton motive force. This difference in proton concentration between the mitochondrial matrix and inner membrane space is used to drive ATP synthesis via ATP synthase.
• Photosynthesis, another major bioenergetic process, is the metabolic pathway used by plants in which solar energy is used to synthesize glucose from carbon dioxide and water. This reaction takes place in the chloroplast. After glucose is synthesized, the plant cell can undergo photophosphorylation to produce ATP. Human Vitamin D production is another form of photosynthesis resulting in ATP production.