Jmtoral

Biochemical Energy
Introduction to biochemical energy
Living things store energy mainly in the form of chemical bonds. Within the cells energy is constantly moved around from one large molecule to another. Energy required for all the process of cells is provided through biochemical energy i.e. ATP (Adenosine triphosphate). ATP is a adenine nucleotide which consists of ribose sugar, adeninenitrogenous base, and three phosphate group. The phosphate group is held together by high energy bonds. Hydrolysis of these bonds is release a great amount of energy, which can be used for endergonic reaction in cells.
Hydrolysis of ATP yields a phosphate group and ADP (Adenosine diphosphate) with release of energy and the reverse of ATP hydrolysis is a phosphorylation reaction. The three processproduction, transport, and utilization of biochemical energy also require the energy via ADP/ ATP inter conversion. As the energy required for all cellular activities is provided by ATP hydrolyses, ATP is also called as “energy currency of cell".
ADP is converted into ATP through two processes
1) Substrate-level phosphorylation: Substrate-level phosphorylation occurs in the cytoplasm
2)Chemiosmosis: Chemiosmosis occurs through electron transport chain that is embedded in a membrane. In eukaryotes this membrane is in either the mitochondrion or chloroplast. Mitochondria are also called as power house of the cells as most of the biochemical energy is produced in mitochondrion.
During photosynthetic process ATP is produced through cyclic and non-cyclic photo-phosphorylation reactions. Herelight energy is converted to produce biochemical energy.
The energy released when food molecules is broken down is used to reform the bonds between the phosphate groups to recreate ATP. The process by which ATP is produced is differently in anaerobic and aerobic organisms. More amount of energy can be released when oxygen is present than during aerobic reactions.
Glucose is the main source ofenergy for living organisms. In breaking down glucose, the energy present in the glucose molecule's chemical bonds is released and used by the cell to form ATP molecules. The process by which this occurs consists of several stages that include glycolysis, Krebs cycle, electron transport

ATP stands for adenosine-5'-triphosphate. It is comprised of an adenine ring, a ribose sugar, and threephosphate groups. ATP is often used for energy transfer in the cell. ATP synthase produces ATP from ADP or AMP + Pi. ATP has many uses. It is used as a coenzyme, in glycolysis, for example. ATP is also found in nucleic acids in the processes of DNA replication and transcription. In a neutral solution, ATP has negatively charged groups that allow it to chelate metals. Usually, Mg2+ stabilizes it.  Introduction
ATP is an unstable molecule which hydrolyzes to ADP and inorganic phosphate when it is in equilibrium with water. The high energy of this molecule comes from the two high-energy phosphate bonds. The bonds between phosphate molecules are called phosphoanhydride bonds. They are energy-rich and contain a ΔG of -30.5 kJ/mol.
Hydrolysis of ATP
Removing or adding one phosphate groupinterconverts ATP to ADP or ADP to AMP.
Breaking one phosphoanhydride bond releases 7.3 kcal/mol of energy. 
      ΔG = -30.5 kJ/mol
         ΔG = -61 kJ/mol
      ΔG = -61 kJ/mol
At pH 7,

Why is ATP hydrolysis an exergonic reaction?
1. The entropy, which is the level of disorder, of ADP is greater than that of ATP.  Therefore, due to thermodynamics, the reaction spontaneously occurs because itwants to be at a higher entropy level. Also, the Gibbs' free energy of ATP is higher than that of ADP. Naturally, molecules want to be at a lower energy state, so equilibrium is shifted towards ADP.
2.  Electrostatic repulsion of the four negative charges on the oxygens of the ATP molecule. Naturally, like charges repel and opposite charges attract. Therefore, if there are four negative charges...