Whom should you thank for the gift of life, the Enzyme or God, choice rest with you (Part – II):

Metabolism is Bio-Economics of energy

This article is part two of the article posted on February 13, 2019.

Metabolic processes of life are analogous to finance allocation and management. In order to carry out vital functions and processes growth, reproduction, respiration and transport, cell needs energy just as we require money/ currency for development of any project.

The term metabolism encompasses or all Bio-chemical processes which the cell must undertake so that it continues to carry its essential functions. One usually energy is produced when complex molecule are broken into simple ones is called Catabolism. For Ex. A sugar molecule breaking into simpler glucose molecule. Reaction in opposite direction that are needed by the body to sustain life i.e making of complex molecule like proteins ‘millions of them in a body’ from simpler one is called Anabolism and it requires an free energy (energy available for Bio-chemical work) as input. It is through anabolism that a cell synthesizes the complex molecule it needs.

Metabolic pathway

Pathway is route or a way of achieving a specified result formed by a long chain of bio-chemical events where the chemical products of each step becomes the substrate for the next step. A biological pathway is a series of interactions among molecules in a cell that leads to a certain product or a change in a cell. Such a pathway can trigger the assembly of new molecules, such as a fat or protein. Some of the most common biological pathways are involved in Metabolism, the regulation of gene expression and the transmission of signals. (Topic to be taken up in later article)

A metabolic pathway is a linked series of chemical reactions occurring within a cell. The two pathways complement each other in that the energy released from one is used by the other.

In biochemical reactions molecules or substrates, such as sugar converts into different, more readily usable materials for cell. These reactions occurs inside of a cell, where enzymes (protein molecule), break down or build up molecules. The reactant, product and intermediates of the enzymatic reaction are known as metabolites, which are modified by a sequence of chemical reactions catalyzed by enzymes.

There is a very large number of metabolic pathways (aerobic and anaerobic). In humans, the most important metabolic pathways are:

Glycolysis – glucose oxidation in order to obtain ATP

Citric acid cycle (kreb’s cycle) – Acetyle CO-A oxidation in order to obtain GTP and valuable intermediate

Oxidative phosphorylation – disposal of the electron released by glycolysis and citric acid cycle. Much of energy released in this process can be stored as ATP.

Pentose phosphate pathway – synthesis of pentoses and release of the reducing power needed for anabolic reaction.

Urea cycle – disposal of ammonium ion into less toxic forms.

Fatty acid beta oxidation – fatty acids breakdown into acetyle CO – A, to be used by the kreb’s cycle.

Gluconeogenesis – glucose synthesis from smaller precursor, to be used by brain.

(for those interested in details of these pathway consult any standard biochemistry textbook)

ATP (Adenosine tri phosphate)

ATP molecule acts as a energy bank i.e energy is deposited into it through catabolic reaction and deposited energy withdraw from it during anabolic reaction with the molecule acting as a energy bank.

When ATP is hydrolyzed and converted to Adenosine diphosphate (ADP), energy is released. This energy power all reactions that takes place inside the cell. ADP can also be converted back into ATP so, that the energy becomes available for other cellular reaction. ATP is produced through several different pathways phosphorylation is the pathway specific to plants and cyanobacteria. It is the creation of ATP from ADP using energy from sunlight, occur during photosynthesis. ATP also formed from the processes of cellular respiration in the Mitochondria of cell.

This article will continue as part three. Part three, which will deal with simple guidelines one should flow to stay healthy.