Basic Biochemical Principles

Basic Biochemical Principles

Catabolism: It is the process of breakdown of complex molecules (proteins, polysaccharides, lipids, etc.) to the simpler molecules (CO₂, NH₃ and H_2O), accompanied by the synthesis of ATP. ATP is frequently described as energy currency of the cells. It can be transported to those sites of the cell where it is utilized for various cellular functions.

Anabolism: It is the process of biosynthesis of complex molecules (proteins, polysaccharides, lipids, etc.) from the simple precursor molecules (Acetyl CoA, Amino acids, Glucose, etc.), accompanied by utilization of energy. Usually, ATP provides the energy for all the process.

Metabolism: The sum of catabolism and anabolism within the cells and tissues called metabolism

Anabolism

Small Molecules                                            Large Molecules

Catabolism

The term anabolism or catabolism is generally referred to metabolism. When the process of anabolism increased than catabolism, the growth of organism occurs. It happens in the period of immaturity. If the process is balance, there is no change in the tissue mass. This represents the normal maturity. When the process of catabolism increased than anabolism, mass of the tissues declines. It happens in the old age and in starvation period.

Pathways: In the cell, anabolism and catabolism rarely occur in a single step. These reactions are usually organized in multistep sequence called pathways. These pathways are called either anabolic pathways or catabolic pathways depending upon the ongoing process. Collectively, these pathways are called metabolic pathways.

Principal ingredients of our dietary food: We are heterotrophs and feed on others. We can synthesize our organic molecules only from other organic compounds that we obtained from autotrophs (plants). Principal ingredients of our dietary food are carbohydrates, fats, proteins etc.

Digestion of our dietary food occurs in three stages.

Stage 1: Digestion of complex dietary fuel to their monomer units, which absorb from the gut e.g.

i)                    Carbohydrates convert into their respective monosaccharide.

ii)                  Proteins convert into their respective amino acids.

iii)                Fats convert into their respective fatty acids.

Absorption of these monomer units occur in GIT

Stage 2: Conversion of monomer units into simple molecules within the cells.

Here, all monomer units include monosaccharides, amino acids and fatty acids converted into common breakdown product called Acetyl CoA.

Stage 3: Simple molecule like Acetyl CoA can either be catabolized to carbon dioxide and water or again anabolized to form the precursor monomer molecules. This stage also called amphibolic pathway.