Anabolism in Cellular Metabolism

Anabolism

• Anabolism is the metabolic process of building up or synthesizing compounds from simpler substances required by cells, requiring and storing energy.
• This process is endergonic, meaning it's not spontaneous and requires energy to progress the anabolic reaction.
• The complex molecules obtained are further used to store energy in the form of ATP (Adenosine Tri Phosphate).

Examples of Anabolic Processes

• Formation of disaccharides and water by combining simple sugars: C6 H12 O6 + C6H12O6 → C12 H22 O11 + H2O
• Formation of dipeptides by combining amino acids: NH2 CHRCOOH + NH2 CHRCOOH → NH2CHRCONHCHRCOOH + H 2 O
• Formation of lipids when glycerol reacts with fatty acids: CH2 OHCH(OH)CH2OH + C17H35COOH → CH2 OHCH(OH) CH2 OOCC17H35
• Process of photosynthesis to form glucose and oxygen: 6CO2 + 6H2 O → C6 H12 O6 + 6O2

Anabolic Hormones

• Insulin: promotes absorption of glucose
• Anabolic steroids: stimulate muscle growth
• Anaerobic exercise: helps in building muscle mass

Stages of Anabolism

• Production of precursors such as monosaccharides, nucleotides, amino acids, and isoprenoids
• Activation of the above-mentioned precursors into reactive forms with the help of energy from ATP
• Assemble the precursors to form complex molecules such as polysaccharides, nucleic acids, proteins, and lipids

Energy Sources for Anabolic Processes

• Autotrophs: formation of complex organic molecules from simple molecules like water and carbon dioxide with the help of sunlight as an energy source
• Heterotrophs: require complex substances such as amino acids and monosaccharides to produce complex molecules
• Photoheterotrophs and photoautotrophs: obtain energy from light
• Chemoheterotrophs and chemoautotrophs: get energy from inorganic oxidation reactions

Metabolism

• Metabolism refers to a series of chemical reactions that occur in a living organism to sustain life
• It involves two types of metabolic process: catabolism and anabolism

Catabolism

• The process involves the breakdown of large molecules such as polysaccharides, lipids, nucleic acids, and proteins into smaller units like monosaccharides, fatty acids, nucleotides, and amino acids, respectively
• The exact nature of catabolic reactions differs from organism to organism and can be classified based on their sources of energy and carbon

Stages of Catabolism

• Stage 1: Stage of Digestion (breakdown of large organic molecules into smaller components outside cells)
• Stage 2: Release of energy (broken-down molecules are taken up by cells and converted to yet smaller molecules, releasing energy)
• Stage 3: Energy Stored (released energy is stored by reducing the coenzyme nicotinamide adenine dinucleotide into NADH)

DNA Synthesis

• DNA is a macromolecule made up of smaller molecules known as nucleic acids
• DNA synthesis takes place in the nucleus of the cell before cell division, involving unzipping the double-stranded DNA, attaching new matching nucleotides to each strand to form two new strands