Microbial Metabolism: Chemical Reactions and Pathways

Microbial Metabolism

Introduction to Metabolism

Metabolism refers to the collection of controlled biochemical reactions that take place within a microbe. The ultimate function of metabolism is to enable the organism to reproduce and sustain life.

• Metabolism: The sum of all chemical reactions in a cell.

• These reactions are highly regulated and interconnected.

Eight Elementary Statements Guiding Metabolic Processes

Microbial metabolism is governed by a series of fundamental principles that ensure the cell's survival and reproduction.

• Every cell acquires nutrients.

• Metabolism requires energy, which is obtained from light or the catabolism of nutrients.

• Energy is stored in the form of adenosine triphosphate (ATP).

• Cells catabolize nutrients to form precursor metabolites.

• Precursor metabolites, ATP, and enzymes are used in anabolic reactions.

• Enzymes and ATP facilitate the formation of macromolecules.

• Cells grow by assembling macromolecules.

• Cells reproduce after doubling in size.

Catabolism and Anabolism

Major Classes of Metabolic Reactions

Metabolic reactions are divided into two main categories: catabolic and anabolic pathways.

• Catabolic pathways:

  • Break larger molecules into smaller products.

  • Exergonic: Release energy.

• Anabolic pathways:

  • Synthesize large molecules from the smaller products of catabolism.

  • Endergonic: Require more energy than they release.

Overview of Catabolic and Anabolic Reactions

Catabolic and anabolic reactions are interconnected. The energy released from catabolic reactions is stored as ATP and used to drive anabolic reactions.

• Catabolism provides precursor metabolites and energy for anabolism.

• Anabolism uses these precursors and energy to build macromolecules necessary for cell structure and function.

Diagram: Metabolism is composed of catabolic and anabolic reactions

This diagram illustrates the flow of energy and materials in a cell:

• Catabolic reactions break down nutrients, releasing energy (some lost as heat) and generating ATP and precursor metabolites.

• Anabolic reactions use ATP and precursor metabolites to build macromolecules and cellular structures.

• Energy is stored in molecules like carbohydrates and lipids, and used for cellular processes such as growth and division.

Example: The breakdown of glucose during glycolysis (catabolism) provides ATP and building blocks for the synthesis of proteins and nucleic acids (anabolism).

Additional info: Later sections would likely cover specific metabolic pathways, enzyme function, and regulation, as well as the integration of catabolic and anabolic processes in microbial cells.