Overview of Metabolism

Overview of Metabolism

• Metabolism involves chemical reactions in metabolic pathways coordinated by specific enzymes.

Catabolic and Anabolic Pathways

• Catabolic Pathways: Breakdown cellular components, exergonic process (releases energy).

• Anabolic Pathways: Synthesize cellular components, endergonic process (requires energy, coupled with exergonic reactions).

Energy and ATP Production

• ATP is produced through two methods:

  • Substrate-Level Phosphorylation: Direct transfer of phosphate from one molecule to another by an enzyme.

  • Chemiosmosis: Utilizes energy from an electrochemical gradient to convert ADP and inorganic phosphate (Pi) to ATP.

Redox Reactions

• Involves transfer of electrons:

  • Oxidation: Removal of electrons.

  • Reduction: Addition of electrons; if A is oxidized, B is reduced.

NADH Overview

• NADH (Nicotinamide adenine dinucleotide) serves as an energy intermediate, releasing substantial energy upon oxidation and donating electrons during synthesis reactions.

Anabolic Reactions

• Biosynthetic processes required for forming larger macromolecules or smaller non-dietary molecules, driven by energy inputs like NADH or ATP.

Regulation of Metabolic Pathways

• Gene Regulation: Controlling gene expression.

• Cellular Regulation: Influences from cell-signaling pathways, e.g., hormones.

• Biochemical Regulation: Involves feedback inhibition, where the end product inhibits earlier steps to prevent excess accumulation. The rate-limiting step, being the slowest in a pathway, has significant influence over the overall pathway flow.