Introduction to Metabolism | Catabolism Vs Anabolism | Biochemistry

Introduction to Metabolism

In this section, the speaker introduces metabolism and explains its definition. They also discuss how different pathways intersect with each other to form an integrated network of chemical reactions.

Metabolism Definition

• Metabolism refers to the sum of all chemical reactions taking place in a living organism.

• The product of one reaction serves as the substrate for the next reaction.

• Different pathways can intersect with one pathway, forming an integrated network of chemical reactions.

Two Purposes of Metabolism

• Metabolism generates energy to drive all vital functions in a living organism.

• It synthesizes biological molecules.

Catabolic Pathways

• Catabolic pathways are responsible for degrading complex molecules into building blocks.

• Proteins are broken down into amino acids, carbohydrates into monosaccharides, and fats into glycerol and fatty acids.

• Building blocks are subsequently degraded into a common product called acetyl CoA.

Anabolic Pathways

• Anabolic pathways synthesize complex molecules using precursor molecules provided by catabolic pathways.

• These pathways consume energy and are considered energy-requiring pathways.

Catabolic and Anabolic Pathways

In this section, the speaker explains the differences between catabolic and anabolic pathways. Catabolic pathways break down complex molecules into smaller ones to release energy, while anabolic pathways combine small molecules to form complex ones and require energy.

Catabolic Pathways

• Catabolic pathways are responsible for capturing chemical energy in the form of ATP.

• These pathways are oxidative, meaning they break down covalent bonds to release energy in the form of carbon dioxide and water.

• The reactions in catabolic pathways are exergonic, resulting in a net loss of energy.

• Coenzymes like NAD+ are required for these reactions.

Anabolic Pathways

• Anabolic pathways combine small molecules like amino acids, fatty acids, and monosaccharides to form complex molecules like proteins, lipids, and polysaccharides.

• These reactions require energy and are endergonic.

• Chemical reduction is involved in these reactions.

• NADPH is required as a reducing power source.

Comparison of Catabolic and Anabolic Pathways

• Complex molecules like proteins, carbohydrates, and lipids are broken down into building blocks by catabolism. These building blocks are then oxidized into carbon dioxide, water, and ammonia. This process releases free energy that is captured as ATP or reducing power.

• Anabolic pathways use precursor molecules provided by catabolism to synthesize complex molecules. These reactions require energy and involve chemical reduction.

Anabolic and Catabolic Reactions

In this section, we will learn about anabolic and catabolic reactions.

Anabolic Pathway

• Anabolic pathway is a reductive reaction that converts precursor molecules into complex molecules.

• It is an endergonic reaction where there is a gain of energy.

• The complex molecules produced are energy-rich fuel molecules.

• Anabolic reactions have a net gain of energy.

Catabolic Pathway

• Catabolic reactions are exergonic in nature.

• They break down complex molecules into simpler ones.

• These reactions release energy in the form of ATP or heat.

This section provides information on the difference between anabolic and catabolic pathways.