Metabolism and Nutrition

Overview of Metabolism

Metabolism encompasses all the chemical reactions that occur within the body to maintain life. These reactions are essential for energy production, growth, and cellular repair.

• Metabolism: The sum of the body's chemical reactions.

• Basic processes include:

  • Capturing energy from the chemical bonds of nutrients to produce Adenosine Triphosphate (ATP).

  • Carrying out synthesis reactions (Anabolism).

  • Breaking down macromolecules into monomers (Catabolism).

  • Converting one type of chemical into another.

Phases of Metabolism: Catabolism and Anabolism

Metabolism is divided into two main phases: catabolism and anabolism, each with distinct roles in cellular function.

Catabolism

• Breaks down nutrients (polymers) into smaller parts (monomers).

• Releases energy for ATP production.

• Cells use three types of nutrient monomers:

  • Glucose: Preferred fuel for many cells.

  • Fatty Acids

  • Amino Acids

• Catabolic reactions are generally exergonic (release energy).

Anabolism

• Monomers are combined to make macromolecules.

• Cells build proteins, nucleic acids, carbohydrates, lipids, and other macromolecules.

• Requires energy input, usually from ATP.

• Anabolic reactions are generally endergonic (require energy input).

Example: The synthesis of proteins from amino acids is an anabolic process that requires energy.

Energy Requirements of Metabolic Reactions

Metabolic reactions are classified based on their energy requirements:

• Exergonic Reactions: Reactions that release energy. Catabolic reactions are typically exergonic.

• Endergonic Reactions: Reactions that require an input of energy. Anabolic reactions are usually endergonic.

Key Terms:

• ATP (Adenosine Triphosphate): The primary energy carrier in cells.

• Polymer: A large molecule composed of repeating subunits (monomers).

• Monomer: A small molecule that can join with others to form a polymer.

Additional info: In cellular metabolism, the energy released from catabolic reactions is often used to drive anabolic reactions, maintaining the cell's energy balance.