Definition

1. Noun:
   • A metabolic pathway: The citric acid cycle is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins into carbon dioxide and chemical energy in the form of adenosine triphosphate (ATP).
   • A central part of cellular respiration: It is a crucial metabolic cycle that occurs in the mitochondria of cells, where it completes the breakdown of nutrients and provides precursors for various biosynthetic pathways.

Usage Examples

• Noun:
  • The citric acid cycle is also known as the Krebs cycle or the tricarboxylic acid (TCA) cycle.
  • Understanding the steps of the citric acid cycle is fundamental to biochemistry.
  • Energy production in the cell depends heavily on the efficient operation of the citric acid cycle.

Advanced Usage

• "to enter the citric acid cycle": Refers to the point where acetyl-CoA molecules begin the series of reactions.

  • Pyruvate is converted to acetyl-CoA before it can enter the citric acid cycle.

• "intermediates of the citric acid cycle": Refers to the molecules produced at each step of the cycle, which can be used for other cellular processes.

  • Some intermediates of the citric acid cycle are used in the synthesis of amino acids.

Variants and Related Words

• Krebs cycle (n): A common synonym for the citric acid cycle, named after Hans Krebs.

  • The Krebs cycle is a key component of aerobic respiration.

• Tricarboxylic acid (TCA) cycle (n): Another formal synonym for the citric acid cycle.

  • The TCA cycle occurs in the mitochondrial matrix.

Synonyms

• Krebs cycle: The most widely used synonym.
• Tricarboxylic acid cycle (TCA cycle): A more chemical term for the same process.

Related Phrases

• Citrate synthase: The enzyme that catalyzes the first reaction of the cycle.

  • Citrate synthase combines acetyl-CoA and oxaloacetate to form citrate.

• Oxidative phosphorylation: The process that follows the citric acid cycle to produce most of the cell's ATP.

  • The NADH and FADH2 produced in the citric acid cycle drive oxidative phosphorylation.

Noun

1. in all plants and animals: a series of enzymatic reactions in mitochondria involving oxidative metabolism of acetyl compounds to produce high-energy phosphate compounds that are the source of cellular energy