Life's 24-hour clock: molecular control of circadian rhythms in animal cells

Trends Biochem Sci. 2000 Dec;25(12):601-6. doi: 10.1016/s0968-0004(00)01695-9.


Our sleep-wake cycles and many other approximately 24-hour rhythms of behavior and physiology persist in the absence of environmental cues. Genetic and biochemical studies have shown that such rhythms are controlled by internal molecular clocks. These are assembled from the cycling RNA and protein products of a small group of genes that are conserved throughout the animal kingdom.

Publication types

  • Review

MeSH terms

  • Animals
  • Behavior, Animal / physiology*
  • Circadian Rhythm / physiology*
  • Darkness
  • Drosophila / genetics*
  • Drosophila Proteins*
  • Insect Proteins / genetics
  • Insect Proteins / metabolism
  • Mammals / genetics
  • Mammals / metabolism
  • Mutation
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Period Circadian Proteins


  • Drosophila Proteins
  • Insect Proteins
  • Nuclear Proteins
  • PER protein, Drosophila
  • Period Circadian Proteins
  • tim protein, Drosophila