The simplest known circadian clock is that of the prokaryotic cyanobacteria. Recent research has demonstrated that the circadian clock of Synechococcus elongatus can be reconstituted in vitro with just the three proteins (KaiA, KaiB, KaiC) of their central oscillator. This clock has been shown to sustain a 22-hour rhythm over several days upon the addition of ATP. Previous explanations of the prokaryotic circadian timekeeper were dependent upon a DNA transcription/translation feedback mechanism.[citation needed] COUNT 5
QSN1 What has the simplest known circadian clock? ANS1 prokaryotic cyanobacteria QSN2 With how many proteins can the circadian clock of Synechococcus elongatus are needed to reproduce its effect? ANS2 three proteins QSN3 What type of feedback mechanism was previously thought to be needed to sustain the clock? ANS3 DNA QSN4 How long a rhythm were researchers able to sustain in the in vitro experiment? ANS4 22-hour QSN5 What were the only proteins necessary to the circadian timekeeper experiment? ANS5 KaiA, KaiB, KaiC