Final answer:
Clock genes and their products establish rhythms through cyclic transcriptional regulation in a 24-hour cycle.
Step-by-step explanation:
Circadian rhythms are biological rhythms that occur in a 24-hour cycle. These rhythms are controlled by a structure called the biological clock, located in a gland at the base of the brain. Clock genes and their products play a crucial role in establishing and regulating these rhythms through cyclic transcriptional regulation. They do not have a face and hands or interrupt natural circadian rhythms. Instead, clock genes turn 'on' once every 24 hours, establishing the rhythmic patterns.