A clock is a term to describe the entire biological mechanism that regulates natural occurring rhythms in an organism. This mechanism occurs in a particular gene referred to as a clock gene. There are different clocks for different rhythms. The clock gene that controls when an ant lays an egg is different than the clock gene that controls when an ant searches for food. Furthermore, the gene that controls egg laying in the ant maybe very similar to the gene that controls egg laying in other insects.
Nature tends to be conservative.
There is increasing evidence that clock genes whether in an insect or a mammal regardless of its function are similar. This lends support to the theory that circadian rhythms and their clocks are wide spread throughout the body. DNA is the blueprint for the design and building of a living system such as a grasshopper, beetle, daisy or a human. Replication is the splitting of the two strands of DNA and each strand then acquiring a second strand to take the place of the strand that was removed. This is how DNA can make a copy of itself.