How does the concept of a circle relate to cyclins?

The detail answer is given in the explanation section.

Explanation:

Cyclins are among the most essential core cell cycle regulators. Cyclins are a group of related proteins.  There are four basic types found in humans and most other eukaryotes. Each cyclin is correlated with a particular condition, transition, or set of stages in the cell cycle, and thus, they help to make the events of that phase or period.

A typical cyclin is present at the lower levels for most of the cycle but increases sharply at the stage where it's required.

meteorologists would compare a new weather map with one 24 h old to see how fast a front is moving.

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands