B. The levels of unbound cyclin E are at their lowest when the cell transitions into the S phase. Cell reproduction operates cyclically, governed by the specific needs of the cell. For mitosis, the transition from G1 to S to G2 to M is overseen by proteins like cyclins. In particular, passing from G1 to S requires cdK2. Cyclins are synthesized and degraded continuously throughout the cell cycle.
The progression of biology outlines the evolution of life studies from ancient eras to contemporary times.
Mary initially saw a doctor who wasn't trained in drawing blood or taking x-rays. She subsequently visited a different place that specializes in those procedures.
