Question

What is the average cell cycle span for a mammalian cell ?

Answer 1

Cell cycle is an ordered sequence of events that happens in a cell, for preparation of cell division, it is usually a four-stage process, in which the cell increase in size, copies its DNA, prepare to divide and cell division takes place in a sequence manner.

Complete answer:
The average cell cycle span for a mammalian cell is 24 hours.
- For the cell cycle to occur, events for cell division should start.
- Stimulation of cell division is done by special proteins, which are of 4 types, they are growth factors, growth factor receptors, signal transducers, and nuclear regulatory proteins.
- All the proteins act together and produce the cell signal, which reaches to the nucleus to turn on cell division.
- The events to stimulate signal includes, Growth factor binds to the receptor of the cell membrane, and after binding, this receptor is temporarily activated which stimulates the signal, and this signal reaches the nucleus and further activates the transcription genes, for proliferation.
- For the cell cycle, to progress properly, there are special proteins and checkpoint systems.
- The cell cycle occurs in a manner of G1 phase, where an increase in cell size occurs, and S-Phase where the synthesis of DNA occurs, and G2- Phase where preparation takes place and M phase where division takes place.
- A checkpoint occurs at the end of the G1 phase and at the beginning of the G2 phase.
- The stage G1, S, and G2 account for interphase.
- There is a production of stimulation or inhibitory signals, for the cell to enter the cell cycle and proceeds cell division.

Note: Total life span of the cell cycle is generally 24 hours, but out of which 1 hour of time is consumed by the G1 phase and S phase it takes 8 hours, and for G2 phase it is 4 hours, M phase it is 1 hour, and cell cycle repeated for every 30 minutes.