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  • Writer's pictureNanoEntek

Cell Cycle Assay

Updated: Jan 2

In cell biology, cell cycle is one of the fundamental and basic topics to learn. The phases of cell cycle, which are interphase, mitosis and cytokinesis. To be more specific, interphase includes G1, S and G2 phases and mitosis.

Fig.1 Cell cycle

Brief Description of Each Phase

G1 phase

Cellular contents are duplicated

S phase

Synthesis phase where DNA is replicated of which 46 chromosomes are replicated by the cell

G2 phase

​Cells are preparing for division at mitosis


Cells are physically separated and form two identical daughter cells


A cell arrest or quiescence state where cells remain inactive. Cells in this phase either remain arrested or re-enter the cell cycle after stimulated

Cell Cycle Assay

The purpose of the cell cycle assay is to quantify the cells at various stages of the cycle and examine the frequency and timing of DNA duplication. The primary goal of cell cycle research is to get a deeper understanding of protein interactions and, moreover, signaling pathways, many of which are important in regulating progression through the cell cycle. This potentiality may lead to profound research into aging, biology, cancer, and the development of organisms. It may even involve the use of stem cells to treat damaged organs and body parts. As a result, research on the cell cycle is expanding its possibility for studying cancer and abnormality growth [1].

Depending on a treatment used and its duration of time treated to the cell sample, cell cycle graph will be shown differently.

Fig.2 Cell cycle graph

In non-synchronized* control cell sample, a graph shown in Fig. 2 is the standard form. Each peak or y-axis represents the cell population at specific phase whereas the x-axis implies the intensity of fluorescence.

*Cell synchronization is a process of bringing all cells at different stages involved in the cell cycle to the same phase. Synchronization is used to study the characteristics of cells or any specific events involved in each cell cycle phase.

Fig.3 Human cells typically takes 24 hours per cell cycle
Fig.3 The estimated time of human cell cycle

Typical time spent in each of the phase of a cell with a total cell cycle of 24 hours is as follows:


11 hours


8 hours


4 hours


1 hour

The Most Important Consideration in Cell Cycle

To emphasize, the most important factor to consider in cell cycle is the duration of chemical treatment applied to the cells for study.

For example, if you are to examine Substance A that will be treated to the cells,

- duration of Substance A treatment time

- the purpose of Substance A (e.g. activating one of the checkpoints, triggering re-entering into cell cycle, etc.)

- apoptosis occurrence, etc.

should be known in order to obtain cells at phase you want to study with.

To sum up, cell cycle is one of the essential ways of studying how cells proceed at specific phases which then leads to opportunities in understanding disease, cancer and even at broader aspect, the development of all organisms.


1. Nature News, Nature Publishing Group,,repair%20via%20stem%20cell%20therapies. Accessed 30 Nov. 2023.

Objective lens

4x , 10x , 20x

Channel type

Brightfield, GFP, RFP, DAPI

Vessel type

Well plate, flask, dish, slide

Incubator installation



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