# Cell cycle analysis

### From OpenWetWare

**Cell cycle analysis of Escherichia coli cells**

C period = the time for a round of chromosome replication

D period = the time between the end of a round of chromosome replication and cell division

- Determination of initiation age (a
_{i}) and C+D:

From flow cytometry analysis of cells treated with rifampicin and cephalexin (run-out histogram) the proportions of cells that had not initiated replication at the time of drug action (4-origin-cells, streaked) and cells that had initiated (8-origin-cells) can be estimated.The initiation age (a_{i}) can be found from the theoretical age distribution described by this formula,

**F = 2 - 2 ^{((τ-ai)/τ)}**

where F is the fraction of cells that had not initiated and τ is the generation time, or from the estimated graph of the theoretical age distribution (streaked portion).

The C+D period is estimated from the initiation age (a_{i}), the generation time (τ) and the number of generations spanned per cell cycle.

Example:

4-origin-cells: 23 %

Generation time (τ): 27 min

Initiation age (a_{i}): 5 min