Bacteria do not "know" when it is time to split apart. Instead, they divide through a process called binary fission, which is triggered by specific environmental conditions and internal cellular mechanisms. Here's a general overview of how bacteria divide:

Cell Growth and DNA Replication: Bacteria grow and increase in size as they absorb nutrients from their environment. During this growth phase, the bacterial cell also replicates its DNA, creating two identical copies of the genetic material.

Initiation of Binary Fission: When the bacterium reaches a certain size and the environmental conditions are favorable (such as adequate nutrient availability), it initiates the process of binary fission.

Formation of the Septum: A septum, which is a dividing wall, begins to form across the center of the cell. The septum is composed of cell membrane and cell wall material.

Chromosome Segregation: The two replicated copies of the DNA (chromosomes) separate and move to opposite ends of the cell. Each chromosome becomes associated with one of the two forming daughter cells.

Completion of Cytokinesis: The septum formation continues until it completely divides the cell into two individual daughter cells. Each daughter cell receives one copy of the DNA and other essential cellular components.

Cell Maturation: Once the daughter cells are separated, they may continue to grow and mature. Depending on the species and environmental conditions, they may further divide or enter other phases of their life cycle.

It's important to note that the process of bacterial division is highly regulated and influenced by various factors such as nutrient availability, temperature, pH, and the presence of signaling molecules. Bacteria have evolved these intricate mechanisms to ensure proper cell division and survival under different environmental conditions.