One-celled organisms, also known as single-celled organisms, can reproduce by the process of binary fission.

Here's how it works:

1. Replication of DNA: The organism's single chromosome replicates, creating two identical copies.

2. Cell Growth: The cell grows in size, and the two copies of DNA move to opposite ends of the cell.

3. Cytoplasm Division: The cell membrane pinches inward, dividing the cytoplasm and eventually separating the two DNA copies into two distinct cells.

This process results in two identical daughter cells from a single parent cell.