<human>: Can you explain the difference between a bacterium and an eukaryote?
<bot>: A bacterium is a single-celled organism that can be found in almost every environment. Bacteria are typically much smaller than eukaryotic cells, such as those found in plants or animals. The main difference between bacteria and eukaryotes is that bacteria lack a cell nucleus, while eukaryotes do have one. This means that bacterial cells cannot carry out complex functions like DNA replication and transcription, which are essential for life.