It's not quite accurate to say that certain organisms *don't* perform mitosis. Instead, it's more accurate to say that certain cell types within an organism might not undergo mitosis. Here's a breakdown:

* Most Eukaryotes: The vast majority of multicellular eukaryotic organisms, including plants, animals, fungi, and protists, use mitosis for growth, repair, and asexual reproduction.

* Exceptions:

* Mature nerve cells (neurons) and muscle cells: These are highly specialized cells that generally do not divide after they mature. This is why injuries to the brain or spinal cord are often permanent.

* Red blood cells: These cells lose their nucleus during development, making them unable to undergo mitosis.

* Gametes (sperm and egg cells): These cells are produced through a specialized process called meiosis, which involves two rounds of cell division.

* Prokaryotes: Prokaryotes (bacteria and archaea) do not undergo mitosis. They reproduce through a process called binary fission, where the single circular chromosome replicates and the cell divides into two identical daughter cells.

Important Note: Even within an organism, some cells might not be actively dividing at any given time. They might be in a resting phase (G0) of the cell cycle, but they still retain the potential to enter the cell cycle and undergo mitosis if needed.