Q.Mitochondria and plastids have their own DNA (genetic material). What is known about their fate during nuclear division like mitosis?

Mitochondria and plastids, unlike the chromosomes in the nucleus, are not divided out through the spindle-and-kinetochore machinery of karyokinesis at all.

• Karyokinesis, the nuclear division part of mitosis, is specifically concerned with sharing out the duplicated nuclear chromosomes to the two daughter nuclei.
• The cytoplasmic organelles, such as the mitochondria and plastids, are instead shared out and distributed between the two daughter cells during cytokinesis, the separate step in which the cell body itself is divided. …

Mitosis is described as having two distinct components: karyokinesis, the division of the nucleus, and cytokinesis, the division of the cytoplasm that normally follows it. These two processes handle very different kinds of material.

• Karyokinesis is built entirely around faithfully separating the duplicated nuclear chromosomes — condensing them, aligning them at the metaphase plate via kinetochore attachments to spindle fibres, and pulling the sister chromatids apart to opposite poles. This machinery is specific to the chromosomes housed in the nucleus.
• Cytokinesis, by contrast, is the step in which the cell body itself splits so that each new nucleus ends up inside its own separate cell. It is specifically during this cytoplasmic division that the cell's organelles — such as the mitochondria and plastids — get shared out and distributed between the two daughter cells. …

Step 1 — Separate the two components of mitosis. Mitosis is made of karyokinesis (nuclear division) and cytokinesis (cytoplasmic division) — treat these as two separate 'jobs.'

Step 2 — Ask which job handles the chromosomes vs which handles everything else in the cytoplasm. Karyokinesis is built entirely around the duplicated nuclear chromosomes; it has no machinery for organelles. …