What happens in irradiated cells during cell division?

Answer 1

Irradiated cells will divide the same as they did before irradiation unless actively used genes were damaged and repaired incorrectly or unsuccessfully by the natural DNA repair mechanisms that cells possess. (Some genes like those that make the flagellum of a sperm cell, do not get used all the time or ever in some cells and therefore do not matter towards some cells' ability to function.)

Damaged genes responsible for vital, universal cell functions will be copied in their damaged states. If the cell survives this damage long enough to complete the split, the two resulting cells will contain the same damage. These cells will eventually fail to bulld the needed protein and all cells with the damaged gene will die, probably at about the same time as the cell division will have split the existing protein supply in half and cell growth after the division will produce still lower concentrations of the important protein in the full-size cell.

If the genes damaged by the irradiation produce proteins important in the division process itself, the division may proceed normally for the first division and then fail after that, leaving the cell unable to divide any further if the needed proteins are already in adequate supply to allow a limited number of divisions to complete.

When the supply of the necessary protein are depleted and mitosis cannot continue, depending on which genes responsible for mitosis structures were damaged, you will find the cell stuck at one of the stages of mitosis.

If this happens early, you may end up with a large, overgrown cell that simply fails to begin the split. Due to increased volume, this cell may suffer inefficient function as its maximum volume may produce longer transport times across the cell for needed materials and nutrient diffusion. It might live, but contribute less towards the purpose cells of its type have. It may also die due to the excessive volume producing harmful effects over an extended period that was never meant to occur over a long term.

After that, one of the earlier steps is compression of chromatin into Chromosomes. In DNA's compressed state, genes are not being read, as the enzyme responsible (transcriptionase) will be unable to connect to the DNA when compressed (try reading a newspaper when it's crumpled up). Unable to read the DNA, only existing RNA will be available to produce cellular proteins from. The comparatively unstable RNA molecules will decay in time leaving no mechanism to make vital proteins necessary for cell function. A cell stuck in a stage of mitosis where DNA is condensed into Chromosomes will die in a relatively short time.