I want to understand genetic mutation specially in the context of multicellular organisms like humans. I studied biology only till high school and I can’t fully understand wikipedia pages on this subject.
I know that genetic material is in chromosomes inside the nucleus of a cell. When that cell multiplies, the chromosomes too generates a copy of themselves and both child cells get one set of the chromosomes.
I would like to know:
Does genetic mutation mean an error in chromosome generation at fission stage or will it occur later in the life of the cell?
Multicellular organisms begin their life from a single cell (zygote). Under normal circumstances, every cell that grows from this single cell should have the same genetic material. Can genetic mutation eventually result in us having different genetic material in cells of different parts of our body? For example, when only a part of our body gets exposed to radiation.
If answer to question 2 is yes, which genetic material will control the behaviour of the cells? Let’s say, for example, that the genetic material of cells in our stomach favour high growth rate of hair but the cells in the scalp themselves do not have that particular gene. What will be the result?