"each cell from the same person will have different genomes"
Did you mean each cell will have different gene expression ?
I thought all the cells have the same nucleotide sequences barring maybe occasional mutations (like in cancer)
Did you mean each cell will have different gene expression ?
I thought all the cells have the same nucleotide sequences barring maybe occasional mutations (like in cancer)
Assuming each mutation is independent, etc, etc we get a back of the napkin via the binomial distribution with mean = n*p ~ 60 mutations per division.
However, that is for germline, somatic mutation rates are apparently 10-100x more more common: https://www.nature.com/articles/ncomms15183
These rates no doubt vary by cell type, environment, etc. I was actually thinking something like 1e-6 to 1e-10 mutations/bp/division.
Somatic mutations are just errors in genome duplication in somatic cell lines - i.e. not germ line. These accumulate over time and, yes, can be oncogenic. Many others simply have no consequence at all.
For many organisms, the germ line is 'sequestered' fairly early in development, in part to limit the number of replications needed, and thus errors that accumulate.