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"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 sam

"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)

nonbel 9y ago
Mutation rates are high enough that we should expect at least a few every division. There are supposedly n~6e9 base pairs[1] and mutation rate is said to be p~1e-8 per bp per division[2]. 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. [1] https://en.wikipedia.org/wiki/Human_genome https://en.wikipedia.org/wiki/Human_genome [2] https://en.wikipedia.org/wiki/Mutation_rate https://en.wikipedia.org/wiki/Mutation_rate
- chrisamiller 9y ago
  Most estimates I'm familiar with are substantially lower than that - between 0.1 and 3 errors per cell division.
  - nonbel 9y ago
    Thanks, actually the wikipedia link was "per generation" and they assume ~ 100 divisions/mitoses per human generation. So it should be 1e-10 mutations/bp/division. However, that is for germline, somatic mutation rates are apparently 10-100x more more common: https://www.nature.com/articles/ncomms15183 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.
Obi_Juan_Kenobi 9y ago
There are somatic mutations (vs. germ line, which would be inherited). 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.

nonbel 9y ago

Mutation rates are high enough that we should expect at least a few every division. There are supposedly n~6e9 base pairs[1] and mutation rate is said to be p~1e-8 per bp per division[2]. 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. [1] https://en.wikipedia.org/wiki/Human_genome https://en.wikipedia.org/wiki/Human_genome [2] https://en.wikipedia.org/wiki/Mutation_rate https://en.wikipedia.org/wiki/Mutation_rate

chrisamiller 9y ago
Most estimates I'm familiar with are substantially lower than that - between 0.1 and 3 errors per cell division.
- nonbel 9y ago
  Thanks, actually the wikipedia link was "per generation" and they assume ~ 100 divisions/mitoses per human generation. So it should be 1e-10 mutations/bp/division. However, that is for germline, somatic mutation rates are apparently 10-100x more more common: https://www.nature.com/articles/ncomms15183 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.

Obi_Juan_Kenobi 9y ago

There are somatic mutations (vs. germ line, which would be inherited). 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.