If each cell ( most cells) contain the same amount of chromosomes/dna material, how does differentiation work?

i.e., how does a skin cell replicate and express a certain part of the DNA compared to a heart cell when ALL the cells contain the same DNA. As in, how does each cell know which part of the DNA they need to copy and express?





And if a person has a disorder because of a genetic mutation that is inherted, does every cell in the body ( skin cells, heart cells etc) all display the mutation in their chromosomes/dna?

If each cell ( most cells) contain the same amount of chromosomes/dna material, how does differentiation work?
Like most other developmental processes, differentiation is controlled by genes, the genetic instructions encoded in the DNA of every cell. Genes instruct each cell how and when to build the proteins that allow it to create the structures, and ultimately perform the functions, specific to its type of cell.





Every nucleus of every cell has the same set of genes. A heart cell nucleus contains skin cell genes, as well as the genes that instruct stomach cells how to absorb nutrients. This suggests that in order for cells to differentiate -- to become different from one another -- certain genes must somehow be activated, while others remain inactive. There is no evidence that genes normally are lost during most developmental processes.


Epigenetic changes are believed to play a role in cellular differentiation. They refer to reversible, heritable changes in gene regulation that occur without a change in DNA sequence (genotype). These changes may be induced spontaneously, in response to environmental factors, or in response to the presence of a particular allele. pecific epigenetic processes of interest include paramutation, bookmarking, imprinting, gene silencing, X chromosome inactivation, position effect, reprogramming, transvection, maternal effects, regulation of histone modifications and heterochromatin. Modification of DNA also affects transcriptional output. Notably, many cytosines in eukaryotic DNA are methylated to 5-methylcytosine, particularly at CpG sites. The number and pattern of such methylated cytosines influences the functional state of associated genes: low levels of methylation correspond to high potential activity while high levels correspond to low activity. DNA methylation frequently occurs in repeated sequences, and may help to suppress 'junk DNA.