Here's why:
* Differentiation: Somatic cells differentiate to perform specific functions. This differentiation process involves turning on and off specific genes, leading to variations in gene expression patterns.
* Mutations: During the lifetime of an individual, somatic cells can accumulate mutations in their DNA. These mutations are not inherited but can affect the function of the cell.
* Epigenetic modifications: Epigenetics refers to changes in gene expression that don't involve alterations in the DNA sequence. These changes, like methylation or histone modifications, can alter the accessibility of genes to the machinery that reads and transcribes them.
While the genome itself is identical, the epigenome, which encompasses all the epigenetic modifications, can differ significantly between cell types, leading to distinct patterns of gene expression.
In summary:
While all cells in the body contain the same DNA sequence, the active portion of that DNA (the genes that are expressed) can differ significantly between cell types. This variation in gene expression is what allows different cells to perform their specialized functions.
