Here's why:
* DNA is the blueprint: DNA contains the genetic instructions for building and maintaining an organism.
* Cell division: New cells are created through cell division, where the DNA is replicated and passed on to the daughter cells. This ensures that every cell receives a complete copy of the organism's DNA.
* Specialization: While all cells have the same DNA, they express different sets of genes, leading to different functions and specialized cells like nerve cells, muscle cells, and skin cells.
However, there are some exceptions:
* Mutations: Occasionally, mutations can occur during DNA replication, resulting in slight differences in DNA between cells.
* Immune cells: Immune cells undergo a process called "somatic recombination," where their DNA is deliberately rearranged to create a vast diversity of antibodies.
In summary: While all cells in a multicellular organism have the same fundamental DNA, there are some exceptions and variations due to mutations and specialized processes like immune cell development.
