Answer:
Almost all of the cells have the exact same DNA.
Different genes are expressed in different types of cells.
Explanation:
All the cells of multicellular organisms are derived by repeated cell divisions in the zygote. This results in the presence of the same DNA in all the cells of a multicellular organism.
However, different cell types differ from each other as they produce different sets of mRNA and proteins. Irrespective of the presence of the same DNA, regulation of gene expression at the level of transcription and translation levels leads to the expression of different sets of mRNA and proteins.
Alternative splicing of the primary transcript, post-translational modification of proteins are some of the mechanisms that produce different mRNAs and proteins from the same DNA sequence.
Also, different cells respond to a stimulus differently. For example, liver and fat cells produce different proteins in response to their exposure to glucocorticoid hormones.
