Cells within an organism can be very different from one another. For example, human red blood cells are filled with hemoglobin, are shaped like biconcave discs, lack a cell nucleus, and cannot synthesize proteins. Human muscle cells, on the other hand, are cylindrical in shape and have multiple nuclei.
Cell specialization in the human body is usually due to
A.
radiation by high energy photons that mutates the cells of the body into different shapes.
B.
different cells within the human body containing different, unique DNA sequences.
C.
mistakes that occur during DNA replication that result in framework mutations in the cells.
D.
different cells within the human body exhibiting different patterns of gene expression.