2.Molecular Biology A.Background DNA Molecules Every human cell contains the Cell same DNA (with the exception of mature red blood cells, Nucleus which have no nucleus). Each human cell (with the exception of reproductive cells, 3 which have half of the DNA)has 46 molecules of double- stranded DNA. ChromosomesDNA Molecules Every human cell contains the same DNA (with the exception of mature red blood cells, which have no nucleus). Each human cell (with the exception of reproductive cells, which have half of the DNA) has 46 molecules of double￾stranded DNA. 2. Molecular Biology A. Background