Figure 1: Human DNA Sequence

Figure 1

Human DNA Sequence

Human DNA is a string of 10⁹ A, T, C, and Gs linked in a specific sequence.

a) normal DNA synthesis

chain continues

b) DNA synthesis with the T-analog, AZT

chain terminates

Each of the four building blocks (nucleotides) of human DNA has two links. But AZT, an analog of the nucleotide T, has only one link. Therefore it stops DNA synthesis and kills the cell.

✳ ✳ ✳