This model demonstrates the formation of the second half of DNA chain section that complements the first half in the process of DNA replication. Indicators of different shapes and colors represent the different nucleotides. The bottom window of the model contains information on indicator vs. nucleotide correlation (red stands for adenine, green is guanine, blue is thymine, and lilac is cytosine). |
Note that DNA-polymerase always builds the nucleotide that is complementary to the related nucleotide of the initial chain in the vacant spot of the forming chain. Once the fill-in process is complete, DNA-polymerase shifts forward by one nucleotide from the 3'- end of the initial chain to its 5'- end. Thus, synthesis of complementary chain takes place from its 5'- end towards 3'- end, since 5'- end of the complementary chain refers to 3'- end of the initial chain.