FIGURE 24.03 Synthesis of DNA—Priming and Elongation
During normal DNA synthesis, DNA polymerase reads the template strand and makes a new complementary strand of DNA. To get DNA synthesis started, a short oligonucleotide primer must anneal to the 3' end of the template. DNA polymerase recognizes the 3' end of the primer and adds incoming nucleotides to the 3' end, hence synthesis occurs in a 5' to 3' direction.
3' ACGGCTATTA DNA CGCTGCAATGCTTCGGAAACA 5'
Dna polymerase adds nucleotides to end of primer
3' ACGGCTATTAACTGTCGGCG DNA CTTCGGAAACA 5'
FIGURE 24.04 Synthesis of
DNA poly merase links nucleotides via phosphodiester bonds. When adding another nucleotide, DNA polymerase breaks the bond between the first and second phosphates of the deoxynucleoside triphosphate. The incoming nucleotide is then joined to the free 3' hydroxyl of the growing DNA chain.
Growing DNA chain
Growing DNA chain will join at 3' position
will join at 3' position
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