Fundamentals of Molecular Biology - V.I. Rezyapkin 2009

Genome Organization
DNA-Containing Viruses

Viral DNA genomes can be either single-stranded or double-stranded, circular or linear:

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Linear double-stranded genomes do not have "plain" ends:

a) the ends may feature direct terminal repeats;

b) the ends can be sticky;

c) some Viruses have inverted repeats;

d) virus-specific Proteins may be attached to the 5’-end;

e) complementary strands can be covalently linked to each other.

DNA genome Replication poses certain challenges due to the fact that DNA Synthesis proceeds in the 5’- to 3’-direction and DNA polymerase requires a primer. A problem arises in filling the gap left by the removal of the RNA primer (Fig. 11.1). DNA polymerase cannot fill this gap because it is only capable of extending a DNA chain in the 5’- to 3’-direction.

Fig. 11.1. DNA polymerase is unable to fill the gap resulting from primer removal.

Viruses employ a variety of clever mechanisms to overcome this problem.



Last update: 12/08/2026

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