Question

Why is gap repair synthesis needed during HIV DNA integration?

Short answer

Gap repair synthesis is needed during HIV DNA integration to mend the 'gaps' left at each end of the inserted viral DNA sequence. It ensures successful incorporation of the viral DNA into the host genome, a vital step for the virus's replication.

Step-by-step solution

Understanding HIV's Replication Process

HIV, or the Human Immunodeficiency Virus, is a type of retrovirus. Retroviruses replicate by integrating a DNA copy of their genome into the host cell's DNA. This process is catalyzed by the viral enzyme integrase.

HIV DNA Integration

After the virus's RNA genome is reverse-transcribed into DNA, this viral DNA needs to be integrated into the host's genome for the virus to replicate. The enzyme integrase cleaves a few nucleotides from each 3' end of the viral DNA and facilitates its insertion into the host cell's DNA molecule. This results in 'gaps' between the ends of the integrated viral DNA and the host DNA.

Need for Gap Repair Synthesis

Gap repair synthesis is needed to fill these gaps. This process involves cellular enzymes that repair the break in the host DNA, essentially 'gluing' the viral and host DNA together. Without gap repair synthesis, the integration process is incomplete, and the virus cannot successfully replicate within the host cell. This repair process is essential for the continuity of the DNA molecule as well.