A number of antiviral drugs act by preventing viral DNA synthesis. These drugs are typically chemically similar to nucleotides with a modification. For example, the drug may contain all relevant components of a nucleotide, including a proper purine or pyrimidine base, but lack the 3' OH group. How would this modification allow this drug to prevent viral DNA synthesis

The DNA polymerase of the host cell can only add new nucleotides to the 3’ hydroxyl end of the growing DNA strand. When one of these nucleotide analogs which lack a 3’ hydroxyl end is added to the viral DNA strand being copied, the DNA polymerase can no longer continue transcription. These drugs effectively prevent DNA transcription.

Might need you in a few weeks c:

Proteins are the workhorses of the cell, controlling virtually every reaction within as well as providing structure and serving as signals to other cells. proteins are long chains of  amino acids  , and the exact sequence of the amino acids determines the final structure and function of the protein. instructions for that sequence are encoded in  genes  . to make a particular protein, a messenger ribonucleic acid (mrna) copy is made from the gene (in the process called  transcription  ), and the mrna is transported to the  ribosome  . protein synthesis, also called  translation  , begins when the two ribosomal subunits link onto the mrna. this step, called initiation, is followed by elongation, in which successive amino acids are added to the growing chain, brought in by transfer rnas (trnas). in this step, the ribosome reads the  nucleotides  of mrna three by three, in units called  codons  , and matches each to three nucleotides on the trna, called the anticodon. finally, during termination, the ribosome unbinds from the mrna, and the  amino acid  chain goes on to be processed and folded to make the final, functional protein