Final answer:
The nucleic acid synthesis inhibition is used to 2) Treating viral infections and 3) Treating bacterial infections
Step-by-step explanation:
Antiviral drugs and antibiotics are used to treat viral and bacterial infections, respectively. Nucleic acid synthesis inhibition is one of the mechanisms by which these drugs work. For example, antiviral drugs called nucleoside analogs inhibit viral DNA replication by causing chain termination during replication. These drugs have increased affinity for viral DNA polymerase compared to host cell DNA polymerase. Similarly, antibiotics that inhibit bacterial nucleic acid synthesis, such as quinolones and rifampin, block DNA replication in bacteria and RNA polymerase activity, respectively.
Antiviral drugs, such as acyclovir, interfere with viral DNA replication. They are nucleoside analogs that resemble the normal building blocks of DNA. Once activated by a viral enzyme, they are incorporated into the growing DNA strand, leading to chain termination. These drugs are specific to virus-infected cells because they require viral enzymes for activation and have higher affinity for viral DNA polymerase compared to host cell DNA polymerase.
Antibiotics like quinolones and rifampin target bacterial nucleic acid synthesis. Quinolones, including nalidixic acid, inhibit the activity of bacterial DNA gyrase, which is essential for DNA replication in bacteria. This inhibition leads to the blocking of DNA replication. Rifampin, on the other hand, blocks RNA polymerase activity in bacteria. RNA polymerase in bacteria is structurally different from that in eukaryotes, which allows selective toxicity against bacteria. Therefore the correct answer is 2) Treating viral infections and 3) Treating bacterial infections