Certain classes of drugs target the enzyme responsible for relaxing DNA supercoiling ahead of the replication bubble. By preventing this enzyme from reducing the strain, the DNA often experiences random breaks and fragments, ultimately killing the cell. Which enzyme is being targeted by this type of drug?

The enzyme being targeted by this type of drug is DNA topoisomerase or DNA gyrase.

Explanation: Replication requires not just a single DNA polymerase but different enzymes and proteins, each performing a specific task. DNA helicase separates the two parental DNA strands that act as templates in replication by moving along the DNA and separating the strand using chemical energy from ATP. DNA topoisomerase or DNA gyrase relieves the torsional strain or topological stress generated by DNA unwinding. DNA-binding proteins binds and stabilizes the separated single-stranded DNA. Primase synthesizes the short segments of RNA (RNA primers) which must be present on the template before DNA polymerase can begin to synthesize DNA.

the correct answer is b

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.