Infectious Diseases > Fluoroquinolones: Mechanisms of Action and Resistance

Audience: Healthcare providers

Animation Description:
In this animation, we demonstrate the biology of DNA replication leading to bacterial cell division in a gram positive bacterium, such as S. pneumoniae. The DNA is shown as a circular double strand within the bacterial cell. Like the DNA of all living organisms, it contains the unique genetic code for all of the proteins required for bacterial survival. Bacteria replicate by a process known as binary fission whereby one bacterium separates into 2 new daughter cells. However, before this can occur, the bacterium must make an identical copy of its complete circular DNA. DNA replication requires that the two strands of DNA separate so that the genetic code of the bacterium can be read and a new complimentary strand can be created for each of the original strands. To accomplish this, various enzymes known as helicases break the hydrogen bonds between the bases in the two DNA strands, unwind the strands from each other, and stabilize the exposed single strands, preventing them from joining back together. The points at which the two strands of DNA separate to allow replication of DNA are known as replication forks. The enzymes DNA polymerase then move along each strand of DNA, behind each replication fork synthesizing new DNA strands (in red) complementary to the original ones. As the replication forks move forward, positive superhelical twists in the DNA begin to accumulate ahead of them. In order for ...