What is the definition of a dominant trait in biology? What is the difference between biology and AP biology? What is the difference between molecular biology and cell biology?
DNA gyrase, often referred to simply as gyrase, is an enzyme that relieves strain while double-strand DNA is being unwound by helicase. It is also known as DNA topoisomerase II. This causes negative supercoiling of the DNA. Bacterial DNA gyrase is the target of many antibiotics, including nalidixic acid, novobiocin, and ciprofloxacin.
After transformation, we challenge the bacteria with an antibiotic (such as ampicillin). If the E. coli have taken up and expressed an ampicillin resistance gene on a plasmid, they will live-otherwise they will die. This process is called selection, because we are selecting which bacteria may survive.ince a plasmid is (by definition) an extrachromosomal element, it cannot make use of any origin of DNA replication in a chromosome. That is, DNA synthesis within (i.e. copying of) a plasmid depends on its having an origin of DNA synthesis of its own.