EVERYDAY SCIENCE

Detailed explanation-1: -Enzymes that regulate DNA supercoiling are known as ‘topoisomerases’. These enzymes are found in all cells, ranging from bacteria to humans, and alter the topological state of DNA by creating transient breaks in the sugar–phosphate backbone.

Detailed explanation-2: -DNA topoisomerases solve the topological problems associated with DNA replication, transcription, recombination, and chromatin remodeling by introducing temporary single-or double-strand breaks in the DNA.

Detailed explanation-3: -Abstract. Two DNA topoisomerases control the level of negative supercoiling in bacterial cells. DNA gyrase introduces supercoils, and DNA topoisomerase I prevents supercoiling from reaching unacceptably high levels.

Detailed explanation-4: -Topoisomerases play critical roles in DNA replication, transcription, and chromosome structure by altering the topological state of DNA, . These enzymes are capable of relaxing supercoiled DNA and of decatenating interlocked DNA (Fig. 3.3. 1).