Q. During DNA replication, when unwinding of the interwined double helix occurs the enzymes that can break and reseal one strand are called

 1474  208 Molecular Basis of Inheritance Report Error

Solution:

This enzymes change the way in which DNA is packaged in living cells by altering the degree of supercoiling of the DNA molecules. For example DNA gyrase, a topoisomerase found in E.coli, introduces negative supercoiling by breaking both strands of DNA double helix and passing another stretch of the double helix through the gap, which is then sealed. This creates a twist in the circular DNA of the bacterial chromosome. Other topoisomerases can remove supercoiling by introducing a temporary break in one DNA strand and passing the other through it.