Helicase: the DNA separator
Prelims:
Science
& Technology
Mains:
GS
Paper III: Science & Technology – developments and their applications, GS
Paper III: Biotechnology and developments in genetics
Current relevance:
A recent study published in Nature Communications has examined how cells ensure that DNA replication begins only at the appropriate time, finding that a molecular safety mechanism keeps the DNA-copying machinery inactive until a chemical signal releases it.
Highlights:
About Helicase:
1.
Helicase
is an enzyme that unwinds and separates the two strands of DNA, allowing
the genetic information stored in them to be copied.
2.
DNA
normally exists as a double helix, consisting of two long strands held
together by bonds between bases.
3.
During
cell division, these strands must be separated so that the cell can produce
a copy of its DNA.
4.
Helicase
therefore plays a crucial role in initiating and facilitating DNA
replication.
How Does Helicase Work:
1.
Helicase
first attaches to a particular region of DNA and then moves along the
DNA molecule.
2.
It
uses energy derived from ATP, the cell's main chemical energy source, to
change its shape and force the two DNA strands apart.
3.
As
helicase moves, the bonds between the bases of the two strands are broken,
exposing the individual DNA strands.
4.
This
produces a Y-shaped region called the replication fork, similar to the
opening created when a zipper separates.
5.
Each
exposed strand can subsequently act as a template for the formation of a new
complementary DNA strand.
Role of Topoisomerases
& Regulation:
1.
As
helicase moves along DNA, the molecule tends to become increasingly twisted
ahead of the replication fork.
2.
Enzymes
called topoisomerases relieve this twisting, preventing DNA from
becoming tangled or breaking.
3.
Once
the strands are separated, other components of the DNA replication machinery
use them as templates to produce complementary strands.
4.
The
recent study found that cells also possess a molecular safety mechanism
that keeps the DNA-copying machinery inactive until an appropriate chemical
signal allows replication to begin.
Source: THE HINDU - https://www.pressreader.com/india/the-hindu-chennai-9ww3/20260819/282394111285714?srsltid=AfmBOooVN66fHLuX3vE81AD5D3PXM-Ww_o4ApTGftd6jh52HSqKCokAO