How is tthe stability of DNA of the species ensured - Science - Heredity and Evolution

Question

How is tthe stability of DNA of the species ensured?

Ritika Goyal · Accepted Answer

DNA is the hereditary material of all the organisms So, it is
necessary for the organisms to ensure DNA stability to maintain
their species integrity Nature follows various methods to ensure
that DNA remains stable for a particular species with very few
minor variations (which are necessary for evolution) Some of these
are:
1) DNA replication is highly efficient process:
DNA polymerase, the enzyme which carries out DNA replication, is a
very efficient molecule with a very low error rate It has
proof-reading ability; it checks each and every base after addition
and removes it, if a wrong base is added So, it ensures that the
daughter DNA formed is exact replica of the parent DNA Hence helps
in stabilizing the DNA of the organism
2) Cell cycle stops if DNA is damaged: If due
to any reasons the DNA of a particular cell is damaged then the
cell cycle stops at that phase and the cell does not replicate
further and dies So, this ensures that unstable DNA or modified or
damaged DNA is not passed onto other cells
3) Chromosomal number is maintained during
reproduction To ensure that all the individuals of a
species have same number of chromosomes, the chromosomal number is
maintained during reproduction

Asexual reproduction : here the parent cell reproduces to form
exact replica of itself So, chromosomal number is maintained as
both the parent and daughter cells have same number of
chromosomes
Sexual reproduction : It involves fusion of two kinds of
gametes to form the offspring Hence to maintain a stable
chromosomal number, the number of chromosomes is halved during the
formation of gametes So, on fusion of two gametes we get the same
chromosomal number as that of the parent

So, these ensure that the chromosomal number or the DNA of an
organism is stable