Question

7. When biologists worked out the details of DNA replication in bacteria and eukaryotes, many researchers were surprised to discover that there are several different DNA polymerases, each with a different role. The machinery of replication seems enormously complex, and every piece seemed essential if the whole system was to function at all. Many people found it hard to imagine how such a complex system of interdependent parts could have evolved by natural selection. How does the discovery of organisms with only one DNA polymerase (such as Methanococcus jannashii) offer new insights into the evolution of replication?

Answer 1

For the process of replication each cell of species require the DNA polymerase enzymes. These are the essential enzymes for the polymerization of the nucleotides in the DNA strand's synthesis.

There are several kinds of polymerase for the replication in various species.

The prokaryotes contain DNA polymerase I, II, III.

The eukaryotes contain about 13 DNA polymerases out of which most important are DNA polymerase alpha, delta, epsilon.

They all act in a coordinated manner. Some have role of polymerization, some having the initiation role while some with elingation role. Some of them are for the correction if any error occurred.

So, if a species doesn't contain different enzymes for specific functions they are primitive in evolution race.

There are several chances of errors which can also lead to mutations.

But these are helpful in the study of replication processes as their replication is not much complex. So the roles of an enzyme are clear. While in the organism having complex system of DNA polymerase, the study is not easy as there are many enzymes and they may perform same function or even no known function.

Thanks.