Difference Between DNA Polymerase and RNA Polymerase

DNA Polymerase vs RNA Polymerase
 

These are two different enzymes responsible for different functions taking place in cellular level. Primarily the formation of DNA and RNA strands are regulated by these enzymes. This article intends to discuss the main differences of these extremely important enzymes for many processes of sustaining life.

DNA Polymerase

DNA polymerase enzyme starts its function during replication of DNA, at the step of arranging the relevant nucleotides to form hydrogen bonds between corresponding nitrogenous bases of the existing and new DNA strands. This enzyme becomes functional after the DNA double helix structure is dismantled or uncoiled by the exonuclease enzyme called DNA helicase. The polymerisation of the deoxyribonucleotides always starts from the 3’ end of the DNA strand. There are many types of DNA polymerases, and each type consists of a protein, which means that it contains a sequence of bases unique for a particular enzyme. There are about 900 – 1000 amino acids in human DNA polymerase chains. Usually, during the replication process, DNA polymerase is capable of copying the sequence of nitrogenous bases, so that it can produce more identical strands from one enzyme. The variation of this enzyme in different species is not much pronounced, as the catalytic subunits of the enzyme structure are almost the same in many species. However, based on those slight changes seven families of DNA polymerases named as A, B, C, D, X, Y, and RT have been identified. All these types have collectively 15 different enzymes among eukaryotes and 5 among prokaryotes.

RNA Polymerase

RNA polymerase is the main enzyme that catalyses the production of RNA strands. The templates of DNA nitrogenous base sequences are usually based to produce RNA, and this enzyme is capable of many functions. First, the particular part of the DNA strand (usually a gene) is uncoiled via breaking the hydrogen bonds between the corresponding bases of the opposing strands by RNA polymerase. After that, the copying of the base sequence by replacing uracil for thymine takes place from the 3’ end to 5’ end of the DNA strand. The starting point of the RNA polymerisation of the DNA strand is called the promoter while the completing end is known as the terminator. Since this enzyme forms the strand using ribonucleotides, the term RNA polymerase is used to refer. RNA polymerase can produce an array of products including messenger RNA, ribosomal RNA, transfer RNA, micro RNA, and ribozyme or catalytic RNA. Since RNA polymerase is capable of unwinding the DNA strand, it does not require another enzyme to dismantle the double helix structure. In bacteria, RNA polymerase is of few typesdenoted as α2, β, β’, and ω. Those bacterial RNA polymerases slightly differ to each otherstructurally and functionally. There are transcriptional cofactors those are bound to the RNA polymerase at different places to enhance the function, especially in some bacteria such as E. coli.