* DNA polymerase
• DNA polymerase is an enzyme that synthesizes the double-stranded DNA molecule.
• Molecular weight of DNA polymerase is 400 k Dalton.
• DNA polymerase's mechanism is during DNA replication where by it synthesizes new DNA strands
• DNA polymerase contains 10 subunits.
• The DNA polymerase replication mechanism is initiated by a short DNA/RNA primer
• DNA polymerase inserts nucleotide bases after finding the free 3' OH group end by the assistance of the primer-synthesizer, primase enzyme
• DNA polymerase adds deoxy Nucleotide triphosphate (dNTP) molecules like dATP(Adenine), dGTP(Guanine), dCTP(Cytosine) and dTTP(Thiamine) to the growing new DNA strand
• DNA polymerase has polymerization and exonuclease proofreading activity
- Polymerization from 5' to 3'
- Proofreading from 5' to 3' as
well as 3' to 5'
• The rate of polymerization by DNA polymerase is about 1000 nucleotide bases per second in prokaryotes
• DNA polymerase enzyme is efficient, and more accurate considering its proofreading activity.
DNA polymerase has three different subtypes in prokaryotes: Type I, II, and III. and five different subtypes in eukaryotes: α, β, γ, δ, ε.
• The DNA synthesis continues until the end when the strand ends, that is when polymerization stops, thus the entire chromosomal DNA is synthesized.
DNA vs RNA : Comparison and Differences
* RNA polymerase
• RNA polymerase is an enzyme that synthesises a single-stranded RNA molecule
• Molecular weight of RNA polymerase is 500 k Dalton.
• RNA polymerase functions during transcription, which is the synthesis of RNA
• RNA polymerase contains 6 subunits.
• RNA polymerase does not need a primer to initiate transcription
• RNA polymerase adds nucleotides directly. It inserts Nitrogenous bases like Adenine, Guanine, Cytosine and Uracil to the growing RNA strand.
• RNA polymerase only has a polymerization activity.
- Polymerization from 5' to 3'
• The rate of RNA polymerase for adding nucleotide bases is 40 to 80 nucleotide base per second.
• RNA polymerase is, inefficient, and inaccurate many times.
• RNA polymerase has five different subtypes in eukaryotes which are Type I, II, III, IV and V
• The polymerization is terminated when RNA polymerase finds the stop codon or termination codon(UAA, UGA and UAG) on the DNA strand.
