Examples of polymerase in the following topics:
-
- RNA Polymerase II (RNAPII) transcribes the major share of eukaryotic genes, so this section will mainly focus on how this specific polymerase accomplishes elongation and termination.
- RNA Polymerase II is a complex of 12 protein subunits.
- The RNA Polymerase travels along the template DNA one nucleotide at at time.
- RNA Polymerase II has no specific signals that terminate its transcription.
- FACT removes two of the histones from the nucleosome immediately ahead of RNA Polymerase, loosening the packaging so that RNA Polymerase II can continue transcription.
-
- Transcription elongation begins with the release of the polymerase σ subunit and terminates via the rho protein or via a stable hairpin.
- The transcription elongation phase begins with the release of the σ subunit from the polymerase.
- Near the end of the gene, the polymerase encounters a run of G nucleotides on the DNA template and it stalls.
- As a result, the rho protein collides with the polymerase.
- As the polymerase nears the end of the gene being transcribed, it encounters a region rich in C–G nucleotides.
-
- Instead of a single polymerase comprising five subunits, the eukaryotes have three polymerases that are each made up of 10 subunits or more.
- RNA polymerase I synthesizes all of the rRNAs except for the 5S rRNA molecule.
- RNA polymerase III is also located in the nucleus.
- Not all miRNAs are transcribed by RNA Polymerase II, RNA Polymerase III transcribes some of them.
- A generalized promoter of a gene transcribed by RNA polymerase II is shown.
-
- Prokaryotes use the same RNA polymerase to transcribe all of their genes.
- In E. coli, the polymerase is composed of five polypeptide subunits, two of which are identical.
- Four of these subunits, denoted α, α, β, and β', comprise the polymerase core enzyme.
- The polymerase comprised of all five subunits is called the holoenzyme.
- The σ subunit dissociates from the polymerase after transcription has been initiated.
-
- Taq polymerase is an enzyme that was first isolated from the microbe Thermus aquaticus.
- The isolation of this polymerase has resulted in the ability to perform polymerase chain reactions (PCR), a process used to amplify DNA segments, in a single step.
- Prior to the isolation of Taq polymerase, a new DNA polymerase had to be added to the reaction after every cycle because of thermal denaturation.
- Currently, Taq polymerase is manufactured and produced on a large scale and is available for commercial sale.
- Describe how Taq polymerase, restriction enzymes and DNA ligase are used in molecular biology
-
- RNA polymerase binds to the transcription initiation complex, allowing transcription to occur.
- Once this transcription initiation complex is assembled, RNA polymerase can bind to its upstream sequence.
- When bound along with the transcription factors, RNA polymerase is phosphorylated.
- A generalized promoter of a gene transcribed by RNA polymerase II is shown.
- RNA polymerase II then binds and forms the transcription initiation complex.
-
- The polymerase chain reaction (PCR) is a method by which DNA is amplified.
- Primers (short DNA fragments) containing sequences complementary to the target region, along with a DNA polymerase (after which the method is named) are key components to enable selective and repeated amplification.
- Taq polymerase or another DNA polymerase with a temperature optimum at around 70 °C
- Deoxynucleoside triphosphates (dNTPs; nucleotides containing triphosphate groups), the building-blocks from which the DNA polymerase synthesizes a new DNA strand
- Extension/elongation step: The temperature at this step depends on the DNA polymerase used; Taq polymerase has its optimum activity temperature at 75-80 °C, and commonly a temperature of 72 °C is used with this enzyme.
-
- Prokaryotic DNA is replicated by DNA polymerase III in the 5' to 3' direction at a rate of 1000 nucleotides per second.
- In prokaryotes, three main types of polymerases are known: DNA pol I, DNA pol II, and DNA pol III.
- DNA polymerase can only extend in the 5' to 3' direction, which poses a slight problem at the replication fork.
- DNA polymerase III uses this primer to synthesize the daughter DNA strand.
- DNA polymerase I replaces the RNA primer with DNA.
-
- This process will continue until the DNA polymerase reaches the end of the template strand.
- All newly synthesized polynucleotide strands must be initiated by a specialized RNA polymerase called primase.
- DNA polymerase can only synthesize new strands in the 5' to 3' direction.
- DNA polymerase halts when it reaches a section of DNA template that has already been replicated.
- An RNA primer is synthesized by primase and is elongated by the DNA polymerase.
-
- Specifically, in bacteria, sigma factors are necessary for recognition of RNA polymerase to the gene promoter site.
- The sigma factor allows the RNA polymerase to properly bind to the promoter site and initiate transcription which will result in the production of an mRNA molecule.
- Once the role of the sigma factor is completed, the protein leaves the complex and RNA polymerase will continue with transcription.
- The anti-sigma factors will bind to the RNA polymerase and prevent its binding to sigma factors present at the promoter site.