polymerase chain reaction

(noun)

a technique in molecular biology for creating multiple copies of DNA from a sample

Related Terms

  • denaturation
  • electrophoresis

Examples of polymerase chain reaction in the following topics:

  • Basic Techniques to Manipulate Genetic Material (DNA and RNA)

    • The DNA can be replicated by the DNA polymerase enzyme.
    • Polymerase chain reaction (PCR) is a technique used to amplify specific regions of DNA for further analysis .
    • Polymerase chain reaction, or PCR, is used to amplify a specific sequence of DNA.
    • Primers—short pieces of DNA complementary to each end of the target sequence—are combined with genomic DNA, Taq polymerase, and deoxynucleotides.
    • Taq polymerase is a DNA polymerase isolated from the thermostable bacterium Thermus aquaticus that is able to withstand the high temperatures used in PCR.
  • Types and Functions of Proteins

    • Salivary amylase is an enzyme in the mouth that breaks down starch (a long carbohydrate chain) into amylose (a short chain of glucose molecules).
    • These long chains of amino acids are critically important for:
    • Enzymes are proteins that catalyze biochemical reactions, which otherwise would not take place.
    • The substrates are the reactants that undergo the chemical reaction catalyzed by the enzyme.
    • A catabolic enzyme reaction showing the substrate matching the exact shape of the active site.
  • DNA Sequencing Techniques

    • The Sanger method is also known as the dideoxy chain termination method.
    • This sequencing method is based on the use of chain terminators, the dideoxynucleotides (ddNTPs).
    • As such the following components are needed: template DNA (which will the be DNA whose sequence will be determined), DNA Polymerase to catalyze the replication reactions, a primer that basepairs prior to the portion of the DNA you want to sequence, dNTPs, and ddNTPs.
    • Most of the time in a Sanger sequencing reaction, DNA Polymerase will add a proper dNTP to the growing strand it is synthesizing in vitro.
    • Each sequencing reaction is a modified replication reaction involving flourescently-tagged nucleotides, but no chain-terminating dideoxy nucleotides are needed.
  • Elongation and Termination in Prokaryotes

    • The transcription elongation phase begins with the release of the σ subunit from the polymerase.
    • Rho-dependent termination is controlled by the rho protein, which tracks along behind the polymerase on the growing mRNA chain.
    • 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.
  • Initiation of Transcription in Eukaryotes

    • 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 III is also located in the nucleus.
    • The tRNAs have a critical role in translation: they serve as the adaptor molecules between the mRNA template and the growing polypeptide chain.
    • 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.
  • DNA Replication in Prokaryotes

    • One of the key players is the enzyme DNA polymerase, which adds nucleotides one by one to the growing DNA chain that are complementary to the template strand.
    • When the bond between the phosphates is broken, the energy released is used to form the phosphodiester bond between the incoming nucleotide and the growing chain.
    • In prokaryotes, three main types of polymerases are known: DNA pol I, DNA pol II, and DNA pol III.
    • DNA polymerase III uses this primer to synthesize the daughter DNA strand.
    • DNA polymerase I replaces the RNA primer with DNA.
  • The Protein Synthesis Machinery

    • The peptidyl-tRNA carrying the growing polypeptide chain is held in the P site.
    • The tRNA molecules are transcribed by RNA polymerase III.
    • In eukaryotes, tRNA mole are transcribed from tRNA genes by RNA polymerase III.
    • The process of pre-tRNA synthesis by RNA polymerase III only creates the RNA portion of the adaptor molecule.
    • These enzymes first bind and hydrolyze ATP to catalyze the formation of a covalent bond between an amino acid and adenosine monophosphate (AMP); a pyrophosphate molecule is expelled in this reaction.
  • DNA Replication in Eukaryotes

    • The template strand specifies which of the four DNA nucleotides (A, T, C, or G) is added at each position along the new chain.
    • This process will continue until the DNA polymerase reaches the end of the template strand.
    • 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.
  • DNA Repair

    • Most mistakes during replication are corrected by DNA polymerase during replication or by post-replication repair mechanisms.
    • DNA replication is a highly accurate process, but mistakes can occasionally occur as when a DNA polymerase inserts a wrong base.
    • The polymerase checks whether the newly-added base has paired correctly with the base in the template strand.
    • Thus, DNA polymerase is able to remove the incorrectly-incorporated bases from the newly-synthesized, non-methylated strand.
    • Spontaneous mutations occur without any exposure to any environmental agent; they are a result of natural reactions taking place within the body.
  • The Two Parts of Photosynthesis

    • Light-dependent and light-independent reactions are two successive reactions that occur during photosynthesis.
    • Just as the name implies, light-dependent reactions require sunlight.
    • Photosystems consist of a light-harvesting complex and a reaction center.
    • In photosystem I, the electron comes from the chloroplast electron transport chain.
    • Photosynthesis takes place in two stages: light-dependent reactions and the Calvin cycle (light-independent reactions).
Subjects
  • Accounting
  • Algebra
  • Art History
  • Biology
  • Business
  • Calculus
  • Chemistry
  • Communications
  • Economics
  • Finance
  • Management
  • Marketing
  • Microbiology
  • Physics
  • Physiology
  • Political Science
  • Psychology
  • Sociology
  • Statistics
  • U.S. History
  • World History
  • Writing

Except where noted, content and user contributions on this site are licensed under CC BY-SA 4.0 with attribution required.