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Encyclopedia > Complementary DNA

In genetics, complementary DNA (cDNA) is DNA synthesized from a mature mRNA template. cDNA is often used to clone eukaryotic genes in prokaryotes. Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ... The general structure of a section of DNA Deoxyribonucleic acid (DNA) is a nucleic acid —usually in the form of a double helix— that contains the genetic instructions specifying the biological development of all cellular forms of life, and most viruses. ... The interaction of mRNA in a eukaryote cell. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista A eukaryote (IPA: ), also spelled eucaryote, is an organism with a complex cell or cells, in which the genetic material is organized into membrane-bound nucleus/nuclei. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... Domain Archaea - Archaebacteria Bacteria - Eubacteria Prokaryotes (from Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus, + suffix -otos, pl. ...

Contents


Overview

The central dogma of molecular biology outlines that in synthesizing proteins, DNA is transcribed into mRNA, which is translated into protein. One difference between eukaryotic and prokaryotic mRNA is that eukaryotic mRNA can contain introns (intervening sequences), which are not coding sequences, per se, and must be spliced out of the mRNA before it is translated into protein. Prokaryotic mRNA has no introns, so it is not subject to splicing. The central dogma of molecular biology was first enunciated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970: The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential information. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... The general structure of a section of DNA Deoxyribonucleic acid (DNA) is a nucleic acid —usually in the form of a double helix— that contains the genetic instructions specifying the biological development of all cellular forms of life, and most viruses. ... Transcription is the process through which a DNA sequence is enzymatically copied by an RNA polymerase to produce a complementary RNA. Or, in other words, the transfer of genetic information from DNA into RNA. In the case of protein-encoding DNA, transcription is the beginning of the process that ultimately... The interaction of mRNA in a eukaryote cell. ... Translation is the second process of protein biosynthesis (part of the overall process of gene expression). ... Diagram of the location of introns and exons within a gene. ... In genetics, splicing is a modification of genetic information prior to translation. ... In genetics, splicing is a modification of genetic information after transcription, in which introns are removed and exons are joined. ...


Often it is desirable to express eukaryotic genes in prokaryotic cells. A simplified method of doing so would include the addition of eukaryotic DNA to a prokaryotic host, which would transcribe the DNA to mRNA and then translate it to protein. However, as eukaryotic DNA has introns, and since prokaryotes lack the machinery to splice them, the splicing of eukaryotic DNA must be done prior to adding the eukaryotic DNA into the host (as well, before placing the eukaryotic DNA into the prokaryote, it must be methylated and a prokaryotic promoter region must be added). This spliced DNA is called complementary DNA.


Synthesis

Though there are several methods for doing so, cDNA is most often synthesized from mature (fully spliced) mRNA using the enzyme reverse transcriptase. This enzyme operates on a single strand of mRNA, generating its complementary DNA based on the pairing of RNA base pairs (A, U, G, C) to their DNA complements (T, A, C, G). To meet Wikipedias quality standards, this article or section may require cleanup. ... Headline text this website sucks your mothers dickIn molecular biology, two nucleotides on opposite complementary DNA or RNA strands that are connected via hydrogen bonds are called a base pair (often abbreviated bp). ...


To obtain eukaryotic cDNA whose introns have been spliced:

  1. A eukaryotic cell transcribes the DNA (from a gene) into RNA (pre-mRNA).
  2. The same cell processes the pre-mRNA strand by splicing out introns, and adding a poly-A tail and 5’ Methyl-Guanine cap.
  3. This mature mRNA strand is extracted from the cell.
  4. A poly-T oligonucleotide is hybridized onto the poly-A tail of the mature mRNA template. (Reverse transcriptase requires this double-stranded segment as a primer to start its operation.)
  5. Reverse transcriptase is added, along with deoxynucleotide triphosphates (A, T, G, C).

The reverse transcriptase scans the mature mRNA and synthesizes a sequence of DNA that complements the mRNA template. This strand of DNA is complementary DNA. Polyadenylation is the covalent linkage of a polyadenylyl moiety to a messenger RNA molecule. ... For the similarly-spelled vitamin compound, see Thiamine Thymine, also known as 5-methyluracil, is a pyrimidine nucleobase. ... Oligonucleotides are short sequences of nucleotides (RNA or DNA), typically with twenty or fewer base pairs. ... The chemical structure of adenosine Adenosine is a nucleoside comprised of adenine attached to a ribose (ribofuranose) moiety via a β-N9-glycosidic bond. ...


Note that the central dogma of molecular biology is broken in this process. The central dogma of molecular biology was first enunciated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970: The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential information. ...


Applications

Complementary DNA is often used in gene cloning or as gene probes or in the creation of a cDNA library. In genetics, a clone is a replica of all or part of a macromolecule (eg. ... Summary In order to identify a particular gene, a probe is used. ... In molecular biology, a cDNA library refers to a complete, or nearly complete, set of all the mRNAs contained within a cell or organism. ...


External links

  • H-Invitational Database
  • Functional Annotation of the Mouse database
Nucleic acids edit
Nucleobases: Adenine | Thymine | Uracil | Guanine | Cytosine | Purine | Pyrimidine
Nucleosides: Adenosine | Uridine | Guanosine | Cytidine | Deoxyadenosine | Thymidine | Deoxyguanosine | Deoxycytidine
Nucleotides: AMP | UMP | GMP | CMP | ADP | UDP | GDP | CDP | ATP | UTP | GTP | CTP | cAMP | cGMP
Deoxynucleotides: dAMP | dTMP | dGMP | dCMP | dADP | dTDP | dGDP | dCDP | dATP | dTTP | dGTP | dCTP
Nucleic acids: DNA | mtDNA | cDNA | GNA | RNA | mRNA | tRNA | rRNA | ncRNA | sgRNA | shRNA | siRNA | snRNA | miRNA | snoRNA | LNA | PNA | TNA | Oligonucleotide

 
 

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