FACTOID # 13: New York has America's lowest percentage of residents who are veterans.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Transfer RNA
Transfer RNA
Transfer RNA

Transfer RNA (abbreviated tRNA), first hypothesized by Francis Crick, is a small RNA chain (73-93 nucleotides) that transfers a specific amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. It has a 3' terminal site for amino acid attachment. This covalent linkage is catalyzed by an aminoacyl tRNA synthetase. It also contains a three base region called the anticodon that can base pair to the corresponding three base codon region on mRNA. Each type of tRNA molecule can be attached to only one type of amino acid, but because the genetic code contains multiple codons that specify the same amino acid, tRNA molecules bearing different anticodons may also carry the same amino acid. Image File history File links Size of this preview: 408 × 599 pixel Image in higher resolution (448 × 658 pixel, file size: 23 KB, MIME type: image/png) diagram of tRNA created by Pixeltoo 15:52, 4 Feb 2005 (UTC) File links The following pages on the English Wikipedia link to... Image File history File links Size of this preview: 408 × 599 pixel Image in higher resolution (448 × 658 pixel, file size: 23 KB, MIME type: image/png) diagram of tRNA created by Pixeltoo 15:52, 4 Feb 2005 (UTC) File links The following pages on the English Wikipedia link to... Francis Harry Compton Crick OM FRS (8 June 1916 – 28 July 2004) was an English molecular biologist, physicist, and neuroscientist, who is most noted for being one of the co-discoverers of the structure of the DNA molecule in 1953. ... Left: An RNA strand, with its nitrogenous bases. ... This article is about the class of chemicals. ... Translation is the second stage of protein biosynthesis (part of the overall process of gene expression). ... This article is about the class of chemicals. ... A nucleotide is a chemical compound that consists of 3 portions: a heterocyclic base, a sugar, and one or more phosphate groups. ... An anticodon is a unit made up of nucleotides that plays an important role in various DNA cycles, including DNA transcription. ... RNA codons. ... The interaction of mRNA in a eukaryote cell. ... For a non-technical introduction to the topic, see Introduction to Genetics. ...

Contents

Structure

Structure of tRNA. CCA tail in orange, Acceptor stem in purple, D arm in red, Anticodon arm in blue with Anticodon in black, T arm in green.
Structure of tRNA. CCA tail in orange, Acceptor stem in purple, D arm in red, Anticodon arm in blue with Anticodon in black, T arm in green.

tRNA has primary structure, secondary structure (usually visualized as the cloverleaf structure), and tertiary structure (all tRNAs have a similar L-shaped 3D structure that allows them to fit into the P and A sites of the ribosome). Image File history File links Download high resolution version (1061x1056, 525 KB) Summary Three dimensional image of a tRNA. Coloring: CCA tail in orange Acceptor stem in purple D arm in red Anticodon arm in blue with Anticodon in black. ... Image File history File links Download high resolution version (1061x1056, 525 KB) Summary Three dimensional image of a tRNA. Coloring: CCA tail in orange Acceptor stem in purple D arm in red Anticodon arm in blue with Anticodon in black. ... A protein primary structure is a chain of amino acids. ... A representation of the 3D structure of the myoglobin protein. ... In biochemistry and chemistry, the tertiary structure of a protein or any other macromolecule is its three-dimensional structure, as defined by the atomic coordinates. ... Translation is the second stage of protein biosynthesis (part of the overall process of gene expression). ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ...

  1. The 5'-terminal phosphate group.
  2. The acceptor stem is a 7-bp stem made by the base pairing of the 5'-terminal nucleotide with the 3'-terminal nucleotide (which contains the CCA 3'-terminal group used to attach the amino acid). The acceptor stem may contain non-Watson-Crick base pairs.
  3. The CCA tail is a CCA sequence at the 3' end of the tRNA molecule. This sequence is important for the recognition of tRNA by enzymes critical in translation. In prokaryotes, the CCA sequence is transcribed. In eukaryotes, the CCA sequence is added during processing and therefore does not appear in the tRNA gene.
  4. The D arm is a 4 bp stem ending in a loop that often contains dihydrouridine.
  5. The anticodon arm is a 5-bp stem whose loop contains the anticodon.
  6. The T arm is a 5 bp stem containing the sequence TΨC where Ψ is a pseudouridine.
  7. Bases that have been modified, especially by methylation, occur in several positions outside the anticodon. The first anticodon base is sometimes modified to inosine (derived from adenine) or pseudouridine (derived from uracil).

In molecular biology, the 5 end and the 3 end (pronounced 5-prime and 3-prime) are respectively the leading and tail ends of a strand of nucleic acid. ... A phosphate, in inorganic chemistry, is a salt of phosphoric acid. ... In molecular biology, the 5 end and the 3 end (pronounced 5-prime and 3-prime) are respectively the leading and tail ends of a strand of nucleic acid. ... Transfer RNA The D arm is a feature in the tertiary structure of transfer RNA. It is comprised of the two D stems (four base pairs each each; 10-13 and 22-25) and the D loop. ... Dihydrouridine is a pyrimidine which is the result of adding two hydrogen atoms to a uridine. ... Transfer RNA Transfer RNA (abbreviated tRNA), first hypothesized by Francis Crick, is a small RNA chain (73-93 nucleotides) that transfers a specific amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. ... The T-arm or T-loop is a specialized region on the tRNA molecule which acts as a special recognition site for the ribosome to allow a tRNA-ribosome complex to form during the process of protein biosynthesis. ... Pseudouridine (abbreviated Ψ) is the C-glycoside isomer of the nucleoside uridine, and it is the most prevalent of the over one hundred different modified nucleosides found in RNA [1]. Ψ is found in all species and in all classes of RNA except mRNA [1]. Ψ is formed by enzymes called Ψ synthases, which... Methylation is a term used in the chemical sciences to denote the attachment or substitution of a methyl group on various substrates. ... Inosine is a molecule (known as a nucleoside) that is formed when hypoxanthine is attached to a ribose ring (also known as a ribofuranose) via a β-N9-glycosidic bond. ... Pseudouridine (abbreviated Ψ) is the C-glycoside isomer of the nucleoside uridine, and it is the most prevalent of the over one hundred different modified nucleosides found in RNA [1]. Ψ is found in all species and in all classes of RNA except mRNA [1]. Ψ is formed by enzymes called Ψ synthases, which...

Anticodon

An anticodon [1] is a unit made up of three nucleotides that correspond to the three bases of the codon on the mRNA. Each tRNA contains a specific anticodon triplet sequence that can base-pair to one or more codons for an amino acid. For example, one codon for lysine is AAA; the anticodon of a lysine tRNA might be UUU. Some anticodons can pair with more than one codon due to a phenomenon known as wobble base pairing. Frequently, the first nucleotide of the anticodon is one of two not found on mRNA: inosine and pseudouridine, which can hydrogen bond to more than one base in the corresponding codon position. In the genetic code, it is common for a single amino acid to occupy all four third-position possibilities; for example, the amino acid glycine is coded for by the codon sequences GGU, GGC, GGA, and GGG. A nucleotide is an organic molecule consisting of a heterocyclic nucleobase (a purine or a pyrimidine), a pentose sugar (deoxyribose in DNA or ribose in RNA), and a phosphate or polyphosphate group. ... Lysine is one of the 20 amino acids normally found in proteins. ... Wobble base pairs for inosine Wobble base pairs for Uracil A wobble base pair is a G-U and I-U / I-A / I-C pair fundamental in RNA secondary structure. ... Inosine is a molecule (known as a nucleoside) that is formed when hypoxanthine is attached to a ribose ring (also known as a ribofuranose) via a β-N9-glycosidic bond. ... Pseudouridine (abbreviated Ψ) is the C-glycoside isomer of the nucleoside uridine, and it is the most prevalent of the over one hundred different modified nucleosides found in RNA [1]. Ψ is found in all species and in all classes of RNA except mRNA [1]. Ψ is formed by enzymes called Ψ synthases, which... An example of a quadruple hydrogen bond between a self-assembled dimer complex reported by Meijer and coworkers. ... For a non-technical introduction to the topic, see Introduction to Genetics. ... For the plant, see Glycine (plant). ...


To provide a one-to-one correspondence between tRNA molecules and codons that specify amino acids, 61 tRNA molecules would be required per cell. However, many cells contain fewer than 61 types of tRNAs because the wobble base is capable of binding to several, though not necessarily all, of the codons that specify a particular amino acid[2].


Aminoacylation

Aminoacylation is the process of adding an aminoacyl group to a compound. It produces tRNA molecules with their CCA 3' ends covalently linked to an amino acid. Aminoacylation is the process of adding an aminoacyl group to a compound. ... This article is about the class of chemicals. ...


Each tRNA is aminoacylated (or charged) with a specific amino acid by an aminoacyl tRNA synthetase. There is normally a single aminoacyl tRNA synthetase for each amino acid, despite the fact that there can be more than one tRNA, and more than one anticodon, for an amino acid. Recognition of the appropriate tRNA by the synthetases is not mediated solely by the anticodon, and the acceptor stem often plays a prominent role. Aminoacylation is the process of adding an aminoacyl group to a compound. ... An aminoacyl tRNA synthetase (abbreviated aaRs) is an enzyme that catalyzes the binding of a specific amino acid to a tRNA to form an aminoacyl-tRNA. The synthetase hydrolyzes ATP to bind the appropriate amino acid to the 3 hydroxyl of the tRNA molecule. ...


Reaction:

  1. amino acid + ATP → aminoacyl-AMP + PPi
  2. aminoacyl-AMP + tRNA → aminoacyl-tRNA + AMP

tRNA genes

Organisms vary in the number of tRNA genes in their genome. The nematode worm C. elegans, a commonly used model organism in genetics studies, has 19,000 genes in its nuclear genome, of which 659 code for tRNA[3]. The budding yeast Saccharomyces cerevisiae has 275 tRNA genes in its genome. In the human genome, which according to current estimates has about 25,000 genes in total, there are about 2000 non-coding RNA genes, which include tRNA genes. There are 22 mitochondrial tRNA genes[4]; 497 nuclear genes encoding cytoplasmic tRNA molecules and there are 324 tRNA-derived putative pseudogenes.[5] This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... Classes Adenophorea    Subclass Enoplia    Subclass Chromadoria Secernentea    Subclass Rhabditia    Subclass Spiruria    Subclass Diplogasteria    Subclass Tylenchia The nematodes or roundworms (Phylum Nematoda from Greek (nema): thread + -ode like) are one of the most common phyla of animals, with over 20,000 different described species (over 15,000 are parasitic). ... Binomial name Maupas, 1900 Caenorhabditis elegans (IPA: ) is a free-living nematode (roundworm), about 1 mm in length, which lives in temperate soil environments. ... This article is about the general scientific term. ... HeLa cells stained for DNA with the Blue Hoechst dye. ... Binomial name Meyen ex E.C. Hansen Saccharomyces cerevisiae is a species of budding yeast. ... A non-coding RNA (ncRNA) is any RNA molecule that is not translated into a protein. ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... A pseudogene is a nucleotide sequence that is part of the genome of an organism that appears to code for a gene product (typically a protein) but does not (or no longer does so). ...


Cytoplasmic tRNA genes can be grouped into 49 families according to their anticodon features. These genes are found on all chromosomes, except 22 and Y chromosome. High clustering on 6p is observed (140 tRNA genes), as well on 1 chromosome.[5] This article is about the biological chromosome. ...


tRNA molecules are transcribed (in eukaryotic cells) by RNA polymerase III, unlike messenger RNA which is transcribed by RNA polymerase II. Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... RNA polymerase III (also called Pol III) transcribes DNA to synthesize ribosomal 5S rRNA, tRNA and other small RNAs. ... The life cycle of an mRNA in a eukaryotic cell. ... RNA polymerase II (also called RNAP II and Pol II) transcribes DNA to synthesize precursors of mRNA and most snRNA. A 550 kDa complex of 12 subunits, RNAP II is the most studied type of RNA polymerase. ...


History

Significant research on structure was conducted in the early 1960s by Alex Rich and Don Caspar, two researchers in Boston, the Jacques Fresco group in Princeton University and a United Kingdom group at King's College London.[6] A later publication reported the primary structure in 1965 by Robert W. Holley. The secondary and tertiary structures were derived from X-ray crystallography studies reported independently in 1974 by American and British research groups headed, respectively, by Alexander Rich and Aaron Klug. Alexander Rich, MD (American; born 1925) is a biologist and biophysicist. ... Princeton University is a private coeducational research university located in Princeton, New Jersey. ... For other uses, see Kings College. ... Robert W. Holley, the structure of a tRNA is shown in the background Dr Robert W. Holley (January 28, 1922 - February 11, 1993) was an American biochemist, he was awarded the Nobel Prize in Physiology or Medicine in 1968 for describing the structure of alanine transfer RNA, linking DNA and... X-ray crystallography, also known as single-crystal X-ray diffraction, is the oldest and most common crystallographic method for determining the structure of molecules. ...


References

  1. ^ Felsenfeld G, Cantoni G. "Use of thermal denaturation studies to investigate the base sequence of yeast serine sRNA". Proc Natl Acad Sci U S A 51: 818-26. PMID 14172997. 
  2. ^ Lodish H, Berk A, Matsudaira P, Kaiser CA, Krieger M, Scott MP, Zipursky SL, Darnell J. (2004). Molecular Biology of the Cell. WH Freeman: New York, NY. 5th ed.
  3. ^ Hartwell LH, Hood L, Goldberg ML, Reynolds AE, Silver LM, Veres RC. (2004). Genetics: From Genes to Genomes 2nd ed. McGraw-Hill: New York, NY. p 264.
  4. ^ Ibid. p 529.
  5. ^ a b Lander E. et al. (2001). "Initial sequencing and analysis of the human genome". Nature 409 (6822): 860-921. PMID 11237011. 
  6. ^ Brian F.C. Clark (October 2006). "The crystal structure of tRNA". J. Biosci. 31 (4): 453-7. PMID 17206065. 

See also

The interaction of mRNA in a eukaryote cell. ... A non-coding RNA (ncRNA) is any RNA molecule that functions without being translated into a protein. ... A non-coding RNA (ncRNA) is any RNA molecule that is not translated into a protein. ... Diagram of the location of introns and exons within a gene. ... Translation is the second process of protein biosynthesis (part of the overall process of gene expression). ...

External links


v  d  e
Major families of biochemicals
Peptides | Amino acids | Nucleic acids | Carbohydrates | Nucleotide sugars | Lipids | Terpenes | Carotenoids | Tetrapyrroles | Enzyme cofactors | Steroids | Flavonoids | Alkaloids | Polyketides | Glycosides
Analogues of nucleic acids: Types of Nucleic Acids Analogues of nucleic acids:
Nucleobases: Purine (Adenine, Guanine) | Pyrimidine (Uracil, Thymine, Cytosine)
Nucleosides: Adenosine/Deoxyadenosine | Guanosine/Deoxyguanosine | Uridine | Thymidine | Cytidine/Deoxycytidine
Nucleotides: monophosphates (AMP, UMP, GMP, CMP) | diphosphates (ADP, UDP, GDP, CDP) | triphosphates (ATP, UTP, GTP, CTP) | cyclic (cAMP, cGMP, cADPR)
Deoxynucleotides: monophosphates (dAMP, TMP, dGMP, dCMP) | diphosphates (dADP, TDP, dGDP, dCDP) | triphosphates (dATP, TTP, dGTP, dCTP)
Ribonucleic acids: RNA | mRNA | piRNA | tRNA | rRNA | ncRNA | gRNA | shRNA | siRNA | snRNA | miRNA | snoRNA
Deoxyribonucleic acids: DNA | mtDNA | cDNA | plasmid | Cosmid | BAC | YAC | HAC
Analogues of nucleic acids: GNA | PNA | TNA | Morpholino | LNA

  Results from FactBites:
 
RNA - Wikipedia, the free encyclopedia (1158 words)
RNA serves as the template for translation of genes into proteins, transferring amino acids to the ribosome to form proteins, and also translating the transcript into proteins.
Transfer RNA is a small RNA chain of about 74-93 nucleotides that transfers a specific amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation.
RNA genes (sometimes referred to as non-coding RNA or small RNA) are genes that encode RNA that is not translated into a protein.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m