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Transfer RNA
Transfer RNADuring protein synthesis at the ribosome , the nucleic acid sequence of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) is translated into the amino acid sequence of a protein. Transfer RNA (tRNA) is an important adapter that "reads" the nucleic acid code in the messenger RNA (mRNA) and "writes" an amino acid sequence. Transfer RNAs transfer individual amino acids onto the growing polypeptide chain. There is at least one tRNA for each of the twenty naturally occurring amino acids. Each tRNA is transcribed from a different gene but the tRNA genes are clustered in the genome of some organisms. These clusters of genes are transcribed as a single unit, which results in the production of one large precursor RNA molecule. Individual tRNAs are then enzymatically separated from one another. Each tRNA is distinguished by a particular three-nucleotide sequence (the "anticodon") in one region, and by its ability to link up with a particular amino acid. The nucleotide sequence of the first tRNA was determined in 1965. As of 2000, there are more than one hundred tRNA sequences known, and they are all quite similar. All tRNA molecules are relatively short, composed of less than one hundred nucleotides. Unlike those found in DNA and mRNA, many of the nucleotides found in tRNA are modified to enhance their interactions. Although the three-dimensional shape of tRNA molecules has traditionally been depicted as a cloverleaf, X-ray crystallographic methods have revealed that the actual shape of a tRNA is an upside down letter L. During protein synthesis, the anticodon at one end of the L interacts with a triplet nucleotide in the mRNA called a codon . The correct tRNA will form "Watson-Crick"–type base pairs between the triplet anticodon on the tRNA and the triplet codon on the mRNA. The tRNAs must be exactly complementary at the first two codon positions (for example, A pairs with U, C pairs with G), but can vary in the third codon position. This flexibility in the third position is called "wobble," and it ultimately enables a single tRNA to bind to more than one triplet codon sequence. If the tRNA is not complementary as described above, it will be rejected from the ribosome, and its amino acid will not be incorporated into the polypeptide chain. At the other end of the L is the amino acid binding site. Enzymes (called aminoacyl tRNA synthetases) join the proper amino acid to its corresponding tRNA. This reaction requires ATP and the bond generated is a "high-energy" (that is, weak) bond. During the addition of the amino acid to the growing polypeptide, this bond is easily hydrolyzed , releasing the energy needed to power the process. see also Protein Synthesis; Ribosome; RNA James E. Blankenship BibliographyAlberts, Bruce, et al. Molecular Biology of the Cell, 4th ed. New York: Garland Publishing, 2000. Stryer, Lubert. Biochemistry, 4th ed. New York: W. H. Freeman and Company, 1995. |
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Blankenship, James E.. "Transfer RNA." Biology. 2002. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. Blankenship, James E.. "Transfer RNA." Biology. 2002. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1G2-3400700443.html Blankenship, James E.. "Transfer RNA." Biology. 2002. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3400700443.html |
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transfer-RNA
transfer-RNA (transfer ribonucleic acid, t-RNA) A generic term for a group of small RNA molecules, each composed of 70–80 nucleotides arranged in a clover-leaf pattern stabilized by hydrogen bonding. They are responsible for binding amino acids and transferring these to the ribosomes during the synthesis of a polypeptide (i.e. during translation). At the ribosomes, which are attached to the messenger-RNA (m-RNA), the ‘reading frame’ indicates the three m-RNA nucleotides that form the next triplet codon in the sequence: whichever t-RNA molecule carries the complementary anticodon can associate with the ribosome such that the amino acid that it bears can be joined on to the end of the growing polypeptide.
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MICHAEL ALLABY. "transfer-RNA." A Dictionary of Ecology. 2004. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "transfer-RNA." A Dictionary of Ecology. 2004. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O14-transferRNA.html MICHAEL ALLABY. "transfer-RNA." A Dictionary of Ecology. 2004. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O14-transferRNA.html |
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transfer-RNA
transfer-RNA (transfer ribonucleic acid, t-RNA) A generic term for a group of small RNA molecules, each composed of 70–80 nucleotides arranged in a cloverleaf pattern stabilized by hydrogen bonding. They are responsible for binding amino acids and transferring these to the ribosomes during the synthesis of a polypeptide (i.e. during translation). At the ribosomes, which are attached to the messenger-RNA (m-RNA), the ‘reading frame’ indicates the three m-RNA nucleotides that form the next triplet codon in the sequence: whichever t-RNA molecule carries the complementary anticodon can associate with the ribosome such that the amino acid that it bears can be joined on to the end of the growing polypeptide.
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MICHAEL ALLABY. "transfer-RNA." A Dictionary of Zoology. 1999. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "transfer-RNA." A Dictionary of Zoology. 1999. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O8-transferRNA.html MICHAEL ALLABY. "transfer-RNA." A Dictionary of Zoology. 1999. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O8-transferRNA.html |
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transfer-RNA
transfer-RNA (transfer ribonucleic acid, t-RNA) A generic term for a group of small RNA molecules, each composed of 70–80 nucleotides arranged in a clover-leaf pattern stabilized by hydrogen bonding. They are responsible for binding amino acids and transferring these to the ribosomes during the synthesis of a polypeptide (i.e. during translation). At the ribosomes, which are attached to the messenger-RNA (m-RNA), the ‘reading frame’ indicates the 3 m-RNA nucleotides that form the next triplet codon in the sequence: whichever t-RNA molecule carries the complementary anticodon can associate with the ribosome such that the amino acid that it bears can be joined on to the end of the growing polypeptide.
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MICHAEL ALLABY. "transfer-RNA." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. MICHAEL ALLABY. "transfer-RNA." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O7-transferRNA.html MICHAEL ALLABY. "transfer-RNA." A Dictionary of Plant Sciences. 1998. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O7-transferRNA.html |
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transfer RNA
transfer RNA (trans-fer) n. a type of RNA whose function is to attach the correct amino acid to the protein chain being synthesized at a ribosome. See also translation.
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"transfer RNA." A Dictionary of Nursing. 2008. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "transfer RNA." A Dictionary of Nursing. 2008. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O62-transferRNA.html "transfer RNA." A Dictionary of Nursing. 2008. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O62-transferRNA.html |
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transfer RNA
trans·fer RNA • n. Biochem. RNA consisting of folded molecules that transport amino acids from the cytoplasm of a cell to a ribosome. |
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"transfer RNA." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "transfer RNA." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O999-transferrna.html "transfer RNA." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-transferrna.html |
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transfer RNA
transfer RNA See RNA.
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Cite this article
"transfer RNA." A Dictionary of Biology. 2004. Encyclopedia.com. 28 May. 2012 <http://www.encyclopedia.com>. "transfer RNA." A Dictionary of Biology. 2004. Encyclopedia.com. (May 28, 2012). http://www.encyclopedia.com/doc/1O6-transferRNA.html "transfer RNA." A Dictionary of Biology. 2004. Retrieved May 28, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-transferRNA.html |
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