Page 90 - Academic Press Encyclopedia of Physical Science and Technology 3rd Molecular Biology

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Encyclopedia of Physical Science and Technology EN017F-788 August 3, 2001 16:27

Translation of RNA to Protein

R. A. Cox
H. R. V. Arnstein
National Institute for Medical Research

I. Introduction
II. mRNA Structure and the Genetic Code
III. Transfer RNA
IV. Ribosome Structure and Function in Translation
V. Translational Control of Gene Expression
VI. Concluding Remarks

GLOSSARY cleotide or polypeptide. In DNA, the two strands have
opposite polarity; that is, they run in opposite direc-

Anticodon Three consecutive bases in tRNA that bind to tions (5 → 3 and 3 → 5 ). The polarity of a polypep-

a specific mRNA codon by complementary antiparallel tide is defined as running from the N-terminus to the
base-pairing. C-terminus.
Antiparallel base-pairing Pairing through specific hy- Reading frame One of three possible ways of trans-
drogen bonds between base residues of two polynu- lating groups of three nucleotides in mRNA. The ap-
cleotide chains or two segments of a single chain with propriate reading frame is determined by the initiation

phosphodiesterbonds running in the 5 → 3 direction codon.

in one chain or segment and in the 3 → 5 direction Template strand The strand of the DNA double helix
in the other. In DNA and RNA the hydrogen bonds that is used as a template for transcription of RNA.
are usually formed between complementary base pairs It has a base sequence complementary to the RNA
(A with either T or U, and G with C). transcript.
Elongation The stepwise addition of amino acids to the Termination The end of polypeptide synthesis, which is
carboxyl terminus of a growing polypeptide chain. signaled by a codon for which there is no corresponding
Initiation A multistep reaction between ribosomal sub- aminoacyl-tRNA. When the ribosome reaches a termi-
units, charged initiator transfer RNA, and messenger nation codon in the mRNA, the polypeptide is released
RNA that results in apposition of the ribosome-bound and the ribosome-mRNA-tRNA complex dissociates.
initiator Met-tRNA with an AUG initiator codon in Translation The stepwise synthesis of a polypeptide
mRNA. In this position, the ribosome is poised to form with an amino acid sequence determined by the nu-
the first peptide bond. cleotide sequence of the mRNA coding region. The
Polarity The asymmetry of a polymer such as a polynu- genetic code relates each amino acid to a group of three

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