Biological Sciences
Translation
Translation is the process by which a cell's machinery converts the genetic information encoded in mRNA into a sequence of amino acids, forming a protein. This process occurs in the ribosomes and involves the reading of the mRNA codons by transfer RNA molecules, which carry the corresponding amino acids. The resulting protein is essential for the structure and function of the cell.
Written by Perlego with AI-assistance
Related key terms
1 of 5
7 Key excerpts on "Translation"
- Yuri Kartavtsev(Author)
- 2015(Publication Date)
- CRC Press(Publisher)
3 Translation OF GENETIC INFORMATION. INTRODUCTION TO PROTEOMICS MAIN GOALS 3.1 Components that are Critical for Protein Synthesis 3.2 The Process of Translation: From RNA to Polypeptide 3.3 Heredity, Proteins and Function 3.4 Essential Proteomics 3.5 TRAINING COURSE, #3 SUMMARY 1. Translation describes synthesis of polypeptide chains in cells, under the direction of mRNA and in association with ribosomes. This process ultimately converts the information stored in the genetic code of the DNA forming a gene into the corresponding sequence of amino acids making up the polypeptide. 2. Translation is a complex energy-requiring process that also depends on charged tRNA molecules and numerous protein factors. Transfer RNA (tRNA) serves as an adaptor molecule between an mRNA triplet and the appropriate amino acid. 3. Investigation of nutritional requirements in Neurospora by Beadle with colleagues made it clear that mutations cause the loss of enzyme activity. Their work led to the concept of one-gene: one-enzyme . The one-gene: one-enzyme hypothesis was later revised. Pauling and Ingram’s investigations of hemoglobin from patients with sickle-cell anemia led to the discovery of the fact that one gene directs the synthesis of only one polypeptide chain. 4. The proposal suggesting that a gene nucleotide sequence speci fi es the sequence of amino acids in a polypeptide chain in a collinear manner was con fi rmed by experiments involving mutations in the tryptophan synthetase gene in E. coli. 5. Proteins, the end products of genes, demonstrate four levels of structural organization that collectively provide the chemical basis for their three-dimensional conformation, which is a basis for function of a molecule. 6. Of the myriad functions performed by proteins, the most in fl uential role is assumed by enzymes. These highly speci fi c, cellular catalysts play the central role in the production of all classes of molecules in living systems.
- Thomas M. Devlin(Author)
- 2015(Publication Date)
- Wiley-Liss(Publisher)
Three nucleotide sequences (codons) in mRNA specify a • single amino acid, the starting point of Translation, and the termination of the peptide chain. There are 64 possible codons and most amino acids are specified by more than one codon. The genetic code is termed degenerate and is almost universal. Translation is centered on RNA: mRNA transmits the genetic in- • formation, tRNA carries amino acids, and ribosomal RNA helps shape the ribosome and catalyzes peptide bond formation. Many proteins, enzymes, and factors are involved in protein synthesis. 210 • PART II TRANSMISSION OF INFORMATION 6.1 • INTRODUCTION Protein biosynthesis is called Translation because it involves the biochemical Translation of genetic information, stored and transmitted in the 4-letter alphabet and structural language of DNA, into the 20-letter alphabet and structural language of proteins. Translation is cen- tered on multiple functions of RNA: messenger RNA transmits the genetic information, transfer RNA carries amino acids and decodes the message, ribosomal RNA catalyzes pep- tide bond formation and makes up the core of the assembly bench, and very small RNAs are important regulators of the process. Cells vary in their need and ability to synthesize proteins. Terminally differentiated red blood cells lack the apparatus for Translation and have a life span of only 120 days. Other cells synthesize proteins they need to maintain concentrations of enzymes and other proteins. Growing and dividing cells must synthesize much larger amounts of protein, and some cells also produce proteins for export. For example, liver cells are protein factories that synthesize enzymes used in multiple metabolic pathways plus proteins for export including serum albumin, the major protein of blood plasma. 6.2 • COMPONENTS OF THE TranslationAL APPARATUS Messenger RNA Transmits Information Encoded in DNA Genetic information is inherited and stored as nucleotide sequences of DNA.
- Naoki Sugimoto(Author)
- 2021(Publication Date)
- Wiley-VCH(Publisher)
7 TranslationThe main points of the learning- Study basic molecular mechanisms of Translation reaction.
- Understand presence of various reaction steps for Translation modulation and maintenance.
- Study contributions of RNA structures to the Translation modulation.
7.1 Introduction
Protein is biopolymer consisting of amino acids polymerized in one dimension. In living system, the amino acid sequence of each protein is encoded in the sequence of messenger RNA (mRNA) that is originally encoded in DNA sequence. The sequence code on mRNA is decoded by a ribosome though a reaction termed Translation. Since the protein is the main functional molecule in extant living system, Translation is one of the most important biological reactions. Intracellular protein expression is modulated at not only transcription level but also at Translation level. The formation of unique RNA structures and their dynamic behaviors are the key factors to modulate and maintain the Translation system. This chapter describes contribution of RNA structures on Translation reaction as well as its basic knowledge. The contributions of structure dynamics of RNAs on gene expressions including replication, transcription, and Translation are described in Chapter 10 .7.2 RNAs Involved in Translation Machinery
There are three categories of RNAs such as mRNA, tRNA, and rRNA, which are directly involved in Translation machinery. mRNA is a template for the Translation. A region of nucleotide sequence in mature mRNA that is translated to a given protein is known as an open reading frame (ORF) (Figure 7.1 ). Correlation between nucleotide sequence and amino acid sequence was first proposed by Francis Crick as a sequence hypothesis. George Gamow, who is a theoretical physicist and cosmologist famous for his big bang theory, proposed that specific trinucleotide encodes one specific amino acid. The trinucleotide, which encodes a specific amino acid, is now known as a codon. Correlations between each codon and amino acid, which are conserved in all extant living system with few exceptions, have resolved by contributions from Marshall Nirenberg and Har Khorana (Figure 7.2 ). Outside of coding sequence, mRNA contains noncoding sequences. Untranslated regions (UTRs) at 5′ and 3′ ends of mRNA are called 5′ UTR and 3′ UTR, respectively. Prokaryotic mRNAs are polycistronic, which contains multiple ORFs in one mRNA. There are noncoding sequences between adjacent ORFs. In the case of eukaryotic mRNAs, primary transcript is a precursor messenger RNA (pre-mRNA) consisting of alternating exon and intron regions. Noncoding introns are excluded by posttranscriptional splicing that result in connected exons as a mature mRNA (Figure 7.1
eBook - PDFCell Biology A Comprehensive Treatise V4
Gene Expression: Translation and the Behavior of Proteins
- David M. Prescott(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
Thus, amino acids are polymerized into information-rich proteins with the consumption of energy. The machinery, i.e., ribo-somes, factors, tRNA's, and mRNA's, is unaltered and may be reutilized repeatedly to synthesize more proteins. In this chapter, the macromolecular components of the Translational machinery are identified and their structures, biogenesis, and cellular levels are described. The pathway for interaction of the components is then considered and attempts are made to describe the process in precise molecular or enzymological terms. Special attention is given to protein synthesis in eukaryotic cells, but prokaryotic components and mecha-nisms are described also. This is appropriate because the broad features of protein synthesis are remarkably similar in the two cell types, and 1. The Translational Machinery 3 because many bacterial structures and mechanisms are better understood at this time. The review develops the broad outlines and fundamental concepts of the Translational process. Fuller experimental details and exhaustive references are available in the numerous extensive reviews cited in the text. As the mechanism of protein synthesis is considered, three questions are of paramount importance: (1) How is the synthesis of proteins ini-tiated at the correct place in the mRNA? (2) How does protein synthesis proceed with a very low frequency of error? (3) How may the Translational process be modulated and its rate controlled? Ultimately we hope to explain all of the steps of protein synthesis in terms of well-understood chemical forces. The material which follows documents our progress to-wards this goal. II. MACROMOLECULAR COMPONENTS A. Aminoacyl-tRNA's Aminoacyl-tRNA's are directly involved as precursors in the polymeri-zation of amino acids on ribosomes. Transfer RNA's constitute a class of small single-stranded RNA molecules, each composed of 74 to 94 nu-cleotides with a mass of about 25,000 daltons.
- Aniruddha Datta, Edward R. Dougherty(Authors)
- 2018(Publication Date)
- CRC Press(Publisher)
6 Transcription and Translation In the last two chapters, we provided an introduction to DNA and proteins. The DNA contained in the genome of an organism primarily codes instructions for making proteins. Recall from the last chapter that there are only four DNA bases A, G, C, T and so an instruction written out in the language of DNA is basically an instruction written out in a language that has a 4-letter alphabet . Proteins, on the other hand, are made up of amino acids linked together by peptide bonds. Since there are 20 possible amino acids that occur in nature, the amino acid sequence for a protein can be thought of as a biological message written out using letters from a 20-letter alphabet . The natural question that comes up is how does the DNA message coded in the 4-letter alphabet map into the amino acid sequence of the appropriate protein. In this chapter, we will provide a detailed answer to this question. The DNA does not direct protein synthesis by itself but acts through certain intermediaries. When a particular protein is needed by the cell, the nucleotide sequence of the appropriate portion of the DNA molecule is first copied into another type of nucleic acid — RNA (ribonucleic acid). It is these RNA copies of short segments of the DNA that are used as templates to direct the synthesis of the protein. The process of copying the DNA into the appropriate RNA strands is referred to as transcription while the process of producing the protein from the information in the RNA is referred to as Translation . When a gene is being transcribed, it is said to be expressed or turned ON . The usual flow of genetic information is from DNA to RNA to protein. All cells, from the simplest bacteria to complex organisms such as humans, express their genetic information in this way. The principle is so fundamental to all of life that it is referred to as the central dogma of molecular biology .
eBook - PDF- S Bresler(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
Such RNA molecules apparently act as a template which directs the assembly of polypeptide chains. Messenger RNA is rapidly meta-bolized in bacterial cells throughout exponential growth ; its synthesis requires 20 to 30 seconds and it is generally degraded in the course of a few minutes. The steady-state concentration of mRNA in the cell is on the order of 3 to 8 % of the total cellular RNA. The number of mRNA molecules corresponding to a given protein is variable, depending on the requirements of the cell and on the rate at which each protein must be made. 2. Transfer RNA and the Activation of Amino Acids 451 Besides high-molecular-weight rRNA and mRNA, there is a low-molecular-weight RNA called transfer RNA (tRNA) present in the cell. This third type of RNA has a special function completely distinct from those of either previous class. It cova-lently binds amino acids and transports them to the sites of protein synthesis. Its role as an adaptor molecule in the actual assembly of the polypeptide chain was considered in the preceding chapter. Transfer RNA comprises between 10 and 20% of the total cellular RNA. Finally, monoribonucleotides and their phosphorylated derivatives such as ATP, GTP, and others play an important role in the cellular economy. They are widely distributed and often behave as coenzymes in addition to their participation in energy metabolism. We shall not be concerned with monoribonucleotides in this chapter since the reader can find a detailed exposition on this topic in any textbook of biochemistry. 2. Transfer RNA and the Activation of Amino Acids Since all types of RNA are implicated in protein synthesis, let us begin our discus-sion with transfer RNA (tRNA), actually a class of similar compounds that transport different amino acids to the sites of protein synthesis and there participate in the very first stages of polypeptide chain formation (1).
eBook - PDF- Gerald Karp, Janet Iwasa, Wallace Marshall(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
The differ- ences between the pioneer and steady-state rounds of Translation are discussed in Cell 142:368, 2010. 11.10 Translating Genetic Information 523 The Role of the Ribosome Now that we have assem- bled a complete ribosome, we can look more closely at the structure and function of this multisubunit structure. Ribo- somes are molecular machines, similar in some respects to the molecular motors described in Chapter 9. During Translation, a ribosome undergoes a repetitive cycle of mechanical changes that is driven with energy released by GTP hydrolysis. Unlike myosin or kinesin, which simply moves along a physical track, ribosomes move along an mRNA “tape” containing encoded information. Ribosomes, in other words, are programmable machines: The information stored in the mRNA determines the sequence of aminoacyl-tRNAs that the ribosome accepts during Translation. Another feature that distinguishes ribosomes from many other cellular machines is the importance of their com- ponent RNAs. Ribosomal RNAs play major roles in selecting tRNAs, ensuring accurate Translation, binding protein factors, and polymerizing amino acids (discussed in the Experimental Pathways feature). Early studies using high-resolution cryoelectron micro- scopic imaging techniques (Section 18.8) revealed the ribo- some to be a highly irregular structure with bulges, lobes, channels, and bridges (see Figure 2.59). These studies, carried out primarily by Joachim Frank and colleagues at Columbia University, also provided descriptions of major conforma- tional changes occurring within the ribosome during trans- lation. During the 1990s, major advances were made in the crystallization of ribosomes, and by the end of the decade the first reports of the X-ray crystallographic structure of prokaryotic ribosomes had appeared. Figure 11.48 shows the overall structure of the two ribosomal subunits of a bac- terial ribosome as revealed by X-ray crystallography.
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
