Single-stranded ribonucleic acid

Hepatitis A is a non-enveloped single-stranded ribonucleic acid (RNA) virus classified as the Hepatovirus genus under I the Picornaviridae family.1 The only host for the HAV is... 

A process called transcription generates messenger RNAs (mRNA). A large enzyme, RNA polymerase II, functions as a catalyst to synthesize long chains of single-stranded ribonucleic acids in the presence of Mg2+ ions and the four rNTPs. It codes for proteins and occurs in almost all sizes. 

RNA Ribonucleic acid (RNA) is a single-stranded nucleic acid. (There are exceptions, of course. See Chapter 18.) It contains the pentose ribose, in contrast... 

Cellular protein biosynthesis involves the following steps. One strand of double-stranded DNA serves as a template strand for the synthesis of a complementary single-stranded messenger ribonucleic acid (mRNA) in a process called transcription. This mRNA in turn serves as a template to direct the synthesis of the protein in a process called translation. The codons of the mRNA are read sequentially by transfer RNA (tRNA) molecules, which bind specifically to the mRNA via triplets of nucleotides that are complementary to the particular codon, called an anticodon. Protein synthesis occurs on a ribosome, a complex consisting of more than 50 different proteins and several stmctural RNA molecules, which moves along the mRNA and mediates the binding of the tRNA molecules and the formation of the nascent peptide chain. The tRNA molecule carries an activated form of the specific amino acid to the ribosome where it is added to the end of the growing peptide chain. There is at least one tRNA for each amino acid. 

Let us consider the structure of the tobacco mosaic virus first. As shown schematically in Figure 5.1, it is composed of a single strand of ribonucleic acid, RNA, covered by a sheath formed from 2130 identical protein units. Thus the whole virus constitutes a rather simple supramolecular assembly. By changing... 

Transcription starts with the process hy which the genetic information is transcribed onto a form of RNA, called mRNA. Ribonucleic acid, RNA, is structurally similar to DNA with the exceptions that its nucleotides contain ribose, instead of a 2 -deoxyribose, and the base thymine is replaced by uracil. There are three major types of RNA depending on their specific functions. However, all three types of RNA are much smaller than DNA and they are single stranded, rather than double stranded. 

In DNA and the related single-stranded RNA (ribonucleic acid), the phosphate units are monomeric and play a strictly structural role. Phosphates, however, are also essential to the metabolism of living cells, in which formation and subsequent hydrolysis of phosphate-phosphate bonds... 

Ribonucleic acid, or RNA, also gets its name from the sugar group it contains, in this case, ribose. In many ways, RNA is like DNA. It has a sugar-phosphate backbone with nitrogen bases attached to it, and it also contains the bases adenine (A), cytosine (C), and guanine (G). However, RNA does not contain thymine (T). Instead, the fourth base in RNA is uracil (U). Unlike DNA, RNA is a single-stranded molecule. 

RNA (ribonucleic acid) A single-stranded genetic material critical for protein synthesis in living cells. 

As much of the terminology used in molecular biology may be unfamiliar to some readers, it is appropriate to define some of the vocabulary and this is given in an appendix to this chapter. There are two types of nucleic acids, the ribonucleic acids (RNA) and the deoxyribonucleic acids (DNA). Genetic information is carried in the linear sequence of nucleotides in DNA. Each molecule of DNA contains two complementary strands of deoxyribonucleotides which contain the purine bases, adenine and guanine and the pyrimidines, cytosine and thymine. RNA is single-stranded, being composed of a linear sequence of ribonucleotides the bases are the same as in DNA with the exception that thymine is replaced by the closely related base uracil. DNA replication occurs by the polymerisation of a new complementary strand on to each of the old strands. 

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