Deoxyribose sugars nucleic acids

Any one nucleotide, the basic building block of a nucleic acid, is derived from a molecule of phosphoric acid, a molecule of a sugar (either deoxyribose or ribose), and a molecule of one of five nitrogen compounds (bases) cytosine (C), thymine (T), adenine (A), guanine (G), uracil (U). 

The sugars are typically ribose (ribonucleic acids, RNA), or 2-deoxyribose (deoxyribonucleic acids, DNA). There are five common bases in nucleic acids adenine (A) thymine (T) uracil (U) cytosine (C) and guanine (G). DNA polymers incorporate the four bases. A, T, C, and G, and RNA, the set A, U, C, and G. 

As is well-known, nucleic acids consist of a polymeric chain of monotonously reiterating molecules of phosphoric acid and a sugar. In ribonucleic acid, the sugar component is represented by n-ribose, in deoxyribonucleic acid by D-2-deoxyribose. To this chain pyrimidine and purine derivatives are bound at the sugar moieties, these derivatives being conventionally, even if inaccurately, termed as pyrimidine and purine bases. The bases in question are uracil (in ribonucleic acids) or thymine (in deoxyribonucleic acids), cytosine, adenine, guanine, in some cases 5-methylcytosine and 5-hydroxymethylcyto-sine. In addition to these, a number of the so-called odd bases occurring in small amounts in some ribonucleic acid fractions have been isolated. 

The nucleic acids DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are biological polymers that act as chemical carriers of an organism s genetic information. Enzyme-catalyzed hydrolysis of nucleic acids yields nucleotides, the monomer units from which RNA and DNA are constructed. Further enzyme-catalyzed hydrolysis of the nucleotides yields nucleosides plus phosphate. Nucleosides, in turn, consist of a purine or pyrimidine base linked to Cl of an aldopentose sugar—ribose in RNA and 2-deoxyribose in DNA. The nucleotides are joined by phosphate links between the 5 phosphate of one nucleotide and the 3 hydroxyl on the sugar of another nucleotide. 

About 40 different sugars are formed. Those required for nucleic acid synthesis, ribose and deoxyribose, are obtained in yields of less than 1%. It is completely unclear whether these could have been separated from the others under primeval Earth conditions (Shapiro, 1988). 

In the two nucleic acids, the sugar component consists solely of D-ribose or D-deoxyribose. 

As discussed in Chap. 6, nucleic acids contain D-ribose or D-deoxyribose. The corresponding L-form is banished from the information carriers RNA and DNA. So the question is why L-amino acids and D-sugars and not the opposite Two hypotheses are at the fore in this scientific discussion ... 

Figure 1.40 The two forms of sugar residues commonly found in nucleic acids. 3-D-Ribose is the sugar constituent of RNA, while p-D-2-deoxyribose is a component of DNA.

The relationship between the DNA in the nucleus and proteins in the cytoplasm is not direct. The information in the DNA molecule is transmitted to the protein-synthesizing machinery of the cell via another informational nucleic acid, called messenger RNA (mRNA), which is synthesized by an enzyme called RNA polymerase. Although similar to DNA, mRNAs are single-stranded, and possess the base uracil instead of thymine and the sugar ribose rather than deoxyribose. These molecules act as short-lived copies of the genes being expressed. 

So far, I have described the primary structure of a nucleic acid. DNA is a linear polynucleotide based on 2 -deoxyribose as sugar and A, Ci C, and T as bases. RNA is a linear polynucleotide based on ribose as sugar and A, G, C, and U as bases. In both... 

A nucleotide consists of a heterocyclic base linked to a sugar (ribose or deoxyribose) and a phosphate group also linked to the sugar (Figure 10.6). Nucleic acids are polymers of nucleotides linked together by phosphodiester bonds (Figure 10.7). The enzymes that catalyse the breakdown of nucleic acids to nucleotides are nucleases. 

Whilst many biochemicals are mono-esters of phosphoric acid, the nucleic acids DNA and RNA (see Section 14.2) provide us with good examples of diesters. A short portion of one strand of a DNA molecule is shown here the most significant difference in RNA is the use of ribose rather than deoxyribose as the sugar unit. 

The bases are either monocyclic pyrimidines or bicyclic purines (see Section 14.1). Three pyrimidine bases are encountered in DNA and RNA, cytosine (C), thymine (T) and uracil (U). Cytosine is common to both DNA and RNA, but uracil is found only in RNA and thymine is found only in DNA. In the nucleic acid, the bases are linked through an A-glycoside bond to a sugar, either ribose or deoxyribose the combination base plus sugar is termed a nucleoside. The nitrogen bonded to the sugar is that shown. 

When a nucleic acid base is N-glycosidically linked to ribose or 2-deoxyribose (see p.38), it yields a nucleoside. The nucleoside adenosine (abbreviation A) is formed in this way from adenine and ribose, for example. The corresponding derivatives of the other bases are called guanosine (G), uridine (U), thymidine (T) and cytidine (C). When the sugar component is 2-deoxyribose, the product is a deoxyribonucleoside—e. g., 2 -deoxyadeno-... 

Nature is also selective in the geometry involved in nucleic acid synthesis. This specificity involves both the base order and the particular sugar employed. For DNA the employed sugar is (3-2-deoxy-D-ribose, deoxyribose (below left). Deoxyribose has three chiral centers but only one of them is employed in the synthesis of nucleic acids. Ribose, the sugar employed in the synthesis of RNA, has four geometric sites (below right). 

Nucleic Acid. A nucleic acid is a natural polynucleotide. It is a sugar-phosphate chain with purine and pyrimidine bases attached to it, as shown in Chart 10. If the sugar is deoxyribose and the pyrimidine bases are cytosine and thymine, the nucleic acid is deoxyribonucleic acid, DNA if the sugar is ribose, and the pyrimidine bases are (mostly) cytosine and uracil, the nucleic acid is ribonucleic acid, RNA. The sequence of bases may appear arbitrary and random, but it constitutes a meaningful code (see Code Word). In double-stranded nucleic acids,... 

In DNA the sugar molecule in the nucleotide is 2-deoxyribose, and in RNA it is ribose. The amine bases in DNA are adenine, thymine, cytosine, and guanine, symbolized by A, T, C, and G, respectively. RNA contains adenine, cytosine, and guanine, but thymine is replaced by the based uracil (Figure 16.16). The primary structure of nucleic acids is given by the sequence of the amine side chains starting from the phosphate end of the nucleotide. For example, a DNA sequence may be -T-A-A-G-C-T. 

The nucleic acids, rna (ribonucleic acid) and dna (deoxyribonucleic acid), are carbohydrate biopolymers. The repeating sugar in rna is ribose, and in dna it is 2-deoxyribose. 

The nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are the chemical carriers of a cell s genetic information. Nucleic acids are biopolymers made of nucleotides joined together to form a long chain. These biopolymers are often found associated with proteins, and in this form they are called nucleoproteins. Each nucleotide comprises a nucleoside bonded to a phosphate group, and each nucleoside is composed of an aldopentose sugar, ribose or 2-deoxyribose, linked to a heterocyclic purine or pyrimidine base (see Section 4.7). 

Tetrahydrofuran is by far the most important of the reduced furans. The compound itself is a major solvent, whilst the nucleus occurs in the ribose and deoxyribose sugar units (as well as in sucrose) and is therefore an integral part of the nucleic acids, RNA and DNA. 

The basic monomers of nucleic acids are nucleotides which are made up of heterocyclic nitrogen-containing compounds, purines and pyrimidines, linked to pentose sugars. There are two types of nucleic acids and these can be distinguished on the basis of the sugar moiety of the molecule, Ribonucleic acids (RNA) contain ribose, while deoxyribonucleic acid (DNA) contains deoxyribose. The bases cytosine (C) adenine (A) and guanine (G) are common in both RNA and DNA. However, RNA molecules contain a unique base, uracil (U), while the unique DNA base is thymidine (T). These differences in the base structure markedly affect the secondary structures of these polymers. The structures of DNA and RNA are outlined in Appendix 5.2. 

The structural components of nucleic acids. Nucleic acids are long linear polymers of nucleotides, called polynucleotides, (a) The nucleotide consists of a five-carbon sugar (ribose in RNA or deoxyribose in DNA) covalently linked at the 5 carbon to a phosphate, and at the 1 carbon to a nitrogenous base. (b) Nucleotides are distinguished by the types of bases they contain. These are either of the two-ring purine type or of the one-ring pyrimidine type. 

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