Nucleic acids genetic information transmission

Nucleic acids are acidic substances present m the nuclei of cells and were known long before anyone suspected they were the primary substances involved m the storage transmission and processing of genetic information There are two kinds of nucleic acids ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) Both are complicated biopolymers based on three structural units a carbohydrate a phosphate ester linkage between carbohydrates and a heterocyclic aromatic compound The heterocyclic aro matic compounds are referred to as purine and pyrimidine bases We 11 begin with them and follow the structural thread... 

NUCLEOPROTEINS. Nucleoprotein conjugates have many roles in the storage and transmission of genetic information. Ribosomes are the sites of protein synthesis. Virus particles and even chromosomes are protein-nucleic acid complexes. 

What are the facts of life One of the most striking is that all known living systems involve the same types of polymers, i.e., three varieties of homochiral biopolymers. That is, each variety is composed of unique molecular building blocks having the same three-dimensional handedness. Thus, with rare exceptions, the proteins found in cells are composed exclusively of the 1-enantiomers of 19 optically active amino acids (Fig. 11.1). Similarly, only D-ribose and 2-deoxy-D-ribose sugars are found in the nucleic acid polymers that make up the RNAs and DNAs, which are essential for protein synthesis in the cell and for the transmission of genetic information from one generation to the next. 

The two major classes of nucleic acids are ribonucleic acids (RNA) and deoxyribonucleic acids (DNA). In a typical cell, DNA is found primarily in the nucleus, where it carries the permanent genetic code. The molecules of DNA are huge, with molecular weights up to 50 billion. When the cell divides, DNA replicates to form two copies for the daughter cells. DNA is relatively stable, providing a medium for transmission of genetic information from one generation to the next. 

The major nucleic acid in the nucleus of cells is deoxyribonucleic add (or DNA). It contains the pentose sugar deoxyribose as one of its chemical constituents. DNA is now known to be the genetic material. Another type of nucleic acid, ribonucleic acid (or RNA), contains ribose instead of deoxyribose. Its main role is in the transmission of the genetic information from DNA into protein. 

Recently a field of science called Life Science has been developed and its further development as a synthetic science which is related to a wide range of scientific fields is expected in the future. The aim of life science is to investigate the structure and properties of biomolecules that govern life activity, to elucidate the mechanism of the reactions of biomolecules, and to utilize the aspects of biomolecules for reactions in vitro. There are a number of polymeric compounds in vivo, such as proteins, that are related directly to life phenomena and nucleic acids that control the transmission of genetic information. To understand the functionality of these biopdymers and to exploit useful functional materials, an investigation on Biologically Important Polymers should be based on polymer chenustry. 

In biological systems, proteins and nucleic acids perform two major roles metabolism and conversion of materials and the storage and transmission of genetic information. Proteins are synthesized according to programs written in DNA, while nucleic acid replication and repair both require protein functionality. Proteins and nucleic acids needs each other - they are interdependent. 

Single-stranded nucleic acids often fold back on themselves to form well-defined structures. Early in evolutionary history, nucleic acids, particularly RNA, may have adopted complex and diverse structures both to store genetic information and to catalyze its transmission (Section 2.2.2). Such structures are also important in all modem organisms in entities such as the ribosome, a large complex of RNAs and proteins on which proteins are synthesized. 

The transmission of genetic information requires accmate base pairing between nucleic acids. This includes translation of mRNA into protein by the ribosome on which accurate selection of aa-tRNA depends upon the correct pairing of three bases between the mRNA codon and the tRNA anticodon. For example, the codon-anticodon mismatches are efficiently rejected with error frequencies as low as 10. Plausible mechanisms for the involvement of the ribosome in the decoding of mRNA codon tRNA anticodon (Ogle et al, 2003 Rodnina and Wintermeyer, 2001) include ... 

The many functions of proteins, polysaccharides and lipids include energy storage and as structural building units, while nucleic acids are responsible for the storage, transmission and translation of genetic information. All nucleic acids and several kinds of lipids contain phosphorus, while most varieties of proteins either contain phosphorus or are closely associated with phosphorus compounds in some way or another (Chapter 10). About half the presently known proteins will bind and/ or process compounds containing phosphoryl groups. 

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