Nucleotides have a variety of roles in cellular metabolism. They are the energy currency in metabolic transactions, the essential chemical links in the response of cells to hormones and other extracellular stimuli, and the structural components of an array of enzyme cofactors and metabolic intermediates. And, last but certainly not least, they are the constituents of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), the molecular repositories of genetic information. The structure of every protein, and ultimately of every biomolecule and cellular component, is a product of information programmed into the nucleotide sequence of cellular (or viral) nucleic acids. The ability to store and transmit genetic information from one generation to the next is a fundamental condition for life.
The discussion in this chapter reinforces or introduces five principles:
Nucleic acids are both repositories and functional expressions of biological information. Biological information is one of the required conditions for life, a blueprint for each species transmitted from one generation to the next. RNA can be a functional expression of that information, directing the synthesis of proteins or in some cases acting directly as a signal or a reaction catalyst.
The transmission of biological information relies on molecular complementarity. Chromosomes are the largest molecules in any cell. They are polymers composed of a small set of common nucleotides, with information embedded in the nucleotide sequence. The common nucleotides in RNA and DNA are organized so that two strands of nucleic acid can maintain a complementary and uniform structure over vast molecular distances. This extended potential for both variable sequence and complementarity, and thus information storage and transmission, is a property shared by no other class of biological molecule.
Biological information is subject to natural damage and change. DNA damage is a constant, and it results in occasional mutation — the raw material for evolution.
Biological information can be accessed, interpreted, and altered in the laboratory. The information embedded in nucleic acids is of singular importance to biochemistry and molecular biology. The techniques for sequencing, synthesizing, and altering nucleic acids are continually advancing.
Nucleoside triphosphates occupy a central role in cellular metabolism, serving as an energy currency and as important regulatory signals. ATP is the ultimate product of catabolic pathways, providing fuel for anabolic pathways.
This chapter provides an overview of the chemical nature of the nucleotides and nucleic acids found in most cells, as well as the tools used to study them. A more detailed examination of the function of nucleic acids is the focus of Part III of this text.
Nucleic acids are both repositories and functional expressions of biological information. Biological information is one of the required conditions for life, a blueprint for each species transmitted from one generation to the next. RNA can be a functional expression of that information, directing the synthesis of proteins or in some cases acting directly as a signal or a reaction catalyst.
The transmission of biological information relies on molecular complementarity. Chromosomes are the largest molecules in any cell. They are polymers composed of a small set of common nucleotides, with information embedded in the nucleotide sequence. The common nucleotides in RNA and DNA are organized so that two strands of nucleic acid can maintain a complementary and uniform structure over vast molecular distances. This extended potential for both variable sequence and complementarity, and thus information storage and transmission, is a property shared by no other class of biological molecule.
Biological information is subject to natural damage and change. DNA damage is a constant, and it results in occasional mutation — the raw material for evolution.
Biological information can be accessed, interpreted, and altered in the laboratory. The information embedded in nucleic acids is of singular importance to biochemistry and molecular biology. The techniques for sequencing, synthesizing, and altering nucleic acids are continually advancing.
Nucleoside triphosphates occupy a central role in cellular metabolism, serving as an energy currency and as important regulatory signals. ATP is the ultimate product of catabolic pathways, providing fuel for anabolic pathways.