Nucleic Acid Synthesis

Important Terms (Nucleic Acid Synthesis)

Cell cycle Stages in the life cycle of replicating eukaryotic cells. After cell division (mitosis), a cell goes through the resting G1/Go phase prior to DNA replication in the S phase. Completion of duplication of cellular materials in the G2 phase occurs prior to mitosis (M phase). Chromatin Cellular genome as nucleoprotein which contains DNA, […]

Nucleic Acid Synthesis

NUCLEIC ACIDS are involved in the most fundamental processes of life. Their maintenance and production are essential in all living organisms. The hallmark of the biosphere is diversity of biological processes, even among members of the same genera, e.g., bacteria. Each organism may have some unique features in regard to nucleic acid composition, structure, and […]

STRUCTURE AND FUNCTION OF NUCLEIC ACIDS

A. Basic Chemical Structure The basic information for all activities in living systems, at least on our planet, is stored ultimately in nucleic acids, namely, deoxyribonucleic (DNA) and ribonucleic (RNA) acids. Except for certain viruses, DNA is the universal genetic material (Fig. 1). The chemical structures of basic units of RNA and DNA have been […]

NUCLEIC ACID SYNTHESES

A. Similarity of DNA and RNA Synthesis All nucleic acids are usually synthesized by DNA template-guided polymerization of nucleotides—ribonucleotides for RNA and deoxy(ribo)nucleotides for DNA. The reactant monomers are 5′ ribonucleoside (or deoxyri-bonucleoside) triphosphates. These can be described in the following chemical equations: and Enzymatic polymerization is carried out by DNA and RNA polymerases, both […]

DNA REPLICATION AND ITS REGULATION (Nucleic Acid Synthesis)

A. DNA Replication DA replication is initiated at discrete sequences called origin (ori) of replication to which DNA polymerase and accessory proteins bind and copy both strands, as predicted by the semi-conservative replication model (Fig. 2B). In contrast to unidirectional RNA synthesis, DNA replication in most genomes occurs bidirectionally (Fig. 2B). This results in both […]

MAINTENANCE OF GENOME INTEGRITY (Nucleic Acid Synthesis)

The integrity of the genome, both in regard to sequence and to size, is essential for perpetuation of species. This integrity can be threatened in two ways. The first is by errors in DNA replication, as discussed earlier. A second inexorable process of DNA alteration occurs due to chemical reactions which can be either endogenous […]

DNA MANIPULATIONS AND THEIR APPLICATIONS (Nucleic Acid Synthesis)

A. Episomal DNA and Recombinant DNA Technology Extrachromosomal or episomal DNA, present in prokary-otes and lower eukaryotes, is distinct from the genome of organelles such as mitochondria or chloroplasts and serves many purposes. In bacteria, plasmid DNA can be transmitted to progeny cells, and the genes in these plas-mids encode distinct proteins which provide growth […]

TRANSCRIPTIONAL PROCESSES (Nucleic Acid Synthesis)

Transcription is a highly complex process because of its defined initiation and termination sites in the genome and the subsequent processing and regulation of its synthesis. The steady-state level of a protein in the cell is the balance of its rate of synthesis and degradation. The synthesis is determined primarily by the steady-state level of […]

CHEMICAL SYNTHESIS OF NUCLEIC ACIDS (OLIGONUCLEOTIDES)

Development of strategies for chemical synthesis of nucleic acids represented a major breakthrough in molecular biology, because most of the current approaches involving PCR, manipulation of recombinant DNA, studies of gene regulation, etc. require synthetic DNA and RNA oligonu-cleotides with defined sequences. The difficulty of synthesizing RNA and DNA polynucleotide chains from mononucleotide units lies […]