An overview of Nucleic acid sequence
Nucleic acid sequence is a series of letters showing the order of nucleotides in a DNA or RNA molecule. Conventionally, representation of these sequences is by 5′ end to the 3′ end. The sense strand is used in DNA. Nucleic acids are linear polymers. This means that specifying its sequence is the same identifying the covalent arrangement of the whole structure. Thus, nucleic acid sequence is also known as primary structure.
This sequence is important since it can represent information. Biological DNA carries information that determines functions of plants and animals. In such cases, genetic sequence is commonly used. Reading of sequences can be done on biological raw material via DNA sequencing approaches. Besides primary structures, nucleic acids also have secondary and tertiary structures.
Nucleotides and Nucleic Acid Sequence
Nucleotides are chains of linked units, which occur in nucleic acids. A nucleotide has three subunits. A phosphate group and a sugar form the basis of the nucleic acid strand with one of the nucleobases attached to the sugar. Nucleobases serve as essential elements in base pairing of strands in the formation of secondary and tertiary structures equivalent to the double helix, synonymous with the DNA structure.
The four-nucleotide bases found in DNA are adenine, cytosine, guanine, and thymine, denoted by letters A, C, G, and T, respectively. These bases are covalently attached to a phosphodiester backbone. During transcription, a sequence is said to be on the coding strand if its order matches with the transcribed RNA. An important attribute of nucleic acid sequence is that a sequence can be complementary to another. This implies they have the base in each complementary position.
Biosynthesis and Degradation
Readily available precursors are the materials from which nucleotides develop in the cell. The ribose phosphate of purine and pyrimidine nucleotides comes from glucose through the pentose phosphate route. First, to be synthesized is the six-atom pyrimidine ring before it attaches to the ribose phosphate. When adenine or guanine nucleotides are being assembled, the two rings in purine form when it is still cleaved to the ribose phosphate. The product in both cases is a nucleotide that has a phosphate group on the fifth carbon in the sugar chain.
At the final stage of the synthesis, kinase, a specialized enzyme, attaches two phosphate groups with the aid of adenosine triphosphate, ATP to generate ribonucleoside triphosphate, which acts as the immediate precursor or RNA. In the case of DNA, 2′-hydroxyl is eliminated from the ribonucleoside diphosphate to form deoxyribonucleoside diphosphate. Another phosphate group adds from ATP with the help of kinase to give a deoxyribonucleoside triphosphate. This becomes the immediate precursor of DNA, which becomes part of the nucleic acid sequence.
Significance of nucleic acid sequence
Nucleic acids play a major role in living things. For example, they contain information, which a cell needs during the synthesis particular proteins. During this process, the cell machinery translates the sequence of nucleobases into a sequence of amino acids, which form the protein strand. In this case, a single group of the three bases, also known as codon is equivalent to a single amino acid.
The sequence also has application in the central dogma of molecular biology where the synthesis of proteins occurs with the aid of instructions from nucleic acids. Here, transcription takes place, allowing DNA to form mRNA molecules, which moves to the ribosome and acts as an outline during the building of the protein strand.
Moreover, nucleic acid sequence essential in living things because it permits encoding of information that is crucial for the survival and reproduction of the living thing. Thus, determining this sequence is vital in research as it helps in the understanding of why and how plants and animals live and in applied subjects. Furthermore, because of the relevance of DNA information in living things, determining this sequence can offer a wide range of insights into practical and biological research. For example, it can be applied in medicine for the identification, diagnosis, and help in treatment of genetic diseases. It also has massive application in biotechnology, as a growing field.
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References:
http://www.chem.qmul.ac.uk/iubmb/misc/naseq.html
http://www.britannica.com/science/nucleic-acid
http://www.nature.com/scitable/topicpage/the-order-of-nucleotides-in-a-gene-6525806
http://www2.le.ac.uk/departments/genetics/vgec/schoolscolleges/topics/geneexpression-regulation