The word "nucleotide sequence" is commonly used in molecular biology to describe the order of nucleotides in a DNA or RNA molecule. The IPA phonetic transcription of this word is /ˈnjuːkliətaɪd ˈsiːkwəns/. In this transcription, the stress is on the second syllable of "nucleotide" and the first syllable of "sequence." The first two letters of "nucleotide" are pronounced as "nu," rather than "new." The "ti" in "nucleotide" has a soft "sh" sound. The "s" in "sequence" is pronounced as "suh," rather than "see."
A nucleotide sequence refers to the specific arrangement or order of nucleotides in a nucleic acid molecule. Nucleotides are the building blocks of DNA and RNA, the two types of nucleic acids present in living organisms. Each nucleotide consists of three components: a phosphate group, a sugar molecule (deoxyribose in DNA or ribose in RNA), and a nitrogenous base. The nitrogenous bases in DNA include adenine (A), cytosine (C), guanine (G), and thymine (T), while RNA contains uracil (U) instead of thymine.
A nucleotide sequence provides the fundamental information that encodes genetic instructions and serves as the basis for genetic variation. In DNA, nucleotides are arranged in a linear manner to form a double-stranded helical structure, with A always pairing with T and C always pairing with G. This complementary base pairing allows DNA replication, transcription, and translation processes to occur, enabling the transmission and expression of genetic information. Similarly, in RNA, nucleotides form single-stranded molecules that aid in gene expression, protein synthesis, and other cellular processes.
The determination and analysis of nucleotide sequences have contributed profoundly to fields such as genetics, genomics, and molecular biology. Techniques like DNA sequencing are used to determine the precise order of nucleotides in a DNA molecule, providing crucial insights into the structure and function of genes and genomes. Nucleotide sequence data are also extensively used in bioinformatics and comparative genomics to investigate evolutionary relationships, study genetic diseases, design therapeutic interventions, and explore the vast complexities of living organisms at the molecular level.
The word "nucleotide" comes from the Latin term "nucleus", meaning "kernel" or "core", and the suffix "-ide", which is used in chemistry to denote a particular type of compound. In this case, nucleotides are compounds that serve as the building blocks of nucleic acids such as DNA or RNA.
The word "sequence" comes from the Latin term "sequi", meaning "to follow" or "to pursue". It refers to the arrangement or order of something, particularly in a continuous or successive manner.
Therefore, the term "nucleotide sequence" combines these two elements, indicating the ordered arrangement or succession of nucleotides in a DNA or RNA molecule.