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Bioinformatics
Bioinformatics
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Early bioinformatics—computational alignment of experimentally determined sequences of a class of related proteins; see § Sequence analysis for further information.
Map of the human X chromosome (from the National Center for Biotechnology Information (NCBI) website)

Bioinformatics (/ˌb.ˌɪnfərˈmætɪks/ ) is an interdisciplinary field of science that develops methods and software tools for understanding biological data, especially when the data sets are large and complex. Bioinformatics uses biology, chemistry, physics, computer science, data science, computer programming, information engineering, mathematics and statistics to analyze and interpret biological data. This process can sometimes be referred to as computational biology, however the distinction between the two terms is often disputed. To some, the term computational biology refers to building and using models of biological systems.

Computational, statistical, and computer programming techniques have been used for computer simulation analyses of biological queries. They include reused specific analysis "pipelines", particularly in the field of genomics, such as by the identification of genes and single nucleotide polymorphisms (SNPs). These pipelines are used to better understand the genetic basis of disease, unique adaptations, desirable properties (especially in agricultural species), or differences between populations. Bioinformatics also includes proteomics, which aims to understand the organizational principles within nucleic acid and protein sequences.[1]

Image and signal processing allow extraction of useful results from large amounts of raw data. It aids in sequencing and annotating genomes and their observed mutations. Bioinformatics includes text mining of biological literature and the development of biological and gene ontologies to organize and query biological data. It also plays a role in the analysis of gene and protein expression and regulation. Bioinformatic tools aid in comparing, analyzing, interpreting genetic and genomic data and in the understanding of evolutionary aspects of molecular biology. At a more integrative level, it helps analyze and catalogue the biological pathways and networks that are an important part of systems biology. In structural biology, it aids in the simulation and modeling of DNA,[2] RNA,[2][3] proteins[4] as well as biomolecular interactions.[5][6][7][8]

History

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The first definition of the term bioinformatics was coined by Paulien Hogeweg and Ben Hesper in 1970, to refer to the study of information processes in biotic systems.[9][10][11][12][13] This definition placed bioinformatics as a field parallel to biochemistry (the study of chemical processes in biological systems).[10]

Bioinformatics and computational biology involved the analysis of biological data, particularly DNA, RNA, and protein sequences. The field of bioinformatics experienced explosive growth starting in the mid-1990s, driven largely by the Human Genome Project and by rapid advances in DNA sequencing technology.[citation needed]

Analyzing biological data to produce meaningful information involves writing and running software programs that use algorithms from graph theory, artificial intelligence, soft computing, data mining, image processing, and computer simulation. The algorithms in turn depend on theoretical foundations such as discrete mathematics, control theory, system theory, information theory, and statistics.[citation needed]

Sequences

[edit]
Sequences of genetic material are frequently used in bioinformatics and are easier to manage using computers than manually.
These are sequences being compared in a MUSCLE multiple sequence alignment (MSA). Each sequence name (leftmost column) is from various louse species, while the sequences themselves are in the second column.

There has been a tremendous advance in speed and cost reduction since the completion of the Human Genome Project, with some labs able to sequence over 100,000 billion bases each year, and a full genome can be sequenced for $1,000 or less.[14]

Computers became essential in molecular biology when protein sequences became available after Frederick Sanger determined the sequence of insulin in the early 1950s.[15][16] Comparing multiple sequences manually turned out to be impractical. Margaret Oakley Dayhoff, a pioneer in the field,[17] compiled one of the first protein sequence databases, initially published as books[18] as well as methods of sequence alignment and molecular evolution.[19] Another early contributor to bioinformatics was Elvin A. Kabat, who pioneered biological sequence analysis in 1970 with his comprehensive volumes of antibody sequences released online with Tai Te Wu between 1980 and 1991.[20]

In the 1970s, new techniques for sequencing DNA were applied to bacteriophage MS2 and øX174, and the extended nucleotide sequences were then parsed with informational and statistical algorithms. These studies illustrated that well known features, such as the coding segments and the triplet code, are revealed in straightforward statistical analyses and were the proof of the concept that bioinformatics would be insightful.[21][22]

Goals

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In order to study how normal cellular activities are altered in different disease states, raw biological data must be combined to form a comprehensive picture of these activities. Therefore[when?], the field of bioinformatics has evolved such that the most pressing task now involves the analysis and interpretation of various types of data. This also includes nucleotide and amino acid sequences, protein domains, and protein structures.[23]

Important sub-disciplines within bioinformatics and computational biology include:

  • Development and implementation of computer programs to efficiently access, manage, and use various types of information.
  • Development of new mathematical algorithms and statistical measures to assess relationships among members of large data sets. For example, there are methods to locate a gene within a sequence, to predict protein structure and/or function, and to cluster protein sequences into families of related sequences.

The primary goal of bioinformatics is to increase the understanding of biological processes. What sets it apart from other approaches is its focus on developing and applying computationally intensive techniques to achieve this goal. Examples include: pattern recognition, data mining, machine learning algorithms, and visualization. Major research efforts in the field include sequence alignment, gene finding, genome assembly, drug design, drug discovery, protein structure alignment, protein structure prediction, prediction of gene expression and protein–protein interactions, genome-wide association studies, the modeling of evolution and cell division/mitosis.

Bioinformatics entails the creation and advancement of databases, algorithms, computational and statistical techniques, and theory to solve formal and practical problems arising from the management and analysis of biological data.

Over the past few decades, rapid developments in genomic and other molecular research technologies and developments in information technologies have combined to produce a tremendous amount of information related to molecular biology. Bioinformatics is the name given to these mathematical and computing approaches used to glean understanding of biological processes.

Common activities in bioinformatics include mapping and analyzing DNA and protein sequences, aligning DNA and protein sequences to compare them, and creating and viewing 3-D models of protein structures.

Sequence analysis

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Since the bacteriophage Phage Φ-X174 was sequenced in 1977,[24] the DNA sequences of thousands of organisms have been decoded and stored in databases. This sequence information is analyzed to determine genes that encode proteins, RNA genes, regulatory sequences, structural motifs, and repetitive sequences. A comparison of genes within a species or between different species can show similarities between protein functions, or relations between species (the use of molecular systematics to construct phylogenetic trees). With the growing amount of data, it long ago became impractical to analyze DNA sequences manually. Computer programs such as BLAST are used routinely to search sequences—as of 2008, from more than 260,000 organisms, containing over 190 billion nucleotides.[25]

DNA sequencing

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Before sequences can be analyzed, they are obtained from a data storage bank, such as GenBank. DNA sequencing is still a non-trivial problem as the raw data may be noisy or affected by weak signals. Algorithms have been developed for base calling for the various experimental approaches to DNA sequencing.

Image: 450 pixels Sequencing analysis steps
Image: 450 pixels Sequencing analysis steps

Sequence assembly

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Most DNA sequencing techniques produce short fragments of sequence that need to be assembled to obtain complete gene or genome sequences. The shotgun sequencing technique (used by The Institute for Genomic Research (TIGR) to sequence the first bacterial genome, Haemophilus influenzae)[26] generates the sequences of many thousands of small DNA fragments (ranging from 35 to 900 nucleotides long, depending on the sequencing technology). The ends of these fragments overlap and, when aligned properly by a genome assembly program, can be used to reconstruct the complete genome. Shotgun sequencing yields sequence data quickly, but the task of assembling the fragments can be quite complicated for larger genomes. For a genome as large as the human genome, it may take many days of CPU time on large-memory, multiprocessor computers to assemble the fragments, and the resulting assembly usually contains numerous gaps that must be filled in later. Shotgun sequencing is the method of choice for virtually all genomes sequenced (rather than chain-termination or chemical degradation methods), and genome assembly algorithms are a critical area of bioinformatics research.

Genome annotation

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In genomics, annotation refers to the process of marking the stop and start regions of genes and other biological features in a sequenced DNA sequence. Many genomes are too large to be annotated by hand. As the rate of sequencing exceeds the rate of genome annotation, genome annotation has become the new bottleneck in bioinformatics.[when?]

Genome annotation can be classified into three levels: the nucleotide, protein, and process levels.

Gene finding is a chief aspect of nucleotide-level annotation. For complex genomes, a combination of ab initio gene prediction and sequence comparison with expressed sequence databases and other organisms can be successful. Nucleotide-level annotation also allows the integration of genome sequence with other genetic and physical maps of the genome.

The principal aim of protein-level annotation is to assign function to the protein products of the genome. Databases of protein sequences and functional domains and motifs are used for this type of annotation. About half of the predicted proteins in a new genome sequence tend to have no obvious function.

Understanding the function of genes and their products in the context of cellular and organismal physiology is the goal of process-level annotation. An obstacle of process-level annotation has been the inconsistency of terms used by different model systems. The Gene Ontology Consortium is helping to solve this problem.[27]

The first description of a comprehensive annotation system was published in 1995[26] by The Institute for Genomic Research, which performed the first complete sequencing and analysis of the genome of a free-living (non-symbiotic) organism, the bacterium Haemophilus influenzae.[26] The system identifies the genes encoding all proteins, transfer RNAs, ribosomal RNAs, in order to make initial functional assignments. The GeneMark program trained to find protein-coding genes in Haemophilus influenzae is constantly changing and improving.

Following the goals that the Human Genome Project left to achieve after its closure in 2003, the ENCODE project was developed by the National Human Genome Research Institute. This project is a collaborative data collection of the functional elements of the human genome that uses next-generation DNA-sequencing technologies and genomic tiling arrays, technologies able to automatically generate large amounts of data at a dramatically reduced per-base cost but with the same accuracy (base call error) and fidelity (assembly error).

Gene function prediction

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While genome annotation is primarily based on sequence similarity (and thus homology), other properties of sequences can be used to predict the function of genes. In fact, most gene function prediction methods focus on protein sequences as they are more informative and more feature-rich. For instance, the distribution of hydrophobic amino acids predicts transmembrane segments in proteins. However, protein function prediction can also use external information such as gene (or protein) expression data, protein structure, or protein–protein interactions.[28]

Computational evolutionary biology

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Evolutionary biology is the study of the origin and descent of species, as well as their change over time. Informatics has assisted evolutionary biologists by enabling researchers to:

  • trace the evolution of a large number of organisms by measuring changes in their DNA, rather than through physical taxonomy or physiological observations alone,
  • compare entire genomes, which permits the study of more complex evolutionary events, such as gene duplication, horizontal gene transfer, and the prediction of factors important in bacterial speciation,
  • build complex computational population genetics models to predict the outcome of the system over time[29]
  • track and share information on an increasingly large number of species and organisms

Comparative genomics

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The core of comparative genome analysis is the establishment of the correspondence between genes (orthology analysis) or other genomic features in different organisms. Intergenomic maps are made to trace the evolutionary processes responsible for the divergence of two genomes. A multitude of evolutionary events acting at various organizational levels shape genome evolution. At the lowest level, point mutations affect individual nucleotides. At a higher level, large chromosomal segments undergo duplication, lateral transfer, inversion, transposition, deletion and insertion.[30] Entire genomes are involved in processes of hybridization, polyploidization and endosymbiosis that lead to rapid speciation. The complexity of genome evolution poses many exciting challenges to developers of mathematical models and algorithms, who have recourse to a spectrum of algorithmic, statistical and mathematical techniques, ranging from exact, heuristics, fixed parameter and approximation algorithms for problems based on parsimony models to Markov chain Monte Carlo algorithms for Bayesian analysis of problems based on probabilistic models.

Many of these studies are based on the detection of sequence homology to assign sequences to protein families.[31]

Pan genomics

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Pan genomics is a concept introduced in 2005 by Tettelin and Medini. Pan genome is the complete gene repertoire of a particular monophyletic taxonomic group. Although initially applied to closely related strains of a species, it can be applied to a larger context like genus, phylum, etc. It is divided in two parts: the Core genome, a set of genes common to all the genomes under study (often housekeeping genes vital for survival), and the Dispensable/Flexible genome: a set of genes not present in all but one or some genomes under study. A bioinformatics tool BPGA can be used to characterize the Pan Genome of bacterial species.[32]

Genetics of disease

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As of 2013, the existence of efficient high-throughput next-generation sequencing technology allows for the identification of cause many different human disorders. Simple Mendelian inheritance has been observed for over 3,000 disorders that have been identified at the Online Mendelian Inheritance in Man database, but complex diseases are more difficult. Association studies have found many individual genetic regions that individually are weakly associated with complex diseases (such as infertility,[33] breast cancer[34] and Alzheimer's disease[35]), rather than a single cause.[36][37] There are currently many challenges to using genes for diagnosis and treatment, such as how we don't know which genes are important, or how stable the choices an algorithm provides.[38]

Genome-wide association studies have successfully identified thousands of common genetic variants for complex diseases and traits; however, these common variants only explain a small fraction of heritability.[39] Rare variants may account for some of the missing heritability.[40] Large-scale whole genome sequencing studies have rapidly sequenced millions of whole genomes, and such studies have identified hundreds of millions of rare variants.[41] Functional annotations predict the effect or function of a genetic variant and help to prioritize rare functional variants, and incorporating these annotations can effectively boost the power of genetic association of rare variants analysis of whole genome sequencing studies.[42] Some tools have been developed to provide all-in-one rare variant association analysis for whole-genome sequencing data, including integration of genotype data and their functional annotations, association analysis, result summary and visualization.[43][44] Meta-analysis of whole genome sequencing studies provides an attractive solution to the problem of collecting large sample sizes for discovering rare variants associated with complex phenotypes.[45]

Analysis of mutations in cancer

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In cancer, the genomes of affected cells are rearranged in complex or unpredictable ways. In addition to single-nucleotide polymorphism arrays identifying point mutations that cause cancer, oligonucleotide microarrays can be used to identify chromosomal gains and losses (called comparative genomic hybridization). These detection methods generate terabytes of data per experiment.[46] The data is often found to contain considerable variability, or noise, and thus Hidden Markov model and change-point analysis methods are being developed to infer real copy number changes.[47]

Two important principles can be used to identify cancer by mutations in the exome. First, cancer is a disease of accumulated somatic mutations in genes. Second, cancer contains driver mutations which need to be distinguished from passengers.[48]

Further improvements in bioinformatics could allow for classifying types of cancer by analysis of cancer driven mutations in the genome. Furthermore, tracking of patients while the disease progresses may be possible in the future with the sequence of cancer samples. Another type of data that requires novel informatics development is the analysis of lesions found to be recurrent among many tumors.[49]

Gene and protein expression

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Analysis of gene expression

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The expression of many genes can be determined by measuring mRNA levels with multiple techniques including microarrays, expressed cDNA sequence tag (EST) sequencing, serial analysis of gene expression (SAGE) tag sequencing, massively parallel signature sequencing (MPSS), RNA-Seq, also known as "Whole Transcriptome Shotgun Sequencing" (WTSS), or various applications of multiplexed in-situ hybridization. All of these techniques are extremely noise-prone and/or subject to bias in the biological measurement, and a major research area in computational biology involves developing statistical tools to separate signal from noise in high-throughput gene expression studies.[50] Such studies are often used to determine the genes implicated in a disorder: one might compare microarray data from cancerous epithelial cells to data from non-cancerous cells to determine the transcripts that are up-regulated and down-regulated in a particular population of cancer cells.

MIcroarray vs RNA-Seq

Analysis of protein expression

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Protein microarrays and high throughput (HT) mass spectrometry (MS) can provide a snapshot of the proteins present in a biological sample. The former approach faces similar problems as with microarrays targeted at mRNA, the latter involves the problem of matching large amounts of mass data against predicted masses from protein sequence databases, and the complicated statistical analysis of samples when multiple incomplete peptides from each protein are detected. Cellular protein localization in a tissue context can be achieved through affinity proteomics displayed as spatial data based on immunohistochemistry and tissue microarrays.[51]

Analysis of regulation

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Gene regulation is a complex process where a signal, such as an extracellular signal such as a hormone, eventually leads to an increase or decrease in the activity of one or more proteins. Bioinformatics techniques have been applied to explore various steps in this process.

For example, gene expression can be regulated by nearby elements in the genome. Promoter analysis involves the identification and study of sequence motifs in the DNA surrounding the protein-coding region of a gene. These motifs influence the extent to which that region is transcribed into mRNA. Enhancer elements far away from the promoter can also regulate gene expression, through three-dimensional looping interactions. These interactions can be determined by bioinformatic analysis of chromosome conformation capture experiments.

Expression data can be used to infer gene regulation: one might compare microarray data from a wide variety of states of an organism to form hypotheses about the genes involved in each state. In a single-cell organism, one might compare stages of the cell cycle, along with various stress conditions (heat shock, starvation, etc.). Clustering algorithms can be then applied to expression data to determine which genes are co-expressed. For example, the upstream regions (promoters) of co-expressed genes can be searched for over-represented regulatory elements. Examples of clustering algorithms applied in gene clustering are k-means clustering, self-organizing maps (SOMs), hierarchical clustering, and consensus clustering methods.

Analysis of cellular organization

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Several approaches have been developed to analyze the location of organelles, genes, proteins, and other components within cells. A gene ontology category, cellular component, has been devised to capture subcellular localization in many biological databases.

Microscopy and image analysis

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Microscopic pictures allow for the location of organelles as well as molecules, which may be the source of abnormalities in diseases.

Protein localization

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Finding the location of proteins allows us to predict what they do. This is called protein function prediction. For instance, if a protein is found in the nucleus it may be involved in gene regulation or splicing. By contrast, if a protein is found in mitochondria, it may be involved in respiration or other metabolic processes. There are well developed protein subcellular localization prediction resources available, including protein subcellular location databases, and prediction tools.[52][53]

Nuclear organization of chromatin

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Data from high-throughput chromosome conformation capture experiments, such as Hi-C (experiment) and ChIA-PET, can provide information on the three-dimensional structure and nuclear organization of chromatin. Bioinformatic challenges in this field include partitioning the genome into domains, such as Topologically Associating Domains (TADs), that are organised together in three-dimensional space.[54]

Structural bioinformatics

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3-dimensional protein structures such as this one are common subjects in bioinformatic analyses.

Finding the structure of proteins is an important application of bioinformatics. The Critical Assessment of Protein Structure Prediction (CASP) is an open competition where worldwide research groups submit protein models for evaluating unknown protein models.[55][56]

Amino acid sequence

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The linear amino acid sequence of a protein is called the primary structure. The primary structure can be easily determined from the sequence of codons on the DNA gene that codes for it. In most proteins, the primary structure uniquely determines the 3-dimensional structure of a protein in its native environment. An exception is the misfolded prion protein involved in bovine spongiform encephalopathy. This structure is linked to the function of the protein. Additional structural information includes the secondary, tertiary and quaternary structure. A viable general solution to the prediction of the function of a protein remains an open problem. Most efforts have so far been directed towards heuristics that work most of the time.[citation needed]

Homology

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In the genomic branch of bioinformatics, homology is used to predict the function of a gene: if the sequence of gene A, whose function is known, is homologous to the sequence of gene B, whose function is unknown, one could infer that B may share A's function. In structural bioinformatics, homology is used to determine which parts of a protein are important in structure formation and interaction with other proteins. Homology modeling is used to predict the structure of an unknown protein from existing homologous proteins.

One example of this is hemoglobin in humans and the hemoglobin in legumes (leghemoglobin), which are distant relatives from the same protein superfamily. Both serve the same purpose of transporting oxygen in the organism. Although both of these proteins have very different amino acid sequences, their protein structures are very similar, reflecting their shared function and shared ancestor.[57]

Other techniques for predicting protein structure include protein threading and de novo (from scratch) physics-based modeling.

Another aspect of structural bioinformatics include the use of protein structures for Virtual Screening models such as Quantitative Structure-Activity Relationship models and proteochemometric models (PCM). Furthermore, a protein's crystal structure can be used in simulation of for example ligand-binding studies and in silico mutagenesis studies.

A 2021 deep-learning algorithms-based software called AlphaFold, developed by Google's DeepMind, greatly outperforms all other prediction software methods,[58][how?] and has released predicted structures for hundreds of millions of proteins in the AlphaFold protein structure database.[59]

Network and systems biology

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Network analysis seeks to understand the relationships within biological networks such as metabolic or protein–protein interaction networks. Although biological networks can be constructed from a single type of molecule or entity (such as genes), network biology often attempts to integrate many different data types, such as proteins, small molecules, gene expression data, and others, which are all connected physically, functionally, or both.

Systems biology involves the use of computer simulations of cellular subsystems (such as the networks of metabolites and enzymes that comprise metabolism, signal transduction pathways and gene regulatory networks) to both analyze and visualize the complex connections of these cellular processes. Artificial life or virtual evolution attempts to understand evolutionary processes via the computer simulation of simple (artificial) life forms.

Molecular interaction networks

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Interactions between proteins are frequently visualized and analyzed using networks. This network is made up of protein–protein interactions from Treponema pallidum, the causative agent of syphilis and other diseases.[60]

Tens of thousands of three-dimensional protein structures have been determined by X-ray crystallography and protein nuclear magnetic resonance spectroscopy (protein NMR) and a central question in structural bioinformatics is whether it is practical to predict possible protein–protein interactions only based on these 3D shapes, without performing protein–protein interaction experiments. A variety of methods have been developed to tackle the protein–protein docking problem, though it seems that there is still much work to be done in this field.

Other interactions encountered in the field include Protein–ligand (including drug) and protein–peptide. Molecular dynamic simulation of movement of atoms about rotatable bonds is the fundamental principle behind computational algorithms, termed docking algorithms, for studying molecular interactions.

Biodiversity informatics

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Biodiversity informatics deals with the collection and analysis of biodiversity data, such as taxonomic databases, or microbiome data. Examples of such analyses include phylogenetics, niche modelling, species richness mapping, DNA barcoding, or species identification tools. A growing area is also macro-ecology, i.e. the study of how biodiversity is connected to ecology and human impact, such as climate change.

Others

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Literature analysis

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The enormous number of published literature makes it virtually impossible for individuals to read every paper, resulting in disjointed sub-fields of research. Literature analysis aims to employ computational and statistical linguistics to mine this growing library of text resources. For example:

  • Abbreviation recognition – identify the long-form and abbreviation of biological terms
  • Named-entity recognition – recognizing biological terms such as gene names
  • Protein–protein interaction – identify which proteins interact with which proteins from text

The area of research draws from statistics and computational linguistics.

High-throughput image analysis

[edit]

Computational technologies are used to automate the processing, quantification and analysis of large amounts of high-information-content biomedical imagery. Modern image analysis systems can improve an observer's accuracy, objectivity, or speed. Image analysis is important for both diagnostics and research. Some examples are:

  • high-throughput and high-fidelity quantification and sub-cellular localization (high-content screening, cytohistopathology, Bioimage informatics)
  • morphometrics
  • clinical image analysis and visualization
  • determining the real-time air-flow patterns in breathing lungs of living animals
  • quantifying occlusion size in real-time imagery from the development of and recovery during arterial injury
  • making behavioral observations from extended video recordings of laboratory animals
  • infrared measurements for metabolic activity determination
  • inferring clone overlaps in DNA mapping, e.g. the Sulston score

High-throughput single cell data analysis

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Computational techniques are used to analyse high-throughput, low-measurement single cell data, such as that obtained from flow cytometry. These methods typically involve finding populations of cells that are relevant to a particular disease state or experimental condition.

Ontologies and data integration

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Biological ontologies are directed acyclic graphs of controlled vocabularies. They create categories for biological concepts and descriptions so they can be easily analyzed with computers. When categorised in this way, it is possible to gain added value from holistic and integrated analysis.[citation needed]

The OBO Foundry was an effort to standardise certain ontologies. One of the most widespread is the Gene ontology which describes gene function. There are also ontologies which describe phenotypes.

Databases

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Databases are essential for bioinformatics research and applications. Databases exist for many different information types, including DNA and protein sequences, molecular structures, phenotypes and biodiversity. Databases can contain both empirical data (obtained directly from experiments) and predicted data (obtained from analysis of existing data). They may be specific to a particular organism, pathway or molecule of interest. Alternatively, they can incorporate data compiled from multiple other databases. Databases can have different formats, access mechanisms, and be public or private.

Some of the most commonly used databases are listed below:

Software and tools

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Software tools for bioinformatics include simple command-line tools, more complex graphical programs, and standalone web-services. They are made by bioinformatics companies or by public institutions.

Open-source bioinformatics software

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Many free and open-source software tools have existed and continued to grow since the 1980s.[61] The combination of a continued need for new algorithms for the analysis of emerging types of biological readouts, the potential for innovative in silico experiments, and freely available open code bases have created opportunities for research groups to contribute to both bioinformatics regardless of funding. The open source tools often act as incubators of ideas, or community-supported plug-ins in commercial applications. They may also provide de facto standards and shared object models for assisting with the challenge of bioinformation integration.

Open-source bioinformatics software includes Bioconductor, BioPerl, Biopython, BioJava, BioJS, BioRuby, Bioclipse, EMBOSS, .NET Bio, Orange with its bioinformatics add-on, Apache Taverna, UGENE and GenoCAD.

The non-profit Open Bioinformatics Foundation[61] and the annual Bioinformatics Open Source Conference promote open-source bioinformatics software.[62]

Web services in bioinformatics

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SOAP- and REST-based interfaces have been developed to allow client computers to use algorithms, data and computing resources from servers in other parts of the world. The main advantage are that end users do not have to deal with software and database maintenance overheads.

Basic bioinformatics services are classified by the EBI into three categories: SSS (Sequence Search Services), MSA (Multiple Sequence Alignment), and BSA (Biological Sequence Analysis).[63] The availability of these service-oriented bioinformatics resources demonstrate the applicability of web-based bioinformatics solutions, and range from a collection of standalone tools with a common data format under a single web-based interface, to integrative, distributed and extensible bioinformatics workflow management systems.

Bioinformatics workflow management systems

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A bioinformatics workflow management system is a specialized form of a workflow management system designed specifically to compose and execute a series of computational or data manipulation steps, or a workflow, in a Bioinformatics application. Such systems are designed to

  • provide an easy-to-use environment for individual application scientists themselves to create their own workflows,
  • provide interactive tools for the scientists enabling them to execute their workflows and view their results in real-time,
  • simplify the process of sharing and reusing workflows between the scientists, and
  • enable scientists to track the provenance of the workflow execution results and the workflow creation steps.

Some of the platforms giving this service: Galaxy, Kepler, Taverna, UGENE, Anduril, HIVE.

BioCompute and BioCompute Objects

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In 2014, the US Food and Drug Administration sponsored a conference held at the National Institutes of Health Bethesda Campus to discuss reproducibility in bioinformatics.[64] Over the next three years, a consortium of stakeholders met regularly to discuss what would become BioCompute paradigm.[65] These stakeholders included representatives from government, industry, and academic entities. Session leaders represented numerous branches of the FDA and NIH Institutes and Centers, non-profit entities including the Human Variome Project and the European Federation for Medical Informatics, and research institutions including Stanford, the New York Genome Center, and the George Washington University.

It was decided that the BioCompute paradigm would be in the form of digital 'lab notebooks' which allow for the reproducibility, replication, review, and reuse, of bioinformatics protocols. This was proposed to enable greater continuity within a research group over the course of normal personnel flux while furthering the exchange of ideas between groups. The US FDA funded this work so that information on pipelines would be more transparent and accessible to their regulatory staff.[66]

In 2016, the group reconvened at the NIH in Bethesda and discussed the potential for a BioCompute Object, an instance of the BioCompute paradigm. This work was copied as both a "standard trial use" document and a preprint paper uploaded to bioRxiv. The BioCompute object allows for the JSON-ized record to be shared among employees, collaborators, and regulators.[67][68]

Education platforms

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While bioinformatics is taught as an in-person master's degree at many universities, there are many other methods and technologies available to learn and obtain certification in the subject. The computational nature of bioinformatics lends it to computer-aided and online learning.[69][70] Software platforms designed to teach bioinformatics concepts and methods include Rosalind and online courses offered through the Swiss Institute of Bioinformatics Training Portal. The Canadian Bioinformatics Workshops provides videos and slides from training workshops on their website under a Creative Commons license. The 4273π project or 4273pi project[71] also offers open source educational materials for free. The course runs on low cost Raspberry Pi computers and has been used to teach adults and school pupils.[72][73] 4273 is actively developed by a consortium of academics and research staff who have run research level bioinformatics using Raspberry Pi computers and the 4273π operating system.[74][75]

MOOC platforms also provide online certifications in bioinformatics and related disciplines, including Coursera's Bioinformatics Specialization at the University of California, San Diego, Genomic Data Science Specialization at Johns Hopkins University, and EdX's Data Analysis for Life Sciences XSeries at Harvard University.

Conferences

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There are several large conferences that are concerned with bioinformatics. Some of the most notable examples are Intelligent Systems for Molecular Biology (ISMB), European Conference on Computational Biology (ECCB), and Research in Computational Molecular Biology (RECOMB).

See also

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References

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Further reading

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[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia
Bioinformatics is an interdisciplinary subdiscipline of and that applies computational methods and tools to acquire, store, analyze, and disseminate , such as and sequences, thereby facilitating a deeper understanding of biological processes, , and . It integrates elements of , , and to manage and interpret vast, complex datasets generated by high-throughput experimental techniques, particularly in , , and other fields. This field addresses the challenges of the in biology, where advances in sequencing technologies have exponentially increased data volume, shifting emphasis from to meaningful interpretation and practical application in medical and contexts. The foundations of bioinformatics were established in the early 1960s through the application of computational approaches to protein , including de novo , the creation of biological sequence databases, and the development of substitution models for evolutionary studies. During the 1970s and 1980s, parallel advancements in —such as DNA manipulation and sequencing techniques—and in , including miniaturized hardware and sophisticated software, enabled the analysis of sequences and expanded the field's scope. The discipline experienced rapid growth in the 1990s and 2000s, driven by dramatic improvements in sequencing technologies and cost reductions, which generated massive "" volumes and necessitated robust methods for , storage, and management; this era was marked by the , which underscored bioinformatics' critical role in large-scale genomic endeavors. Bioinformatics plays a pivotal role in numerous applications across the life sciences, including , finding, and evolutionary tree construction, which are fundamental to understanding and . In drug discovery and development, it supports of chemical libraries, prediction of drug-target interactions, and assessment of compound toxicity through quantitative structure-activity relationship (QSAR) models, accelerating the identification of novel therapeutics against s like infections and cancer. Furthermore, the field advances precision medicine by analyzing genomic variants linked to conditions such as and mitochondrial disorders, integrating multi-omics data for diagnosis with high accuracy (e.g., up to 99% for certain classifications), and enabling personalized treatment strategies. Emerging integrations with and large language models continue to enhance its capabilities in areas like and systems-level cellular modeling.

Overview

Definition and Scope

Bioinformatics is an interdisciplinary field that applies computational tools and methods to acquire, store, analyze, and interpret , with a particular emphasis on large-scale datasets generated from high-throughput experiments such as and protein profiling. This approach integrates principles from , , , and to manage the complexity and volume of biological information. The scope of bioinformatics extends to the study of molecular sequences like DNA and RNA, protein structures and functions, cellular pathways, and broader biological systems. It encompasses subfields such as genomics, which investigates the structure, function, and evolution of genomes; proteomics, which focuses on the large-scale study of proteins including their interactions and modifications; and metabolomics, which profiles the complete set of small-molecule metabolites within cells or organisms to understand metabolic processes. The term "bioinformatics" was coined in 1970 by Dutch theoretical biologists Paulien Hogeweg and Ben Hesper, who used it to describe the study of informatic processes—such as storage, retrieval, and —in biotic systems. Although the fields overlap, bioinformatics is distinct from in its primary focus on developing and applying software tools, databases, and algorithms for biological data management and analysis, whereas emphasizes theoretical modeling and simulation of biological phenomena.

Importance and Interdisciplinary Nature

Bioinformatics plays a pivotal role in advancing biological research by accelerating through high-throughput analysis of genomic and proteomic data, enabling the identification of novel drug targets and existing compounds. It facilitates by integrating multi-omics data to tailor treatments based on individual genetic profiles, improving therapeutic outcomes and reducing adverse effects. Additionally, bioinformatics supports genomic surveillance efforts, such as real-time tracking of variants during the , which informed public health responses through phylogenetic analysis and variant detection. The interdisciplinary nature of bioinformatics bridges with , where algorithms process vast datasets; , for robust data modeling and inference; and , particularly in developing hardware solutions for handling volumes. This fusion enables the analysis of complex biological systems, from molecular interactions to population-level , fostering innovations across , , and . Economically, the bioinformatics market is projected to reach approximately US$20.34 billion in 2025, with growth propelled by the integration of for and for scalable and processing. However, key challenges persist, including data privacy concerns in genomic databases that risk unauthorized access to sensitive personal information, the lack of in data formats and interfaces that hinders , and ethical dilemmas in handling genomic data, such as and equitable access.

History

Origins in Molecular Biology

The discovery of the DNA double helix structure by James D. Watson and Francis H. C. Crick in 1953 revolutionized molecular biology by revealing the molecular basis of genetic inheritance and information storage. This breakthrough, built on X-ray crystallography data from Rosalind Franklin and Maurice Wilkins, underscored the need to understand nucleic acid sequences and their relations to protein structures. In parallel, during the 1950s, Frederick Sanger sequenced the amino acid chain of insulin, achieving the first complete determination of a protein's primary structure and earning the Nobel Prize in Chemistry in 1958 for developing protein sequencing techniques. These advances in molecular biology generated growing volumes of sequence data, highlighting the limitations of manual analysis. The integration of biophysics played a crucial role in the 1950s and 1960s, as enabled the determination of three-dimensional protein structures, such as in 1959 and in 1960, bridging sequence information with functional insights. Techniques like those refined by and provided atomic-level resolution, fostering interdisciplinary approaches that anticipated computational needs for handling structural and sequential data. By the mid-1960s, the influx of protein sequences from methods like overwhelmed manual comparison efforts, prompting the development of early algorithms. This shift toward computation culminated in the 1970 publication of the Needleman-Wunsch algorithm by Saul B. Needleman and Christian D. Wunsch, which introduced dynamic programming for optimal global alignment of protein sequences, addressing the need for systematic similarity detection. Institutional foundations emerged in the late 1960s, with Margaret Oakley Dayhoff at the National Biomedical Research Foundation (supported by the NIH) compiling the first protein sequence database, the Atlas of Protein Sequence and Structure in 1965, which included 65 entries and tools for analysis. In Europe, collaborative efforts through the European Molecular Biology Organization (EMBO), founded in 1964, began coordinating molecular biology resources, paving the way for bioinformatics initiatives at the (EMBL) established in 1974.

Key Milestones and Developments

The 1980s marked the foundational era for bioinformatics databases and sequence comparison tools. In 1982, the National Institutes of Health (NIH) established GenBank at Los Alamos National Laboratory as the first publicly accessible genetic sequence database, enabling researchers to submit and retrieve DNA sequence data from diverse organisms. This initiative, funded by the U.S. Department of Energy and NIH, rapidly grew to include annotated sequences, laying the groundwork for collaborative genomic data sharing. By 1985, the FASTA algorithm, developed by David J. Lipman and William R. Pearson, introduced a heuristic approach for rapid and sensitive protein similarity searches, significantly improving efficiency over exhaustive methods by identifying diagonal matches in dot plots and extending them into alignments. The 1990s saw bioinformatics propelled by large-scale international projects and algorithmic innovations. Launched in October 1990 by the U.S. Department of Energy and NIH, the (HGP) aimed to sequence the entire , fostering advancements in sequencing automation, data management, and computational analysis that accelerated the field's growth. The project culminated in April 2003 with a draft sequence covering approximately 99% of the euchromatic at an accuracy of over 99.99%, generating vast datasets that spurred bioinformatics tool development. Concurrently, in 1990, F. Altschul and colleagues introduced the Basic Local Alignment Search Tool (BLAST), a faster alternative to FASTA that uses word-based indexing to approximate local alignments, becoming indispensable for querying sequence databases like . Entering the , technological breakthroughs expanded bioinformatics to high-throughput . The (Encyclopedia of DNA Elements) project, initiated by the (NHGRI) in 2003, sought to identify all functional elements in the through integrated experimental and computational approaches, producing comprehensive maps of regulatory regions and influencing subsequent genomic annotation efforts. In 2005, 454 Life Sciences (later acquired by ) commercialized the first next-generation sequencing (NGS) platform using in picoliter reactors, enabling parallel sequencing of millions of short DNA fragments and reducing sequencing costs from millions to thousands of dollars. The 2010s and early 2020s integrated advanced sequencing with gene editing and predictive modeling. Single-cell RNA sequencing (scRNA-seq), pioneered in 2009 and widely adopted in the 2010s, allowed transcriptomic profiling of individual cells, revealing cellular heterogeneity and developmental trajectories through computational pipelines for and clustering. Following the 2012 demonstration of CRISPR-Cas9 as a programmable DNA endonuclease, bioinformatics tools emerged to design guide RNAs, predict off-target effects, and analyze editing outcomes, such as CRISPR Design Tool and Cas-OFFinder, facilitating precise genome engineering applications. In 2020, DeepMind's achieved breakthrough accuracy in during the CASP14 competition, using on multiple sequence alignments and structural templates to model atomic-level folds for previously unsolved proteins. Recent developments from 2024 to 2025 have emphasized AI integration across layers. Multi- platforms advanced with unified frameworks, such as those combining , transcriptomics, and via , enabling holistic analysis of disease mechanisms as seen in tools like MOFA+ for . In AI-driven , models like 3, released by DeepMind in 2024, extended predictions to biomolecular complexes including ligands and nucleic acids, accelerating and lead optimization with diffusion-based architectures that improved accuracy for protein-small molecule interactions by up to 50% over prior methods. These innovations have shortened timelines, with AI platforms identifying novel targets and predicting efficacy in clinical contexts.

Core Concepts

Types of Biological Data

Biological data in bioinformatics primarily consists of diverse formats derived from experimental observations of molecular and cellular phenomena, serving as the raw material for computational analysis. These data types range from simple textual representations of genetic sequences to complex, multidimensional profiles generated by high-throughput technologies. Key categories include sequence data, structural data, functional data, and datasets, each requiring specialized storage and handling to support biological inquiry. Sequence data forms the cornerstone of bioinformatics, representing linear strings of nucleotides in DNA or RNA and amino acids in proteins. These sequences are typically encoded as text in formats such as , which pairs a descriptive header with the raw sequence string, facilitating storage and retrieval for evolutionary and functional studies. Mutations within these sequences are commonly denoted as single nucleotide polymorphisms (SNPs), which indicate variations at specific positions and are crucial for understanding . Sequence data also includes quality scores in formats like FASTQ, where Phred scores quantify base-calling reliability to account for sequencing errors. Structural data captures the three-dimensional architecture of biomolecules, essential for elucidating their physical interactions and functions. This data is often stored in (PDB) files, which detail atomic coordinates, bond lengths, and angles derived from experimental methods. Outputs from cryo-electron microscopy (cryo-EM) provide electron density maps at near-atomic resolution, while nuclear magnetic resonance (NMR) spectroscopy yields ensembles of conformational models. These formats enable visualization and simulation of but demand precise geometric representations to avoid distortions in downstream modeling. Functional data quantifies biological activity and interactions, bridging sequence and structure to reveal mechanistic insights. Gene expression data, for instance, consists of numerical values representing mRNA or protein abundance levels, often derived from microarrays as intensity matrices or from RNA sequencing as read counts per gene. Interaction data is depicted as matrices or graphs, outlining pairwise associations such as protein-protein binding affinities or gene regulatory relationships. These datasets highlight dynamic processes like cellular responses but are prone to noise from experimental variability. Omics data encompasses high-dimensional profiles from systematic surveys of biological systems, including , , and . Genomic data includes complete DNA sequences, spanning billions of base pairs per organism, while proteomic data features mass spectrometry spectra identifying thousands of peptides and their post-translational modifications. Metabolomic profiles catalog small-molecule concentrations via chromatographic or spectroscopic readouts, reflecting metabolic states. These datasets integrate multiple layers to model holistic biological networks. The proliferation of omics technologies has amplified challenges in bioinformatics, characterized by immense , variety, and . Next-generation sequencing alone generates petabytes of annually, necessitating scalable storage solutions. variety spans structured formats like sequences alongside unstructured elements such as images, complicating integration across modalities. arises from streams in clinical or , demanding rapid processing to maintain analytical relevance. Heterogeneity further exacerbates issues, as inconsistencies in calibration and —often Poisson-distributed in expression —require robust preprocessing for accuracy.

Fundamental Computational Techniques

Fundamental computational techniques in bioinformatics encompass a set of core algorithms, statistical methods, data structures, and programming approaches that enable the analysis and interpretation of . These techniques form the foundational toolkit for processing sequences, inferring relationships, and modeling biological processes, often drawing from and to handle the complexity and scale of genomic information. Dynamic programming, for instance, provides an efficient means to solve optimization problems in sequence comparison, while statistical frameworks ensure robust inference amid noise and variability in experimental data. Data structures like trees and graphs facilitate representation of evolutionary and interaction networks, and programming paradigms in languages such as Python and support implementation and scalability through parallelization. A cornerstone algorithm in bioinformatics is dynamic programming, particularly for pairwise sequence alignment, which identifies regions of similarity between biological sequences to infer functional or evolutionary relationships. The Needleman-Wunsch algorithm, introduced in 1970, employs dynamic programming to compute optimal global alignments by filling a scoring matrix iteratively, maximizing the similarity score across entire sequences. For local alignments, the Smith-Waterman algorithm, developed in 1981, modifies this approach to focus on the highest-scoring subsequences, making it suitable for detecting conserved domains without penalizing terminal mismatches. These methods rely on substitution matrices to quantify the likelihood of or replacements; the Point Accepted Mutation (PAM) matrices, derived from closely related protein alignments, model evolutionary distances for global alignments, while the BLOcks SUbstitution Matrix (), constructed from conserved blocks in distantly related proteins, is optimized for local alignments and remains widely used due to its empirical basis. The scoring function in these alignments is defined as S=s(xi,yj)+g(k)S = \sum s(x_i, y_j) + \sum g(k), where s(xi,yj)s(x_i, y_j) is the substitution score from the matrix for aligned residues xix_i and yjy_j, and g(k)g(k) is the for insertions or deletions of length kk. To account for the biological reality that opening a gap is more costly than extending it, affine gap penalties are commonly applied: g(k)=de(k1)g(k) = -d - e(k-1), with dd as the opening penalty and ee as the extension penalty; this formulation, proposed by Gotoh in , reduces from cubic to quadratic time while improving alignment accuracy for indels. Such scoring ensures that alignments reflect plausible evolutionary events rather than artifacts. Statistical methods underpin the reliability of bioinformatics analyses by quantifying uncertainty and controlling error rates in testing. In , p-values assess the significance of observed similarities against null models of random chance, often derived from extreme value distributions for alignment scores. Multiple testing arises frequently due to the high dimensionality of genomic data, necessitating corrections like the Bonferroni method, which adjusts the significance threshold by dividing by the number of tests (e.g., α/m\alpha / m for mm hypotheses) to maintain the at a desired level. complements frequentist approaches by incorporating prior knowledge into posterior probability estimates, enabling probabilistic modeling of sequence motifs or evolutionary parameters through techniques like . Data structures are essential for efficiently storing and querying biological information. Phylogenetic trees, typically represented as rooted or unrooted hierarchical structures, model evolutionary relationships among species or sequences, with nodes denoting ancestors and branches indicating divergence times or genetic distances; these are constructed using distance-based or character-based methods and are pivotal for reconstructing ancestry. Graphs, often directed or undirected, capture interaction networks such as protein-protein associations or metabolic pathways, where nodes represent biomolecules and edges denote relationships, allowing analysis of connectivity and modularity. Hashing techniques accelerate sequence searches by indexing k-mers into tables for rapid lookups, as exemplified in early database scanning tools that preprocess queries to avoid exhaustive comparisons. Programming paradigms in bioinformatics leverage domain-specific libraries to implement these techniques scalably. Python, with the suite, provides tools for parsing sequences, performing alignments, and interfacing with databases, facilitating rapid prototyping and integration with workflows. , augmented by the project, excels in statistical analysis of high-throughput data, offering packages for differential expression and visualization through its extensible object-oriented framework. basics, such as distributing alignment tasks across multiple processors using message-passing interfaces, address the computational demands of large datasets, enabling faster processing on clusters without altering algorithmic logic.

Sequence Analysis

Sequencing Technologies

Sequencing technologies form the cornerstone of bioinformatics by generating vast amounts of data essential for downstream computational analyses. These methods have evolved from labor-intensive, low-throughput approaches to high-speed, platforms that enable the study of genomes, transcriptomes, and epigenomes at unprecedented scales. The progression reflects advances in biochemistry, , and data handling, dramatically reducing costs and increasing accessibility for biological research. The foundational technique, , introduced in 1977, relies on the chain-termination method using dideoxynucleotides to halt at specific bases, producing fragments that are separated by to read the sequence. Developed by and colleagues, this method achieved high accuracy, exceeding 99.9% per base, making it the gold standard for validating sequences and small-scale projects despite its low throughput, typically limited to 500-1000 bases per reaction. Next-generation sequencing (NGS) marked a in the mid-2000s, enabling massively parallel processing of millions of DNA fragments simultaneously for higher throughput and lower cost per base. Illumina's platform, originating from Solexa technology, launched the Genome Analyzer in 2006, producing short reads of 50-300 base pairs and generating up to 1 gigabase of data per run through sequencing-by-synthesis with reversible terminators. In parallel, (PacBio) introduced single-molecule real-time (SMRT) sequencing in the , specializing in long reads exceeding 10 kilobases by observing continuous activity with fluorescently labeled , which facilitates resolving complex genomic regions though at higher initial error rates compared to short-read methods. Third-generation sequencing technologies further advanced the field by focusing on single-molecule, real-time analysis without amplification, allowing for longer reads and portability. released the MinION device in 2014, a USB-powered sequencer that measures ionic current changes as DNA passes through a protein , enabling real-time, portable sequencing with reads up to hundreds of kilobases. Early MinION runs exhibited raw error rates around 38%, primarily due to homopolymer inaccuracies, but subsequent improvements in basecalling algorithms and pore engineering have reduced these to under 5% for consensus sequences, often aided by hybrid approaches combining data with short-read corrections. By 2024-2025, sequencing innovations emphasized ultra-long reads for phasing and structural variant detection, alongside aggressive cost reductions driven by scalable platforms like Illumina's NovaSeq X series. These ultra-long reads, achievable with optimized protocols, exceed 100 kilobases routinely, enhancing de novo assembly completeness in repetitive genomes. Whole-genome sequencing costs have approached or fallen below $100 per sample in high-throughput settings, fueled by increased flow cell capacities and AI-optimized chemistry, democratizing access for population-scale studies. Sequencing outputs are standardized in FASTQ files, which interleave nucleotide sequences with corresponding quality scores to indicate base-calling reliability. Quality scores follow the Phred scale, defined as Q=10log10(P)Q = -10 \log_{10}(P), where PP is the estimated error probability for a base; for instance, Q30 corresponds to a 0.1% error rate, ensuring robust filtering in bioinformatics pipelines.

Alignment and Assembly Methods

Pairwise sequence alignment is a foundational technique in bioinformatics for identifying similarities between two biological sequences, such as DNA, RNA, or proteins, by optimizing an alignment score that accounts for matches, mismatches, and gaps. Global alignment, which aligns the entire length of two sequences, was introduced by Needleman and Wunsch in 1970 using dynamic programming to maximize the score across the full sequences. This method constructs a scoring matrix where each cell represents the optimal alignment score for prefixes of the sequences, enabling the traceback to recover the alignment path. In contrast, local alignment focuses on the highest-scoring subsequences, which is particularly useful for detecting conserved regions within larger, unrelated sequences; it was developed by Smith and Waterman in 1981, modifying the dynamic programming approach to allow scores to reset to zero when negative. The core of these dynamic programming algorithms is the recurrence relation for the scoring matrix D[i,j]D[i,j], which computes the maximum score for aligning the first ii characters of sequence AA with the first jj characters of sequence BB: D[i,j]=max{D[i1,j1]+s(ai,bj)D[i1,j]δD[i,j1]δD[i,j] = \max \begin{cases} D[i-1,j-1] + s(a_i, b_j) \\ D[i-1,j] - \delta \\ D[i,j-1] - \delta \end{cases}
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