This list of research methods in biology is an index to articles about research methodologies used in various branches of biology.
Research design and analysis Research designs Research design Utility Potential analysis Between-group design Experiment that has two or more groups of subjects each being tested by a different testing factor simultaneously Student's t-test, Analysis of variance, Mann–Whitney U test Repeated measures design A research design that involves multiple measures of the same variable taken on the same or matched subjects either under different conditions or over two or more time periods. Paired t-test, Wilcoxon signed-rank test
Charts and diagrams Analysis Utility Branch Dose–response curves Graph that shows the magnitude of the response of an organism, as a function of exposure (or doses) to a stimulus or stressor (usually a chemical) after a certain exposure time Physiology Electroencephalogram Graph that shows voltage fluctuations resulting from ionic current within the neurons of the brain Neuroscience Electrocardiogram Graph of voltage versus time of the electrical activity of the heart using electrodes placed on the skin PhysiologyIdentification keyUsed to identify a specimen organism from a set of known taxa.Systematics, Taxonomy Manhattan plot Used to display data with a large number of data-points, many of non-zero amplitude, and with a distribution of higher-magnitude values. The plot is commonly used in genome-wide association studies (GWAS) to display significant SNPs. Genetics Pedigree chart Used to show the occurrence of phenotypes of a particular gene or organism and its ancestors from one generation to the next,pedigree chart Genealogy Glossary - About.com, a part of The New York Times Company.Documenting Your Pedigree Chart By Melody Daisson - GeneaSearch.com most commonly humans, show dogs, and race horses Genetics Phylogenetic tree Used to show the evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical or genetic characteristics Systematics, Evolutionary biology Population pyramid Used to illustrate the distribution of a population (typically that of a country or region of the world) by age groups and sex; it typically forms the shape of a pyramid when the population is growing Population ecology Punnett square Used to predict the genotypes of a particular cross or breeding experiment Genetics
Statistical analyses Analysis Utility Type Analysis of variance A collection of statistical models and their associated estimation procedures (such as the "variation" among and between groups) used to analyze the differences among means Statistical model Chi-squared test A statistical hypothesis test that is valid to perform when the test statistic is chi-squared distributed under the null hypothesis, specifically Pearson's chi-squared test and variants thereof Statistical hypothesis test Mann–Whitney U test A statistical hypothesis test of the null hypothesis that, for randomly selected values X and Y from two populations, the probability of X being greater than Y is equal to the probability of Y being greater than X Nonparametric statistics Student's t-test Any statistical hypothesis test in which the test statistic follows a Student's t-distribution under the null hypothesis Parametric statistics
Laboratory techniques Method Utility Branches Agarose gel electrophoresis Used to separate a mixed population of macromolecules such as DNA or proteins in a matrix of agarose, one of the two main components of agar Biochemistry, Molecular biology, Genetics Animal Model Used for researching diseases and disorders in humans. Some animals may have human-like traits, such as mice, while others may have traits that are ideal for research, such as the squid giant axon Biochemistry, Neuroscience, Physiology Biological ablation Used to remove a biological structure or functionality Genetics, Physiology Calcium imaging Used to optically measure the status of calcium ions (Ca2+) in an isolated cell, tissue or medium Physiology Cell isolation Process of separating individual living cells from a solid block of tissue or cell suspension Cell biology Centrifugation Use of centrifugal force to separate particles from a solution according to their size, shape, density, medium viscosity, and rotor speed Cell biology, Biochemistry CRISPR gene editing Used to modify the genomes of living organisms based on a simplified version of the bacterial CRISPR-Cas9 antiviral defense system Molecular biology DNA sequencer Used to automate the DNA sequencing process Genetics, Molecular biology Enzyme-linked immunosorbent assay (ELISA) Used to detect the presence of a ligand (commonly a protein) in a liquid sample using antibodies directed against the protein to be measure Biochemistry, Molecular biology Gene knockout Used to make one of an organism's genes inoperative ("knocked out" of the organism) Molecular biology, Genetics Immunostaining Used of an antibody-based method to detect a specific protein in a sample Molecular biology, Biochemistry Intracellular recording Used to measure the voltage across a cell membrane Neuroscience, Electrophysiology Microarray Assays (tests) large amounts of biological material using high-throughput screening miniaturized, multiplexed and parallel processing and detection methods Genetics, Molecular biology Microelectrode array Devices that contain multiple (tens to thousands) microelectrodes through which neural signals are obtained or delivered, essentially serving as neural interfaces that connect neurons to electronic circuitry Neuroscience Microscope Used to examine objects that are too small to be seen by the naked eye Cell biology Molecular cloning Used to assemble recombinant DNA molecules and to direct their replication within host organisms. Molecular biology Northern blot Used to study gene expression by detection of RNA (or isolated mRNA) in a sample.Alberts, B., Johnson, A., Lewis, J. Raff, M., Roberts, K., Walter, P. 2008. Molecular Biology of the Cell, 5th ed. Garland Science, Taylor & Francis Group, NY, pp 538–539.Kevil, C. G., Walsh, L., Laroux, F. S., Kalogeris, T., Grisham, M. B., Alexander, J. S. (1997) An Improved, Rapid Northern Protocol. Biochem. and Biophys. Research Comm. 238:277–279. Molecular biology Optogenetics Uses light to control neurons that have been genetically modified to express light-sensitive ion channels Neuroscience Oscilloscope Used to graphically displays varying signal voltages, usually as a calibrated two-dimensional plot of one or more signals as a function of time Neuroscience, Physiology Paper chromatography Used to separate coloured chemicals or substances. Molecular biology Patch clamp Used to study ionic currents in individual isolated living cells, tissue sections, or patches of cell membrane Electrophysiology, Neuroscience Polymerase chain reaction (PCR) Used to rapidly make millions to billions of copies (complete copies or partial copies) of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it (or a part of it) to a large enough amount to study in detail Genetics, Molecular biology Somatic cell nuclear transfer Used for creating a viable embryo from a body cell and an egg cell Developmental biology Southern blot Used to detect specific DNA sequence in DNA samples Molecular biology Test cross Used to determine whether an individual is homozygous or heterozygous dominant Genetics Voltage clamp Used to measure the ion currents through the membranes of excitable cells, such as neurons, while holding the membrane voltage at a set level. Physiology, Neuroscience Western blot Used analytical technique in molecular biology and immunogenetics to detect specific proteins in a sample of tissue homogenate or extract Molecular biology X-ray crystallography Used to determine the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions Structural biology
Field techniques Method Utility Branches Distance sampling Used for estimating the density and/or abundance of populations Ecology Mark and recapture Used to estimate an animal population's size where it is impractical to count every individual. Ecology
Computational tools Mathematical models Model Utility Branches Exponential integrate-and-fire Describes compact and computationally efficient nonlinear spiking neuron models with one or two variables Neuroscience FitzHugh–Nagumo model Describes a prototype of an excitable system (e.g., a neuron) Neuroscience Hardy–Weinberg principle States that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences Genetics, Evolutionary biology Hodgkin–Huxley model Describes how action potentials in neurons are initiated and propagated Neuroscience Infinite sites model Allows for the calculation of heterozygosity, or genetic diversity, in a finite population and for the estimation of genetic distances between populations of interest Evolutionary biology Logistic growth Describes the growth of a population as exponential, followed by a decrease in growth, and bound by a carrying capacity due to environmental pressures. Ecology Lotka–Volterra equations Describe the dynamics of biological systems in which two species interact, one as a predator and the other as prey Ecology Moran process Stochastic process that describes finite populations Genetics Species–area relationship describes the relationship between the area of a habitat, or of part of a habitat, and the number of species found within that area Ecology
Algorithms Algorithm Utility Branches Evolutionary algorithm Uses mechanisms inspired by biological evolution. Candidate solutions to the optimization problem play the role of individuals in a population, and the fitness function determines the quality of the solutions. Neuroscience
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