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A sample UML class and sequence diagram for the Flyweight design pattern. [6] The above UML class diagram shows: the Client class, which uses the flyweight pattern; the FlyweightFactory class, which creates and shares Flyweight objects; the Flyweight interface, which takes in extrinsic state and performs an operation
A simplification of an allopatric speciation experiment where two lines of fruit flies are raised on maltose and starch media. Laboratory experiments of speciation have been conducted for all four modes of speciation: allopatric, peripatric, parapatric, and sympatric; and various other processes involving speciation: hybridization, reinforcement, founder effects, among others.
The theory, which can be called a reaction–diffusion theory of morphogenesis, has become a basic model in theoretical biology. [2] Such patterns have come to be known as Turing patterns. For example, it has been postulated that the protein VEGFC can form Turing patterns to govern the formation of lymphatic vessels in the zebrafish embryo. [3]
Three examples of Turing patterns Six stable states from Turing equations, the last one forms Turing patterns. The Turing pattern is a concept introduced by English mathematician Alan Turing in a 1952 paper titled "The Chemical Basis of Morphogenesis" which describes how patterns in nature, such as stripes and spots, can arise naturally and autonomously from a homogeneous, uniform state.
In developmental biology, pattern formation refers to the generation of complex organizations of cell fates in space and time. The role of genes in pattern formation is an aspect of morphogenesis , the creation of diverse anatomies from similar genes, now being explored in the science of evolutionary developmental biology or evo-devo.
Stentor coeruleus, used in molecular biology (its genome has been sequenced), [5] and is studied as a model of single-cell regeneration.; Dictyostelium discoideum, used in molecular biology and genetics (its genome has been sequenced), and is studied as an example of cell communication, differentiation, and programmed cell death.
Drosophila embryogenesis, the process by which Drosophila (fruit fly) embryos form, is a favorite model system for genetics and developmental biology. The study of its embryogenesis unlocked the century-long puzzle of how development was controlled, creating the field of evolutionary developmental biology. [1]
In the French flag model, the French flag is used to represent the effect of a morphogen on cell differentiation: a morphogen affects cell states based on concentration, these states are represented by the different colors of the French flag: high concentrations activate a "blue" gene, lower concentrations activate a "white" gene, with "red" serving as the default state in cells below the ...