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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.
Some of the earliest ideas and mathematical descriptions on how physical processes and constraints affect biological growth, and hence natural patterns such as the spirals of phyllotaxis, were written by D'Arcy Wentworth Thompson in his 1917 book On Growth and Form [2] [3] [note 1] and Alan Turing in his The Chemical Basis of Morphogenesis (1952). [6]
Morphogenesis of Drosophila fruit flies is intensively studied in the laboratory. A morphogen is a substance whose non-uniform distribution governs the pattern of tissue development in the process of morphogenesis or pattern formation, one of the core processes of developmental biology, establishing positions of the various specialized cell types within a tissue.
An example is thermo-regulation in Sauropsida, which is the clade containing the lizards, turtles, crocodiles, and birds. Lizards, turtles, and crocodiles are ectothermic (coldblooded), while birds are endothermic (warmblooded). Being coldblooded is symplesiomorphic for lizards, turtles, and crocodiles, but they do not form a clade, as ...
The pygmy mammoth is an example of insular dwarfism, a case of Foster's rule, its unusually small body size an adaptation to the limited resources of its island home. A biological rule or biological law is a generalized law , principle , or rule of thumb formulated to describe patterns observed in living organisms.
Biological processes are regulated by many means; examples include the control of gene expression, protein modification or interaction with a protein or substrate molecule. Homeostasis: regulation of the internal environment to maintain a constant state; for example, sweating to reduce temperature
Failure to maintain control over pre-RC formation at replication origins results in a phenomenon known as "rereplication" which is common in cancer cells. [2] The mechanism by which cyclin E-Cdk2 inhibits pre-RC formation involves downregulation of APC - Cdh1 -mediated proteolysis and accumulation of the protein Geminin , which is responsible ...
A classic example of an equivalence group is the vulva precursor cells (VPCs) of nematodes. In Caenorhabditis elegans self-fertilized eggs exit the body through the vulva . This organ develops from a subset of cell of an equivalence group consisting of six VPCs, P3.p-P8.p, which lie ventrally along the anterior-posterior axis. [ 5 ]