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In contrast, a signal can act in a gradient, which induces a specific cell fate as a function of the concentration of the molecule in the gradient. These types of molecules are known as morphogens. An example of this phenomenon is observed in the neural tube with varying concentrations of the Sonic Hedgehog protein. [1]
Ordination or gradient analysis, in multivariate analysis, is a method complementary to data clustering, and used mainly in exploratory data analysis (rather than in hypothesis testing). In contrast to cluster analysis, ordination orders quantities in a (usually lower-dimensional) latent space. In the ordination space, quantities that are near ...
An example of primary active transport using redox energy is the mitochondrial electron transport chain that uses the reduction energy of NADH to move protons across the inner mitochondrial membrane against their concentration gradient. An example of primary active transport using light energy are the proteins involved in photosynthesis that ...
In multivariate analysis, canonical correspondence analysis (CCA) is an ordination technique that determines axes from the response data as a unimodal combination of measured predictors. CCA is commonly used in ecology in order to extract gradients that drive the composition of ecological communities.
Typically, the ion(s) will move down the electrochemical gradient, allowing the other molecule(s) to move against the concentration gradient. The movement of the ion(s) across the membrane is facilitated diffusion, and is coupled with the active transport of the molecule(s). In symport, two molecule move in a 'similar direction' at the 'same time'.
One example of passive diffusion is the gas exchange that occurs between the oxygen in the blood and the carbon dioxide present in the lungs. [3] Facilitated diffusion is the movement of polar molecules down the concentration gradient with the assistance of membrane proteins. Since the molecules associated with facilitated diffusion are polar ...
For each sample along the gradient, a new species is introduced but another species is no longer present. The result is a sparse matrix. Ones indicate the presence of a species in a sample. Except at the edges each sample contains five species. Comparison of Correspondence Analysis and Detrended Correspondence Analysis on example (ideal) data.
A selection gradient describes the relationship between a character trait and a species' relative fitness. [1] A trait may be a physical characteristic, such as height or eye color, or behavioral, such as flying or vocalizing. Changes in a trait, such as the amount of seeds a plant produces or the length of a bird's beak, may improve or reduce ...