Definition of tropism - What it is, Meaning and Concept

The notion of tropism is used in the biology to name the displacement performed by the plants or certain Organs of them to respond to a stimulus that arrives from the outside.

There are different kinds of tropisms according to the nature of the stimulus.When the reaction of the plant is caused by the force of gravity and its acceleration, there is talk of gravitropism .The roots, in this case, grow towards the ground while the stems are develop upwards until it comes to the surface.The root tropism is said to be positive (accompanying the force of gravity), while the tropism of the stems is negative (opposite to the mentioned force).

Due to the phototropism , the plants react to the light , which allows the development of the photosynthesis .Unlike what happens with gravitropism, in this case the roots exhibit a negative phototropism and the stems have a positive phototropism.Within the phototropisms, the heliotropism stands out : the tropism that implies a movement of the plant according to the orientation of the sun .

Other kinds of tropisms are those recognized as part of the chemotropisms , which are linked to plant responses to chemical elements.When these elements are beneficial to the plant organism, the plant organism can occur. aerotropism (the stems are oriented to the aerated regions of the surface) or the hydrotropism (they are directed to the water).

By contacting a solid , finally, plants can develop thigmotropism , a reaction that causes a change in their growth.This type of tropism is the made by climbing vegetables.

Tropic tropism

In virology, the branch of microbiology that studies the virus , we talk about tissue tropism to refer to the affinity that a given virus has with one or more tissues of its host (also called a host).Some of the factors that influence its distribution are the following: how susceptible the host is; that there are recipients of the virus in question in the host organism; the virus reproduction rate (this cycle is also known as viral replication ).

Tissue tropism can also occur or increase due to the presence of soluble proteins or cytokines (also known as cytokines , are proteins that are responsible for regulating the functioning of certain cells and their communication, among other tasks) that counteract the action of the host.The phenomenon may also favor the development of bacteria, and that the affinity can be to a particular tissue or to a large number of different tissues and cells.

A clear example of tissue tropism occurs in porcine adenovirus type 3, which is similar to columnar epithelial cells.Similarly, bovine adenovirus is attracted to capillary endothelial cells.rage, on the other hand, presents an almost exclusive affinity to the neuronal tissue .

Proteins found in cells are known as cellular receptors and they have the power to allow fusion with a virus cell.Through the process of tissue tropism, the way these proteins acquire is comparable to the one they show during an infection.

Some of the stages that are identified throughout tissue tropism are the following:

* the virus enters the organism ; * its cells merge with others; * takes place a process known as reverse transcription , which consists in generating double stranded DNA from a single stranded RNA; * the virus particles sprout and acquire the tissue needed to continue tropism.