Knowledge Is Power

Signal transmission paths Introduction Once the signaling molecule (ligand) of one cell binds to the receptor of another, is the signaling process complete? If we are talking about intracellular receptors that bind their ligand inside the cell and directly activate genes, the answer could be yes. In most cases, however, the answer is no, not at all! In the case of receptors located on the cell membrane, the signal must be transmitted by other molecules within the cell, in a kind of "telephone" game. The chains of molecules that transmit signals within a cell are known as intracellular signal transduction pathways. Here we will see the general characteristics of intracellular signal transduction pathways, as well as some transmission mechanisms commonly used in these pathways. Binding initiates a signaling pathway When a ligand binds to a cell surface receptor, the receptor's intracellular domain (the region inside the cell) changes in some way. It usually takes on a new f

Spatiotemporal signal propagation in complex networks A major achievement in the study of complex networks is the realization that diverse systems, from sub-cellular biology to social networks, exhibit universal topological characteristics. Yet, such universality does not naturally translate to the dynamics of these systems, as dynamic behavior cannot be uniquely predicted from topology alone. Rather, it depends on the interplay of the network’s topology with the dynamic mechanisms of interaction between the nodes. Hence, systems with similar structure may exhibit profoundly different dynamic behavior. We therefore seek a general theoretical framework to help us systematically translate topological elements into their predicted dynamic outcome. Here, we offer such a translation in the context of signal propagation, linking the topology of a network to the observed spatiotemporal spread of perturbative signals across it, thus capturing the network’s role in propagating local information

 Filter (signal processing) In signal processing, a filter is a device or process that extracts some unwanted components or features from a signal. Filtering is a class of signal processing whose defining feature is the complete or partial suppression of some aspect of a signal. Most often it means certain frequencies or frequency ranges. However, filters do not operate in the frequency domain, especially in the field of image processing, there are many other purposes for filtering. Filters are widely used in electronics and telecommunications, radio, television, audio recording, radar, control systems, music synthesis, image processing, and computer graphics. There are many different bases for classifying filters, and these overlap in different ways; there is no simple hierarchical classification. Filters can be: non-linear or linear time variant or time invariant , also known as shift invariance. If the filter operates in the spatial domain, then the characteristic is spatial invaria

  Pheromones Pheromones are invisible chemical signals between members of the same species. This is probably the most common mode of communication in the animal kingdom. The discovery of pheromones We meet references to the existence of pheromones from very ancient times. The ancient Greeks were familiar with the invisible signals that dogs emit during estrus and that males feel. They knew that if the female's secretions were placed on a towel, the male would follow the towel. It's not the sound the females made, it's the smell. The problem is that the number of pheromones is very small, and most people are not able to smell such signals between animals. Only in the 1950s, after twenty years of work by a group of chemists led by Adolf Butenandt, who received the Nobel Prize for his work on human molecules - steroids, was a paper published with the chemical definition of the first pheromone. It was bombykol, the female sex pheromone of the silkworm.      How Pheromones Work

Classification of pheromones According to their effects, pheromones are divided into two main types: releasers and primers. Releasers  ( eng.  releaser ) encourage the individual to take some immediate action; are used to attract mates, signal danger, and prompt other immediate action. Primers ( eng.  primer ) are used to form certain behavior and influence the development of other individuals: for example, a special pheromone secreted by the queen bee and suppresses the sexual development of other female bees, thus turning them into worker bees. As separate names for some types of pheromones, the following can be given: epagons - sexual attractants ; odmihnions - path marks indicating the way to a hole or to found prey, marks on the boundaries of an individual territory; toribones - pheromones of fear and anxiety ; gonophyons - pheromones that induce sex change ; gamophions - pheromones of puberty; etofion - pheromones of behavior; Lichneumons are pheromones that disguise an animal as

  Brief table of contents  Cell Signaling Between separate organisms of the same species Classification In Multicellular Organisms In plants Cell To Cell Signaling in plants Paracrine signaling Synaptic signaling Synaptic signaling Autocrine signaling Endocrine signaling Signaling through cell-cell contact Signaling in plants occurs through plant hormone Signaling in plants occurs through Phytochrome Phytochrome Signaling Mechanisms PLANT PHYTOCHROMES Signaling Receptors The receptor-ligand interaction can be classified as: Overview of Signaling: Key components of the signal transduction pathway What is Signaling? Have you ever become separated from a friend while in a crowd?  You know the challenge of Finding someone when surrounded by hundreds of other people. If you and your friend have Mobile phones, your chances of finding each other are very good. A cell phone’s ability to send and receive messages makes it an ideal communication device. Cell Signaling In biology, cell signalin