The humerus and the femur are corresponding bones of the arms and legs, respectively. While their parts are similar in general, their structure has been adapted to differing functions. The head of the humerus is almost hemispherical, while that of the femur forms about two-thirds of a sphere.
The radius is on the lateral side of the arm, while the ulna is medial. The radius can turn at the elbow joint, and therefore the part of the radius that articulates with the humerus, called the radial head, has a rounded circumference that allows it to rotate in contact with the proximal ulna.
Phytochrome is a blue protein pigment responsible for the perception of light in photo-physiological processes. It is possibly the only photoreceptor in photoperiodism and the flowering process.
The discovery of phytochrome is closely associated with studies on flowering. However, many other light controlled plant responses other than photosynthesis, collectively called photo-morphogenesis, are the effects of phytochrome action.
Cryptochromes are a class of flavoproteins that are sensitive to blue light. They are found in plants and animals. Cryptochromes are involved in the circadian rhythms of plants and animals, and possibly also in the sensing of magnetic fields in a number of species.
Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation catalyzed by protein kinases, which ultimately results in a cellular response. Proteins responsible for detecting stimuli are generally termed receptors, although in some cases the term sensor is used.The changes elici... moreted by ligand binding (or signal sensing) in a receptor give rise to a signaling cascade, which is a chain of biochemical events along a signaling pathway. When signaling pathways interact with one another they form networks, which allow cellular responses to be coordinated, often by combinatorial signaling events. At the molecular level, such responses include changes in the transcription or translation of genes, and post-translational and conformational changes in proteins, as well as changes in their location. These molecular events are the basic mechanisms controlling cell growth, proliferation, metabolism and many other processes. In multicellular organisms, signal transduction pathways have evolved to regulate cell communication in a wide variety of ways.
Osmosis is the special type of diffusion in which the movement of solute particles from region of low concentration to the region of high concentration through a semi permeable membrane until a dynamic state of equilibrium obtained