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The aromatic/arginine or "ar/R" selectivity filter is a cluster of amino acids that help bind to water molecules and exclude other molecules that may try to enter the pore. It is the mechanism by which the aquaporin is able to selectively bind water molecules and so to allow them through, and to prevent other molecules from entering.
Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration of electrolytes (salts in solution which in this case is represented by body fluid) to keep the body fluids from becoming too diluted or concentrated.
The phrase "fight like cats and dogs" reflects a natural tendency for the relationship between the two species to be antagonistic. [8] [9] [10] Other phrases and proverbs include "The cat is mighty dignified until the dog comes by" and "The cat and dog may kiss, but are none the better friends." [11]
Osmoprotectants can be placed in three chemical classes: betaines and associated molecules, sugars and polyols, and amino acids. These molecules accumulate in cells and balance the osmotic difference between the cell's surroundings and the cytosol. [2] In plants, their accumulation can increase survival during stresses such as drought.
The water molecule is amphoteric in aqueous solution. It can either gain a proton to form a hydronium ion H 3 O +, or else lose a proton to form a hydroxide ion OH −. [5] Another possibility is the molecular autoionization reaction between two water molecules, in which one water molecule acts as an acid and another as a base.
Like dogs, cats have sensitive ears that can move independently of each other. Because of this mobility, a cat can move its body in one direction and point its ears in another direction. The rostral, caudal, dorsal, and ventral auricular muscle groups of each ear comprise fifteen muscles that are responsible for this ability. [5]
Pets can't visually make sense of the programs we love. To them, everything looks like one big blur -- but dogs and cats see different things. Grumpy Cat hates TV because, well, Grumpy Cat hates ...
In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. [1] In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thus, prefer other neutral molecules and nonpolar solvents.