Polar in Biological Definition

Lipid

... Structure of a Lipid. Many lipids consists of a polar head group ( P ) and a nonpolar tail ( U for ... while others are rigid. Most lipids have some polar character in addition to being largely nonpolar. ... meaning that it does not interact well with polar solvents like water. Another part of their ...

Alcohol

... properties The hydroxyl group generally makes the alcohol molecule polar . Those groups can form hydrogen bonds to one another and to other compounds. Two opposing solubility trends in alcohols are: the tendency of the polar OH to promote solubility in water, and of the carbon chain to resist it. ...

Cell membrane

... membranes through diffusion of hydrophobic (non polar) and small polar molecules, or facilitated diffusion of polar and ionic molecules, which relies on a transport protein to provide a ...

Meiosis

... signified by contraction and staining of all chromosomes, as well as the polar migration of centrioles , the dispersion of the nucleoli and nuclear ... as the shortening and thickening of the chromatids. Centrioles move to the polar regions and are arranged by spindle fibres. This arrangement is rotated by ...

Cell membrane

... membranes through diffusion of hydrophobic (non polar) and small polar molecules, or facilitated diffusion of polar and ionic molecules, which relies on a transport protein to provide a ...

Amino acid

... specific to each amino acid. Amino acids are usually classified by properties of the side chain into four groups: acidic , basic , hydrophilic ( polar ), and hydrophobic ( nonpolar ). Isomerism Except for glycine , where R = H, amino acids occur in two possible optical isomers , called D ...

Beta sheet

... the adjacent sidechains on one side of the sheet are hydrophobic, while many of those adjacent to each other on the alternate side of the sheet are polar or charged (hydrophilic). Some sequences involved in a β sheet, when traced along the backbone, take a hairpin turn in orientation ...

Biodiversity

... lived on earth are today extinct . Biodiversity is not distributed evenly on earth. It is consistently richer in the tropics. As one approaches polar regions one finds larger and larger populations of fewer and fewer species. Flora and fauna vary depending on climate , altitude, soils and the ...

Bacterium

... have a distinctive helical body that twists about as it moves. Bacterial flagella are arranged in many different ways. Bacteria can have a single polar flagellum at one end of a cell, or they can have clusters of many flagella at one end. Peritrichous bacteria have flagella scattered all over the ...

Biophysics

... , B 173, 1969, pp. 113-140 Dogonadze R.R. and Urushadze Z.D. Semi-Classical Method of Calculation of Rates of Chemical Reactions Proceeding in polar Liquids.- J.Electroanal.Chem. , 32, 1971, pp. 235-245 Volkenshtein M.V., Dogonadze R.R., Madumarov A.K., Urushadze Z.D. and Kharkats Yu.I. Theory ...

Carnivore

... are carnivores or omnivores, but wild dogs such as coyotes and wolves etc.) Hyenas and other scavengers Weasels Some skunks polar Bears Birds of prey , including hawks , eagles , and falcons Owls Scavenger birds, like vultures Several species of waterfowl ...

Bacterium

... have a distinctive helical body that twists about as it moves. Bacterial flagella are arranged in many different ways. Bacteria can have a single polar flagellum at one end of a cell, or they can have clusters of many flagella at one end. Peritrichous bacteria have flagella scattered all over the ...

Flagellum

... space , the rotation of which causes the entire bacterium to corkscrew through its usually viscous medium. Anticlockwise rotation of monotrichous polar flagella thrusts the cell forward with the flagellum trailing behind. Periodically the direction of rotation is briefly reversed, causing what is ...

Marine biology

... ) are all considered pinnipeds . Sea Otters are members of the Family Mustelidae , which includes weasels and badgers . Finally, polar Bears (Family Ursidae ) are sometimes considered marine mammals because of their dependence on the sea. In the USA they are protected under marine ...

Peripheral membrane protein

... lipid bilayer core of the membrane, but attach indirectly, typically by binding to integral membrane proteins , or by interactions with the lipid polar head. Therefore the so-called regulatory protein subunits of many ion channels and transmembrane receptors , for example, may be defined as ...

Phospholipid

... is present in all eukaryotic cell membranes , but is mainly present in cells of the nervous system. Amphiphatic character Due to its polar nature, the head of a phospholipid is attracted to water (it is hydrophilic ). The nonpolar head is not attracted to water and is said to be ...

Lipid bilayer

... of lipid molecules arranged so that their hydrocarbon tails face one another to form the oily bilayer core, while their electrically charged or polar heads face the watery or "aqueous" solutions on either side of the membrane. Because of the oily core, a pure lipid bilayer is permeable to small ...

Red Queen

... of a simple example of a biological arms race (from Richard Dawkins ) can be achieved by considering the contrast between two adaptations of the polar bear . This animal has a coat of hair which is thick to help the bear survive the cold of the arctic and white in order that the bear can stalk ...

Tubulin

... from dimers of α- and β-tubulin. Each of these subunits has three domains . γ-tubulin is important in the nucleation and polar orientation of microtubule. Tubulin binds GTP and assembles onto the (+) ends of microtubules in the GTP-bound state. Once assembled into ...