Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Hydrophobic hydrocarbon chain

Traditional amphiphiles contain a hydrophilic head group and the hydrophobic hydrocarbon chain(s). The molecules are spread at molecular areas greater (-2-10 times) than that to which they will be compressed. The record of surface pressure (II) versus molecular area (A) at constant temperature as the barrier is moved forward to compress the monolayer is known as an isotherm, which is analogous to P-V isotherms for bulk substances. H-A isotherm data provide information on the molecular packing, the monolayer stability as de-... [Pg.61]

A unique feature of such DNA-directed self-assemblies is their site-selective immobilization, which makes it possible to construct well-defined nanostructures. On the other hand, the possibility of the introduction of a vast number of substitutes (like peptidic sequences, nucleoproteins, of hydrophobic hydrocarbon chains) to an adamantane core (adamantyl) makes such a process capable of designing steric colloidal and supramolecular conformations by setting hydrophobic/hydrophilic and other interactions. In addition, the rigidity of the adamantane structure can provide strength and rigidity to such self-assemblies [150]. [Pg.239]

A conceptualized cross section through a portion of the cell wall (rectangles), periplasmic space, and cell membrane (lipid bilayer with polar head groups in contact with cytoplasm and external medium, and hydrophobic hydrocarbon chains) of an aquatic microbe. Reactive functional groups (-SH, -COOH, -OH, -NH2) present on the wall consitutents and extracellular enzymes (depicted as shaded objects) attached by various means promote and catalyze chemical reactions extracellularly. [Pg.119]

The characteristic feature of a bilayer is that both faces are hydrophilic and are exposed to the aqueous environment. The hydrophobic hydrocarbon chains are hidden away inside the bilayer. Here is the idea ... [Pg.256]

Phospholipids consist of two hydrophobic hydrocarbon chains and a polar head group, ionized and/or sugar groups. Above a critical temperature Tc they swell in... [Pg.153]

C8 (Octyl)—Nonpolar column or packing with 8 carbon hydrophobic hydrocarbon chain bound to silica. [Pg.214]

We have already seen how oils such as glyceryl trioleate form thin layers on water while soaps from the alkaline hydrolysis of glycerides form micelles. Phosphatidyl choline forms yet another structure—it spontaneously forms a membrane in water. The hydrophobic hydrocarbon chains line up together on the inside of the membrane with the hydrophilic choline residues on the outside. [Pg.1377]

EFAs also are polyunsaturated fatty acids (PUFAs) because they contain two or more double bonds. PUFAs are fatty acids, some of which have at least two carbon-to-carbon double bonds in a hydrophobic hydrocarbon chain. At least four independent families of PUFAs exist, depending on the parent fatty acid from which they are synthesized. They include ... [Pg.858]

One of the main functions of lipids is to serve as the main structural components of cell membranes (7). Membranes resemble thin elastic sheets with a total thickness of about 5 nm. The membrane is composed of two lipid monolayers. The lipids in a membrane typically include two nonpolar and hydrophobic (water hating) acyl chains coimected to one another close to the head group, which in turn is usually polar and hydrophilic (water loving) and therefore can form hydrogen bonds with neighboring water molecules. This schizophrenic nature of lipid molecules causes them to self-assemble as closed objects such as liposomes, such that the head groups face water molecules while the hydrophobic hydrocarbon chains are protected from the water phase. [Pg.2242]

The basic structure, a hydrophobic hydrocarbon chain with a hydrophilic polar group at one end, endows fatty acids and their derivatives with distinctive properties, reflected in both their food and industrial use. Saturated fatty acids have a straight hydrocarbon chain. A trans-Aoablt bond is accommodated with httle change in shape, but a cis bond introduces a pronounced bend in the chain (Fig. 1). [Pg.50]

Surfactants produce micelles. Their amphophilic nature classifies them as detergents, surface-active agents that are composed of a hydrophilic group and a hydrophobic hydrocarbon chain. In addition to what is known as the critical micelle concentration (CMC), individual surfactant molecules (monomers) interact with each other to form aggregates or micelles, establishing a state of equilibrium between a constant monomer concentration and a rapidly increasing micelle concentration. [Pg.602]

Stearic acid, C17H35COOH, may be used to provide a monolayer to reduce the rate of water loss by evaporation from the surface of a reservoir. The molecule floats at the surface with the hydrophobic hydrocarbon chain upward and the hydrophilic carboxylic acid downward, and in so doing covers roughly a circular area of radius 2.82 A (0.282 nm) per molecule. How many kilograms of stearic acid would be required to form a solid monolayer over the surface of the Elk Lake reservoir, which covers an area of 289 acres (1 acre = 4,047m )... [Pg.168]

Phospholipids have one polar head group and two hydrophobic hydrocarbon chains ranging from 14 to 24 carbon atoms. In most cases, one of the chains has one or more double bonds (Figure 9.2). Using spin resonance spectroscopy, it can be demonstrated that a distinct lipid molecule changes its position with an adjacent molecule between 10 and 10 times/s. In contrast, a change with a molecule from the opposite membrane leaflet (flip-flop mechanisms) occurs only once per 1-2 weeks. Cholesterol has a significant impact on membrane fluidity hydroxyl... [Pg.231]

Fig. 8.20 Schematic diagram showing the structural changes in a unimolecular film going from the liquid expanded state (Li) through the intermediate state (1) to the liquid condensed state (L2). The hydrophilic head group is designated by the circle at the end of a long hydrophobic hydrocarbon chain. Fig. 8.20 Schematic diagram showing the structural changes in a unimolecular film going from the liquid expanded state (Li) through the intermediate state (1) to the liquid condensed state (L2). The hydrophilic head group is designated by the circle at the end of a long hydrophobic hydrocarbon chain.
Self-sealing capability. When lipid bilayers are disrupted, they immediately and spontaneously reseal (Figure 11.22) because a break in a lipid bilayer exposes the hydrophobic hydrocarbon chains to water. Because breaches in cell membranes can be lethal, this resealing property is critical. (In living cells, certain pro-... [Pg.359]


See other pages where Hydrophobic hydrocarbon chain is mentioned: [Pg.427]    [Pg.343]    [Pg.177]    [Pg.120]    [Pg.43]    [Pg.732]    [Pg.19]    [Pg.152]    [Pg.243]    [Pg.289]    [Pg.27]    [Pg.102]    [Pg.144]    [Pg.179]    [Pg.304]    [Pg.53]    [Pg.250]    [Pg.89]    [Pg.97]    [Pg.83]    [Pg.59]    [Pg.344]    [Pg.493]    [Pg.274]    [Pg.274]    [Pg.36]    [Pg.59]    [Pg.834]    [Pg.169]    [Pg.3]    [Pg.37]    [Pg.825]    [Pg.148]   
See also in sourсe #XX -- [ Pg.462 ]




SEARCH



Hydrophobic chain

© 2024 chempedia.info