Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Lipid Bilayers: Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.Membrane Lipids: Lipids, predominantly phospholipids, cholesterol and small amounts of glycolipids found in membranes including cellular and intracellular membranes. These lipids may be arranged in bilayers in the membranes with integral proteins between the layers and peripheral proteins attached to the outside. Membrane lipids are required for active transport, several enzymatic activities and membrane formation.Membranes: Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.Membranes, Artificial: Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION.Membrane Fluidity: The motion of phospholipid molecules within the lipid bilayer, dependent on the classes of phospholipids present, their fatty acid composition and degree of unsaturation of the acyl chains, the cholesterol concentration, and temperature.Intracellular Membranes: Thin structures that encapsulate subcellular structures or ORGANELLES in EUKARYOTIC CELLS. They include a variety of membranes associated with the CELL NUCLEUS; the MITOCHONDRIA; the GOLGI APPARATUS; the ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.Membrane Potentials: The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).Erythrocyte Membrane: The semi-permeable outer structure of a red blood cell. It is known as a red cell 'ghost' after HEMOLYSIS.Cell Membrane Permeability: A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.Phosphatidylcholines: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a choline moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and choline and 2 moles of fatty acids.Liposomes: Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.Basement Membrane: A darkly stained mat-like EXTRACELLULAR MATRIX (ECM) that separates cell layers, such as EPITHELIUM from ENDOTHELIUM or a layer of CONNECTIVE TISSUE. The ECM layer that supports an overlying EPITHELIUM or ENDOTHELIUM is called basal lamina. Basement membrane (BM) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. BM, composed mainly of TYPE IV COLLAGEN; glycoprotein LAMININ; and PROTEOGLYCAN, provides barriers as well as channels between interacting cell layers.Molecular Conformation: The characteristic three-dimensional shape of a molecule.1,2-Dipalmitoylphosphatidylcholine: Synthetic phospholipid used in liposomes and lipid bilayers to study biological membranes. It is also a major constituent of PULMONARY SURFACTANTS.Dimyristoylphosphatidylcholine: A synthetic phospholipid used in liposomes and lipid bilayers for the study of biological membranes.Microscopy, Electron: Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Membrane Transport Proteins: Membrane proteins whose primary function is to facilitate the transport of molecules across a biological membrane. Included in this broad category are proteins involved in active transport (BIOLOGICAL TRANSPORT, ACTIVE), facilitated transport and ION CHANNELS.Phospholipids: Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Phosphatidylethanolamines: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to an ethanolamine moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and ethanolamine and 2 moles of fatty acids.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Membrane Glycoproteins: Glycoproteins found on the membrane or surface of cells.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Water: A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Protein Transport: The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Ion Channels: Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Diffusion: The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Protein Structure, Tertiary: The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.Phosphatidylglycerols: A nitrogen-free class of lipids present in animal and particularly plant tissues and composed of one mole of glycerol and 1 or 2 moles of phosphatidic acid. Members of this group differ from one another in the nature of the fatty acids released on hydrolysis.Cholesterol: The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.Phase Transition: A change of a substance from one form or state to another.Gramicidin: A group of peptide antibiotics from BACILLUS brevis. Gramicidin C or S is a cyclic, ten-amino acid polypeptide and gramicidins A, B, D are linear. Gramicidin is one of the two principal components of TYROTHRICIN.Calorimetry, Differential Scanning: Differential thermal analysis in which the sample compartment of the apparatus is a differential calorimeter, allowing an exact measure of the heat of transition independent of the specific heat, thermal conductivity, and other variables of the sample.Detergents: Purifying or cleansing agents, usually salts of long-chain aliphatic bases or acids, that exert cleansing (oil-dissolving) and antimicrobial effects through a surface action that depends on possessing both hydrophilic and hydrophobic properties.Freeze Fracturing: Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.Kinetics: The rate dynamics in chemical or physical systems.Phosphatidylserines: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a serine moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and serine and 2 moles of fatty acids.Unilamellar Liposomes: Single membrane vesicles, generally made of PHOSPHOLIPIDS.Thermodynamics: A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)Mitochondrial Membranes: The two lipoprotein layers in the MITOCHONDRION. The outer membrane encloses the entire mitochondrion and contains channels with TRANSPORT PROTEINS to move molecules and ions in and out of the organelle. The inner membrane folds into cristae and contains many ENZYMES important to cell METABOLISM and energy production (MITOCHONDRIAL ATP SYNTHASE).Permeability: Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.Hydrophobic and Hydrophilic Interactions: The thermodynamic interaction between a substance and WATER.Protein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Electric Conductivity: The ability of a substrate to allow the passage of ELECTRONS.Biophysics: The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.Models, Chemical: Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.Biophysical Phenomena: The physical characteristics and processes of biological systems.Alamethicin: A cyclic nonadecapeptide antibiotic that can act as an ionophore and is produced by strains of Trichoderma viride. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Microscopy, Fluorescence: Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.Protein Structure, Secondary: The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.Spectrometry, Fluorescence: Measurement of the intensity and quality of fluorescence.Fluorescent Dyes: Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Synaptic Membranes: Cell membranes associated with synapses. Both presynaptic and postsynaptic membranes are included along with their integral or tightly associated specializations for the release or reception of transmitters.Carrier Proteins: Transport proteins that carry specific substances in the blood or across cell membranes.Peptides: Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.Cell Membrane Structures: Structures which are part of the CELL MEMBRANE or have cell membrane as a major part of their structure.Bacterial Proteins: Proteins found in any species of bacterium.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Potassium: An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.Membrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Sphingomyelins: A class of sphingolipids found largely in the brain and other nervous tissue. They contain phosphocholine or phosphoethanolamine as their polar head group so therefore are the only sphingolipids classified as PHOSPHOLIPIDS.Cell Fractionation: Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Lipids: A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed)Solubility: The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Surface Properties: Characteristics or attributes of the outer boundaries of objects, including molecules.Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Time Factors: Elements of limited time intervals, contributing to particular results or situations.Biological Transport, Active: The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.Microscopy, Confocal: A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.Molecular Weight: The sum of the weight of all the atoms in a molecule.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Endoplasmic Reticulum: A system of cisternae in the CYTOPLASM of many cells. In places the endoplasmic reticulum is continuous with the plasma membrane (CELL MEMBRANE) or outer membrane of the nuclear envelope. If the outer surfaces of the endoplasmic reticulum membranes are coated with ribosomes, the endoplasmic reticulum is said to be rough-surfaced (ENDOPLASMIC RETICULUM, ROUGH); otherwise it is said to be smooth-surfaced (ENDOPLASMIC RETICULUM, SMOOTH). (King & Stansfield, A Dictionary of Genetics, 4th ed)Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Micelles: Particles consisting of aggregates of molecules held loosely together by secondary bonds. The surface of micelles are usually comprised of amphiphatic compounds that are oriented in a way that minimizes the energy of interaction between the micelle and its environment. Liquids that contain large numbers of suspended micelles are referred to as EMULSIONS.Octoxynol: Nonionic surfactant mixtures varying in the number of repeating ethoxy (oxy-1,2-ethanediyl) groups. They are used as detergents, emulsifiers, wetting agents, defoaming agents, etc. Octoxynol-9, the compound with 9 repeating ethoxy groups, is a spermatocide.Cytoplasm: The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)Sodium: A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.Recombinant Fusion Proteins: Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.Golgi Apparatus: A stack of flattened vesicles that functions in posttranslational processing and sorting of proteins, receiving them from the rough ENDOPLASMIC RETICULUM and directing them to secretory vesicles, LYSOSOMES, or the CELL MEMBRANE. The movement of proteins takes place by transfer vesicles that bud off from the rough endoplasmic reticulum or Golgi apparatus and fuse with the Golgi, lysosomes or cell membrane. (From Glick, Glossary of Biochemistry and Molecular Biology, 1990)Melitten: Basic polypeptide from the venom of the honey bee (Apis mellifera). It contains 26 amino acids, has cytolytic properties, causes contracture of muscle, releases histamine, and disrupts surface tension, probably due to lysis of cell and mitochondrial membranes.Static Electricity: The accumulation of an electric charge on a objectMathematics: The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)X-Ray Diffraction: The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Cricetinae: A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.Endocytosis: Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. ENDOSOMES play a central role in endocytosis.Fluorescence Polarization: Measurement of the polarization of fluorescent light from solutions or microscopic specimens. It is used to provide information concerning molecular size, shape, and conformation, molecular anisotropy, electronic energy transfer, molecular interaction, including dye and coenzyme binding, and the antigen-antibody reaction.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.Porins: Porins are protein molecules that were originally found in the outer membrane of GRAM-NEGATIVE BACTERIA and that form multi-meric channels for the passive DIFFUSION of WATER; IONS; or other small molecules. Porins are present in bacterial CELL WALLS, as well as in plant, fungal, mammalian and other vertebrate CELL MEMBRANES and MITOCHONDRIAL MEMBRANES.Structure-Activity Relationship: The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.Molecular Dynamics Simulation: A computer simulation developed to study the motion of molecules over a period of time.Signal Transduction: The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Adenosine Triphosphate: An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.Subcellular Fractions: Components of a cell produced by various separation techniques which, though they disrupt the delicate anatomy of a cell, preserve the structure and physiology of its functioning constituents for biochemical and ultrastructural analysis. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p163)Microvilli: Minute projections of cell membranes which greatly increase the surface area of the cell.Hemolysis: The destruction of ERYTHROCYTES by many different causal agents such as antibodies, bacteria, chemicals, temperature, and changes in tonicity.Diphenylhexatriene: A fluorescent compound that emits light only in specific configurations in certain lipid media. It is used as a tool in the study of membrane lipids.Electrochemistry: The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.Fluorescent Antibody Technique: Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.Extraembryonic Membranes: The thin layers of tissue that surround the developing embryo. There are four extra-embryonic membranes commonly found in VERTEBRATES, such as REPTILES; BIRDS; and MAMMALS. They are the YOLK SAC, the ALLANTOIS, the AMNION, and the CHORION. These membranes provide protection and means to transport nutrients and wastes.Microscopy, Atomic Force: A type of scanning probe microscopy in which a probe systematically rides across the surface of a sample being scanned in a raster pattern. The vertical position is recorded as a spring attached to the probe rises and falls in response to peaks and valleys on the surface. These deflections produce a topographic map of the sample.Mitochondria: Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Spin Labels: Molecules which contain an atom or a group of atoms exhibiting an unpaired electron spin that can be detected by electron spin resonance spectroscopy and can be bonded to another molecule. (McGraw-Hill Dictionary of Chemical and Technical Terms, 4th ed)Anions: Negatively charged atoms, radicals or groups of atoms which travel to the anode or positive pole during electrolysis.2-Naphthylamine: A naphthalene derivative with carcinogenic action.Escherichia coli Proteins: Proteins obtained from ESCHERICHIA COLI.Anion Exchange Protein 1, Erythrocyte: A major integral transmembrane protein of the ERYTHROCYTE MEMBRANE. It is the anion exchanger responsible for electroneutral transporting in CHLORIDE IONS in exchange of BICARBONATE IONS allowing CO2 uptake and transport from tissues to lungs by the red blood cells. Genetic mutations that result in a loss of the protein function have been associated with type 4 HEREDITARY SPHEROCYTOSIS.Chlorides: Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.Cytosol: Intracellular fluid from the cytoplasm after removal of ORGANELLES and other insoluble cytoplasmic components.Laurates: Salts and esters of the 12-carbon saturated monocarboxylic acid--lauric acid.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Electron Spin Resonance Spectroscopy: A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.Blotting, Western: Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.Osmosis: Tendency of fluids (e.g., water) to move from the less concentrated to the more concentrated side of a semipermeable membrane.Transfection: The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.Cations: Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.Adsorption: The adhesion of gases, liquids, or dissolved solids onto a surface. It includes adsorptive phenomena of bacteria and viruses onto surfaces as well. ABSORPTION into the substance may follow but not necessarily.Surface-Active Agents: Agents that modify interfacial tension of water; usually substances that have one lipophilic and one hydrophilic group in the molecule; includes soaps, detergents, emulsifiers, dispersing and wetting agents, and several groups of antiseptics.Peptide Fragments: Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.Spectrin: A high molecular weight (220-250 kDa) water-soluble protein which can be extracted from erythrocyte ghosts in low ionic strength buffers. The protein contains no lipids or carbohydrates, is the predominant species of peripheral erythrocyte membrane proteins, and exists as a fibrous coating on the inner, cytoplasmic surface of the membrane.CHO Cells: CELL LINE derived from the ovary of the Chinese hamster, Cricetulus griseus (CRICETULUS). The species is a favorite for cytogenetic studies because of its small chromosome number. The cell line has provided model systems for the study of genetic alterations in cultured mammalian cells.Electrophysiology: The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.Cytoskeleton: The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.Exocytosis: Cellular release of material within membrane-limited vesicles by fusion of the vesicles with the CELL MEMBRANE.Freeze Etching: A replica technique in which cells are frozen to a very low temperature and cracked with a knife blade to expose the interior surfaces of the cells or cell membranes. The cracked cell surfaces are then freeze-dried to expose their constituents. The surfaces are now ready for shadowing to be viewed using an electron microscope. This method differs from freeze-fracturing in that no cryoprotectant is used and, thus, allows for the sublimation of water during the freeze-drying process to etch the surfaces.Microscopy, Immunoelectron: Microscopy in which the samples are first stained immunocytochemically and then examined using an electron microscope. Immunoelectron microscopy is used extensively in diagnostic virology as part of very sensitive immunoassays.Receptors, Cell Surface: Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.Porosity: Condition of having pores or open spaces. This often refers to bones, bone implants, or bone cements, but can refer to the porous state of any solid substance.Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Macromolecular Substances: Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.Proteolipids: Protein-lipid combinations abundant in brain tissue, but also present in a wide variety of animal and plant tissues. In contrast to lipoproteins, they are insoluble in water, but soluble in a chloroform-methanol mixture. The protein moiety has a high content of hydrophobic amino acids. The associated lipids consist of a mixture of GLYCEROPHOSPHATES; CEREBROSIDES; and SULFOGLYCOSPHINGOLIPIDS; while lipoproteins contain PHOSPHOLIPIDS; CHOLESTEROL; and TRIGLYCERIDES.Scattering, Radiation: The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Microscopy, Electron, Scanning: Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.Fluoresceins: A family of spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one derivatives. These are used as dyes, as indicators for various metals, and as fluorescent labels in immunoassays.Ions: An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.Polyethylene Glycols: Polymers of ETHYLENE OXIDE and water, and their ethers. They vary in consistency from liquid to solid depending on the molecular weight indicated by a number following the name. They are used as SURFACTANTS, dispersing agents, solvents, ointment and suppository bases, vehicles, and tablet excipients. Some specific groups are NONOXYNOLS, OCTOXYNOLS, and POLOXAMERS.Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.Quaternary Ammonium Compounds: Derivatives of ammonium compounds, NH4+ Y-, in which all four of the hydrogens bonded to nitrogen have been replaced with hydrocarbyl groups. These are distinguished from IMINES which are RN=CR2.beta-Cyclodextrins: Cyclic GLUCANS consisting of seven (7) glucopyranose units linked by 1,4-glycosidic bonds.Green Fluorescent Proteins: Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.Vacuoles: Any spaces or cavities within a cell. They may function in digestion, storage, secretion, or excretion.Tetraphenylborate: An anionic compound that is used as a reagent for determination of potassium, ammonium, rubidium, and cesium ions. It also uncouples oxidative phosphorylation and forms complexes with biological materials, and is used in biological assays.Membrane Microdomains: Detergent-insoluble CELL MEMBRANE components. They are enriched in SPHINGOLIPIDS and CHOLESTEROL and clustered with glycosyl-phosphatidylinositol (GPI)-anchored proteins.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Microscopy, Electron, Transmission: Electron microscopy in which the ELECTRONS or their reaction products that pass down through the specimen are imaged below the plane of the specimen.Actins: Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.Ergosterol: A steroid of interest both because its biosynthesis in FUNGI is a target of ANTIFUNGAL AGENTS, notably AZOLES, and because when it is present in SKIN of animals, ULTRAVIOLET RAYS break a bond to result in ERGOCALCIFEROL.Ion Channel Gating: The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.Membrane Potential, Mitochondrial: The voltage difference, normally maintained at approximately -180mV, across the INNER MITOCHONDRIAL MEMBRANE, by a net movement of positive charge across the membrane. It is a major component of the PROTON MOTIVE FORCE in MITOCHONDRIA used to drive the synthesis of ATP.HeLa Cells: The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.Glycoproteins: Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.Immunoblotting: Immunologic method used for detecting or quantifying immunoreactive substances. The substance is identified by first immobilizing it by blotting onto a membrane and then tagging it with labeled antibodies.Spectroscopy, Fourier Transform Infrared: A spectroscopic technique in which a range of wavelengths is presented simultaneously with an interferometer and the spectrum is mathematically derived from the pattern thus obtained.Endosomes: Cytoplasmic vesicles formed when COATED VESICLES shed their CLATHRIN coat. Endosomes internalize macromolecules bound by receptors on the cell surface.COS Cells: CELL LINES derived from the CV-1 cell line by transformation with a replication origin defective mutant of SV40 VIRUS, which codes for wild type large T antigen (ANTIGENS, POLYOMAVIRUS TRANSFORMING). They are used for transfection and cloning. (The CV-1 cell line was derived from the kidney of an adult male African green monkey (CERCOPITHECUS AETHIOPS).)Osmolar Concentration: The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.Patch-Clamp Techniques: An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.Elasticity: Resistance and recovery from distortion of shape.Glycolipids: Any compound containing one or more monosaccharide residues bound by a glycosidic linkage to a hydrophobic moiety such as an acylglycerol (see GLYCERIDES), a sphingoid, a ceramide (CERAMIDES) (N-acylsphingoid) or a prenyl phosphate. (From IUPAC's webpage)Sodium-Potassium-Exchanging ATPase: An enzyme that catalyzes the active transport system of sodium and potassium ions across the cell wall. Sodium and potassium ions are closely coupled with membrane ATPase which undergoes phosphorylation and dephosphorylation, thereby providing energy for transport of these ions against concentration gradients.Purple Membrane: Functionally and structurally differentiated, purple-pigmented regions of the cytoplasmic membrane of some strains of Halobacterium halobium. The membrane develops under anaerobic conditions and is made almost entirely of the purple pigment BACTERIORHODOPSINS. (From Singleton & Sainsbury Dictionary of Microbiology and Molecular Biology, 2d ed)Circular Dichroism: A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Epithelium: One or more layers of EPITHELIAL CELLS, supported by the basal lamina, which covers the inner or outer surfaces of the body.Glycosylphosphatidylinositols: Compounds containing carbohydrate or glycosyl groups linked to phosphatidylinositols. They anchor GPI-LINKED PROTEINS or polysaccharides to cell membranes.Fluorescence: The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.Membrane Fusion: The adherence and merging of cell membranes, intracellular membranes, or artificial membranes to each other or to viruses, parasites, or interstitial particles through a variety of chemical and physical processes.Epithelial Cells: Cells that line the inner and outer surfaces of the body by forming cellular layers (EPITHELIUM) or masses. Epithelial cells lining the SKIN; the MOUTH; the NOSE; and the ANAL CANAL derive from ectoderm; those lining the RESPIRATORY SYSTEM and the DIGESTIVE SYSTEM derive from endoderm; others (CARDIOVASCULAR SYSTEM and LYMPHATIC SYSTEM) derive from mesoderm. Epithelial cells can be classified mainly by cell shape and function into squamous, glandular and transitional epithelial cells.Enzyme Activation: Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.GTP-Binding Proteins: Regulatory proteins that act as molecular switches. They control a wide range of biological processes including: receptor signaling, intracellular signal transduction pathways, and protein synthesis. Their activity is regulated by factors that control their ability to bind to and hydrolyze GTP to GDP. EC 3.6.1.-.Protons: Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.Fatty Acids: Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)Binding, Competitive: The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements.Potassium Channels: Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.Cardiolipins: Acidic phospholipids composed of two molecules of phosphatidic acid covalently linked to a molecule of glycerol. They occur primarily in mitochondrial inner membranes and in bacterial plasma membranes. They are the main antigenic components of the Wassermann-type antigen that is used in nontreponemal SYPHILIS SERODIAGNOSIS.Proteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Ion Transport: The movement of ions across energy-transducing cell membranes. Transport can be active, passive or facilitated. Ions may travel by themselves (uniport), or as a group of two or more ions in the same (symport) or opposite (antiport) directions.Protein Sorting Signals: Amino acid sequences found in transported proteins that selectively guide the distribution of the proteins to specific cellular compartments.Aquaporins: A class of porins that allow the passage of WATER and other small molecules across CELL MEMBRANES.Phosphatidylinositols: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to the hexahydroxy alcohol, myo-inositol. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid, myo-inositol, and 2 moles of fatty acids.4-Chloro-7-nitrobenzofurazan: A benzofuran derivative used as a protein reagent since the terminal N-NBD-protein conjugate possesses interesting fluorescence and spectral properties. It has also been used as a covalent inhibitor of both beef heart mitochondrial ATPase and bacterial ATPase.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Antibodies, Monoclonal: Antibodies produced by a single clone of cells.Surface Tension: The force acting on the surface of a liquid, tending to minimize the area of the surface. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Cercopithecus aethiops: A species of CERCOPITHECUS containing three subspecies: C. tantalus, C. pygerythrus, and C. sabeus. They are found in the forests and savannah of Africa. The African green monkey (C. pygerythrus) is the natural host of SIMIAN IMMUNODEFICIENCY VIRUS and is used in AIDS research.Magnesium: A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
The lipid bilayer of an endothelial cell membrane is a hydrophobic surface. The non-polar lipids lead to a very high electrical ... membrane Rmem is the specific membrane resistance A is the area This high resistivity prevents ions from crossing the bilayer ... Larger molecules and blood cells require adequate space between cells or holes in the lining. The high resistivity of a ... through gaps between the cells or directly through the cells. Molecules diffuse through the capillary walls due to ...
... gla residues are needed in calcium binding and in exposing hydrophobic membrane binding regions to the cell bilayer. Lack of ... a cell-associated tissue factor becomes exposed and initiates a series of enzymatic reactions localized on a membrane surface ... partly govern the activation and binding of circulating blood-clotting enzymes and zymogens to this exposed cell membrane ... generally provided by cells and accumulating platelets. Gla residues ...
... in a bilayer such as a cell membrane. Lipid bilayers occur when hydrophobic tails line up against one another, forming a ... Phospholipids are a class of lipids that are a major component of all cell membranes. They can form lipid bilayers because of ... Sterols contribute to membrane fluidity by hindering the packing together of phospholipids. However, this model has now been ... Such movement can be described by the fluid mosaic model, that describes the membrane as a mosaic of lipid molecules that act ...
To accomplish this task, ions must be able to cross the hydrophobic region of a lipid bilayer membrane, an unfavorable process ... Their main function is to contribute to the resting membrane potential of a cell via the flow of ions through a cell membrane. ... Ion channels permit the selective passage of ions through cell membranes by utilizing proteins that function as pores, which ... They are expressed primarily in apical membranes of epithelial cells in respiratory, pancreatic, gastrointestinal, and ...
This structure allows pepducin lipopeptides to anchor in the cell membrane lipid bilayer and target the GPCR/G protein ... A pepducin molecule consists of a short peptide derived from a GPCR intracellular loop tethered to a hydrophobic moiety. ... "Activation and inhibition of G protein-coupled receptors by cell-penetrating membrane-tethered peptides". Proc. Natl. Acad. Sci ... Pepducins are cell-penetrating peptides that act as intracellular modulators of signal transference from receptors to G ...
... of the cell membrane, thereby placing the membrane in a less fluid, more crystalline state. (In ordinary circumstances membrane ... sterols increase the packing of the phospholipid bilayer making the plasma membrane more dense.) As a result, the cell's ... As a polyene's hydrophobic chain is shortened, its sterol binding activity is increased. Therefore, further reduction of the ... Miltefosine disrupts fungal cell membrane dynamics by interacting with ergosterol [18]. *Potassium iodide is the preferred ...
To deliver the molecules to a site of action, the lipid bilayer can fuse with other bilayers such as the cell membrane, thus ... A liposome has an aqueous solution core surrounded by a hydrophobic membrane, in the form of a lipid bilayer; hydrophilic ... Hydrophobic chemicals associate with the bilayer. A liposome can be hence loaded with hydrophobic and/or hydrophilic molecules ... "Cell Membranes." Cevc, G (1993). "Rational design of new product candidates: the next generation of highly deformable bilayer ...
Membran sel (bahasa Inggris: cell membrane, plasma membrane, plasmalemma) adalah fitur universal yang dimiliki oleh semua jenis ... "Physical behavior of the hydrophobic core of membranes: properties of 1-stearoyl-2-linoleoyl-sn-glycerol". Department of ... Transpor pasif air dilakukan lipid bilayer dan transpor pasif glukosa terfasilitasi transporter. Ion polar berdifusi dengan ... 2008). "Membrane lipids: where they are and how they behave". Nature Reviews. Molecular Cell Biology 9 (2): 112-24. PMID ...
The cell membrane of nearly all organisms is primarily made up of a phospholipid bilayer, a micelle of hydrophobic fatty acid ... expelling the excess CO2 and resupplying the cells with O2. Cell membranes are generally impermeable to charged or large, polar ... Cell membranes contain fatty acid esters such as phospholipids. An α-amino acid has a central carbon (the α or alpha carbon) ... certain acids will exist in their neutral form and will be membrane soluble, allowing them to cross the phospholipid bilayer. ...
Biological membranes are found in both prokaryotic and eukaryotic cells. They surround cells and organelles with a semi- ... For example, if the hydrophilic region and hydrophobic region are similar, a cylindrical shape lipid bilayer is formed; but ... "Interaction of Ethanol with Biological Membranes: The Formation of Non-Bilayer Structures within the Membrane Interior and ... of cholesterol for each model membrane. In this study, phospholipid membrane is comparable to the model membrane which consists ...
... while the hydrophobic regions are within the phospholipid bilayer of the cell membrane. The cell membrane consists of lipids ... Cell movement - Cell migration, Chemotaxis, contraction, cilia and flagella. Cell signaling - Regulation of cell behavior by ... plasma membrane) - the part of the cell which separates the cells from the outside environment and protects the cell, as well ... Prokaryotic cell The American Society for Cell Biology Cell physiology Lodish, Harvey (2013). Molecular Cell Biology. W. H. ...
It is used to investigate membrane qualities of the phospholipid bilayers of cell membranes. One of its most important ... more particularly about cell's plasmatic membrane's dynamics. The hydrophobic tail of the fatty acid allows the solubilization ... M. A.; Magee A. I. (2007). "Optical techniques for imaging membrane lipid microdomains in living cells". Cell Dev. Biol. 18 (5 ... to observe the membrane lipid bilayer because of their interaction with other compounds within the membrane lipid bilayer. ...
Cell membranes are essentially lipid bilayers which form a semipermeable membrane. Pure lipid bilayers are generally permeable ... is made up of two layers of phospholipids in which the charged hydrophilic heads face outwards and the non-charged hydrophobic ... Since non-ionic species diffuse more readily through cell membranes, weak acids will have a higher absorption in the highly ... passively diffuse through the gastrointestinal tract because the epithelial cell membrane is made up of a phospholipid bilayer ...
The envelope, a lipid bilayer derived from the host-cell plasma membrane, harbours multiple copies of a number of glycoproteins ... The typing scheme is based on the sequence of the small hydrophobic (SH) gene. There are several subgenotypes (D1, D2 G1, G2, ... and lipids allows a single virus to bind to and infect specific cells and replicate itself and finally exit the cell to be ... The mumps virus can infect ependymal cells in the central nervous system. Several strains are used to vaccinate against mumps. ...
C8 alpha-gamma has the hydrophobic area that inserts into the bilayer. C8 alpha-gamma induces the polymerization of 10-16 ... These channels disrupt the cell membrane of target cells, leading to cell lysis and death.[1][2][3] ... The ring structure formed by C9 is a pore in the membrane that allows free diffusion of molecules in and out of the cell. If ... MAC has a hydrophobic external face allowing it to associate with the lipid bilayer. ...
... as these compounds catalyze ion transport across hydrophobic membranes such as liquid polymeric membranes (carrier-based ion ... or lipid bilayers found in the living cells or synthetic vesicles (liposomes) Some ionophores are synthesized by microorganisms ... This makes it easier for the ion to pass through the hydrophobic interior of the lipid membrane. An example of a carrier ... Many ionophores are lipid-soluble entities that transport ions across a cell membrane. Ionophore means "ion carrier" ...
... s which attack eukaryotic cells' bilayer membranes by dissolving their phospholipids. Representative cytolysins of ... Cytolysins which attack the hydrophobic regions of membranes and act like "detergents". Examples of this type include the 26- ... which creates membrane holes on eukaryotic cells. A detailed model of membrane channel formation that reveals membrane ... Attacked cells therefore expand to lysis. When target cell membranes are destructed, bacteria which produce the cytolysins can ...
They possess an important characteristic for the construction of cell membranes; they can come together to form a bilayer ... and a hydrophobic tail on the other. ... If the molecule is enclosed in a cell membrane, then the ... but a lipid bilayer bubble [1] can contain water, and was a likely precursor to the modern cell membrane.[citation needed] If a ... Evolution of cells refers to the evolutionary origin and subsequent evolutionary development of cells. Cells first emerged at ...
... cell membranes and vesicles formation, protein folding, insertion of membrane proteins into the nonpolar lipid environment and ... are composed of amphiphiles that allow hydrophobic molecules to be solubilized in water by forming micelles and bilayers (as in ... Tanford C (1973). The hydrophobic effect: formation of micelles and biological membranes. New York: Wiley. ISBN 978-0-471-84460 ... The origin of the hydrophobic effect is not fully understood. Some argue that the hydrophobic interaction is mostly an entropic ...
... the same membrane protein can be encountered in bilayers of different thickness. In eukaryotic cells, the plasma membrane is ... When the hydrophobic part of a transmembrane protein is too small to match the hydrophobic bilayer thickness (right part of ... Relatively small hydrophobic peptides may not be able to integrate into the membrane, and in response adopt an orientation at ... Hydrophobicity scales Cell membrane Lipid raft Duque, D.; Li, X. J.; Katsov, K.; Schick, M. J. Chem. Phys. 2002, 116, 10478- ...
Immersed in the bi-layer and held in place by the affinity of hydrophobic parts of the protein for the hydrophobic tails of ... Cell biology Cell theory History of cell membrane theory Membrane protein "Membrane - An Introduction" (PDF). Wiley-VCH. ... It has two key features-a mosaic of proteins embedded in the membrane, and the membrane being a fluid bi-layer of lipids. The ... They simply hypothesized that if the plasma membrane is a bi-layer, then the surface area of the mono-layer of lipids measured ...
... the cell membrane (also known as the plasma membrane). Many prokaryotes also have a cell wall, but the cell wall is composed of ... The hydrophobic core of the bilayer is typically 3-4 nm thick, but this value varies with chain length and chemistry. Core ... The cell membranes of almost all living organisms and many viruses are made of a lipid bilayer, as are the membranes ... The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes are ...
... such as the efflux pumps that pump drugs out of a cell. The hydrophobic core of the phospholipid bilayer is constantly in ... Biological membranes, in the form of eukaryotic cell membranes, consist of a phospholipid bilayer with embedded, integral and ... The cell membranes are different from the isolating tissues formed by layers of cells, such as mucous membranes, basement ... and the cell membrane separates a cell from its surrounding medium. Peroxisomes are one form of vacuole found in the cell that ...
Hydrophobic interactions (also known as the hydrophobic effect) are the major driving forces in the formation of lipid bilayers ... damage to cell membrane Cell theory Cytoneme Elasticity of cell membranes Gram-positive bacteria Membrane models Membrane ... plasmatic membrane (Pfeffer, 1900), plasma membrane, cytoplasmic membrane, cell envelope and cell membrane. Some authors that ... The basic function of the cell membrane is to protect the cell from its surroundings. The cell membrane controls the movement ...
... across cell membranes due to the hydrophobic nature of the fatty acid tails of the phospholipids that make up the bilayers. The ... GLUT1 is a named carrier protein found in almost all animal cell membranes that transports glucose across the bilayer. Other ... Each carrier protein, even within the same cell membrane, is specific to one type or family of molecules. For example, ... Facilitated diffusion occurs in and out of the cell membrane via channels/pores and carriers/porters. Note: Channels: Channels ...
The part of the protein that is embedded in the hydrophobic regions of the bilayer are alpha helical and composed of ... The C terminal end of the protein is in the cytosol while the N terminal region is in the outside of the cell. A membrane that ... An integral membrane protein (IMP) is a type of membrane protein that is permanently attached to the biological membrane. All ... Single-pass membrane proteins cross the membrane only once, while multi-pass membrane proteins weave in and out, crossing ...
Phospholipids, bilayer. Hydrophilic head, hydrophobic tail 19 Describe two roles of cell membranes ... Describe one method for inserting DNA into a cell (the cell can be either a prokaryotic or eukaryotic cell). ... What molecules are found in all cell membranes and how are they organized, that is, how does one know which side of the ... Be sure to place each step in the appropriate compartment of the cell. ...
Cell Membrane Tutorial and Problem Set,/li, ,li,Self-Assembly of Real Cell Membranes,/li, ,li,Make a Mummy,/li, ,li,The Osmosis ... The Cell; Genetics; Mechanisms of Evolution; The Evolutionary History of Biological Diversity; Plant Form and Function; Animal ... Membrane Structure and Function contains external links to:,p/, ,ul class=star, ,li, ... Penetrating lipid bilayer 13. Cell junctions 14. Energy requirements for transport 15. Oral rehydration 16. Membrane flow This ...
Technical Abstract: Aquaporins regulate water transport through the highly hydrophobic lipid bilayer of cell membranes. As ... Interpretive Summary: Aquaporins regulate water transport through cell membranes enclosing the cells of higher organisms. As ...
phospholipid bilayer cell membranes (made up of fatty acids and alcohol). Composed of a hydrophilic head and a hydrophobic ... Mitochondria and chloroplasts have cell membranes just like prokaryotic cells do. Organelles have their own DNA, RNA and ... The "enclosure" of some prokaryotic cells by other larger prokaryotic cells (one cell lives inside the other) ... self replicating machinery gets enclosed in a membrane, true cells with rna arise, modern cell DNA replaces RNa. ...
... as well as to modifications of the plasma membrane bilayer composition in lung cells [76, 77]. ... Caveolins attach to the cytosolic face of the membrane via a hydrophobic hairpin loop and via a scaffolding region that ... C. E. Morris and U. Homann, "Cell surface area regulation and membrane tension," Journal of Membrane Biology, vol. 179, no. 2, ... Membrane rafts (MRs) represent specialized portions of the cell plasma membrane involved in the signalling response to incoming ...
This makes the cell membrane selectively permeable. 1 negative polar hydrophilic head, 2 hydrophobic nonpolar tails ... What does it mean to have a phospholipid bilayer?. ... Animal Cell vs. Plant Cell:. Just Plant Cell: Cell Wall, ... A. cells are less complex, B. Unicellular, C. no nucleus & no membrane-bound organelles, D. Cell wall surrounding cell membrane ... function of the cell membrane that lets certain things pass through the membrane by diffusion in active transport but keeps ...
The lipid bilayer of an endothelial cell membrane is a hydrophobic surface. The non-polar lipids lead to a very high electrical ... membrane Rmem is the specific membrane resistance A is the area This high resistivity prevents ions from crossing the bilayer ... Larger molecules and blood cells require adequate space between cells or holes in the lining. The high resistivity of a ... through gaps between the cells or directly through the cells. Molecules diffuse through the capillary walls due to ...
Leaf cells of higher plants contain many chloroplasts, each approximately the size of the one in some algal cells. When thin ... Chief among these are the intricate internal membranes ... have one chloroplast that occupies more than half the cell ... The chloroplast is enclosed in a double outer membrane, and its size approximates a spheroid about 2,500 nm thick and 5,000 nm ... This lipid bilayer is an essential feature of all biological membranes (see cell: The cell membrane). The hydrophobic parts of ...
Lipid Bilayers[edit]. The lipids in the lipid bilayers of cell membranes are mainly phospholipids. When mixed with water, ... of the fatty acyl groups aggregating by hydrophobic interactions. ... Cell Membrane Structure[edit]. The plasmalemma, or plasma ... Some of the proteins are associated with the surface, while others extend across the lipid bilayer. Eukaryotic cell membrane ... Within a eukaryotic cell, there are also other membranes that separate its various compartments. ...
Homeostasis Selectively Permeable Fatty acid tail Hydrophilic Hydrophobic Slideshow... ... The structure of the plasma membrane How the plasma membrane functions as a semi-permeable membrane. Vocabulary. ... The plasma membrane. Maintaining control of the internal environment. You will learn. ... membranes and cell transport. all cells are surrounded by a plasma membrane. cell membranes are composed of a lipid bilayer ...
... gla residues are needed in calcium binding and in exposing hydrophobic membrane binding regions to the cell bilayer. Lack of ... a cell-associated tissue factor becomes exposed and initiates a series of enzymatic reactions localized on a membrane surface ... partly govern the activation and binding of circulating blood-clotting enzymes and zymogens to this exposed cell membrane ... generally provided by cells and accumulating platelets. Gla residues ...
Lipid bilayer membranes are common to all living cells. - Stock Image G460/0160 ... Each phospholipid consists of a phosphate group head (blue) and a fatty acid tail (white). The tails are hydrophobic and so ... Computer model of a lipid bilayer plasma membrane. The membrane consists of a dual layer of phospholipids. ... The oily core means that only small hydrophobic solutes can pass through it. Other ions and molecules are transported through ...
The lipid bilayers present in cell membranes are selectively permeable. It allows the diffusion of some substances such as ... hydrophobic molecules, gases, and small uncharged polar molecules. However, it does not allow the diffusion of ions, charged ... What is a chromosome? How many chromosomes are in a human cell? What is the approximate number of genes in a hu.... Chemistry ... Water diffusion occurs due to differences in solute concentration across the lipid bilayer. However, ions do not easily diffuse ...
Both electrostatic and hydrophobic interactions may be involved in the association of protein C with the cell membrane. In this ... Protein C may also directly interact with fatty acid side chains within the membrane bilayer (Smirnov et al. [1999] ... "alpha4beta1 and alpha5beta1 control cell migration on fibronectin by differentially regulating cell speed and motile cell ... 262[5]:2199-2205). For example, protein C has a C-terminal 4-carboxyglutamic acid (Gla) domain which binds to the cell membrane ...
5. What do hydrophilic and hydrophobic mean and what parts of the phospolipid bilayer is which?. 6. Do fibrous proteins span ... 2. Cell membranes consist of a double layer of what?. 3. Name the types of molecules in the cell membrane and the three ... What do animal membranes have that plant membranes do not?. Identify and build your own cell membrane using the website. ... Construction of the Cell Membrane Worksheet. Directions: Use the website Construction of the Cell Membrane (http://www.wisc- ...
... plasma membrane interactions with the cytoskeleton and cell wall. Annu. Rev. Cell Dev. Biol. 13, 697-743. ... Hydrophobic interactions with the aqueous solution are important for maintaining the integrity of the lipid bilayer. With no ... If the rhizoid cell is ablated but fragments of rhizoid cell wall material remain attached to the apical cell, apical cell ... J Cell Biol 152, 531-544.. Berger, F., Taylor, A., and Brownlee, C. (1994). Cell fate determination by the cell wall in early ...
Simple diffusion of hydrophobic (non-polar) and small polar molecules through the phospholipid bilayer. ... The cell membrane (or plasma membrane) is the thin outer layer of the cell that differentiates the cell from its environment. ... Cell membranes of nerve cells, muscle cells, and some eggs are excitable electrically. In nerve cells, for example, the plasma ... Other functions of cell membranes. *Organization. Some receptors on the external surface of the cell membrane participate in ...
Active Transport across Membranes Requires Energy - 6.4 Recap - Learning Outcomes - Page 125 3 including work step by step ... It is embedded in the hydrophobic bilayer by its coating of non-polar groups. The integral protein alters its shape when a ... Biological Membranes Are Lipid-Protein Bilayers - 6.1 Recap - Learning Outcomes * 6.2 - The Cell Membrane Is Important in Cell ... Chapter 5 - Cells: The Working Units of Life * Chapter 6 - Cell Membranes * 6.1 - ...
And this is very, very important biochemical feature of cell membrane.. Only small-sized hydrophobic molecules can, so ... can passively and nicely diffuse across a phospholipid bilayer.. ... cellular membrane is keeping our cells safe and. allowing ... can be transported inside this intestinal epithelial cells.. And then on the other side, this is like a Base membrane structure ... into the epithelial cells, intestine epithelial cells, and that transport,. monosaccharide transport, is mediated by this ...
Ch.5 Notes Cell membranes isolate cell contents whole allowing communication with the environment Functions Isolate cells ... Polar and water soluble biological molecules cannot pass through the nonpolar hydrophobic fatty acid tails of bilayer Animals- ... Anchor cell membranes. Span plasma membrane-linking cytoskeleton inside cell with extracellular matrix outside, anchoring cell ... Cell membranes isolate cell contents whole allowing communication with the environment Functions Isolate cells contents from ...
This structure shields tail-anchored membrane proteins -- which have roles in a wide variety of cellular functions from ... from harmful aggregation or misfolding as they move through the inner environment of a cell. The findings clarify the mechanism ... The molecular complex that guides an important class of proteins to correct locations in cell membranes does so by forming a ... These proteins contain hydrophobic regions that allow them to be embedded in the hydrophobic lipid bilayer of cell membranes. ...
... meaning that they cannot touch the Hydrophobic interior of the lipid bilayer. Faciliated Diffusion. 1. 2. 3. 4. 5. 6. 7. 8. 9. ... Process used for molecules that cant seperate cell membranes on command.. 2. The part of the cell membrane that the carrier ... What Are The Steps to Facilitated Diffusion? 1. A molecule bonds to a carrier protein* on one side of the cell membrane. 2. The ... Cell Membrane Passive or Active Transport? Facilitated Diffusion uses passive transport. Facilitated Diffusion in Action http ...
... cell: Membrane lipids: …each forming half of a bilayered wall. A bilayer is composed of two sheets of phospholipid molecules ... and one or more hydrophobic "tails." In a water medium, the molecules form a lipid bilayer, or two-layered sheet, in which the ... In cell: Membrane lipids. …each forming half of a bilayered wall. A bilayer is composed of two sheets of phospholipid molecules ... lipid bilayer; cell membranePhospholipid molecules, like molecules of many lipids, are composed of a hydrophilic "head" ...
"A major component of a cell membrane is: phospholipid, a fluid bilayer consisting of the hydrophobic and hydrophilic..." ...
This tutorial introduces cell membranes. Other sections include plants, animal systems, invertebrates, vertebrates, and ... The two surfaces of molecules create the lipid bilayer. Ingrained in the Membrane. What about the membrane proteins? Scientists ... The head section of the molecule likes water (hydrophilic) while the tail does not (hydrophobic). Because the tails want to ... Cell Membranes. According to cell theory, cells are the main unit of organization in biology. Whether you are a single cell or ...
  • however, the cell wall plays mostly a mechanical support role rather than a role as a selective boundary [ citation needed ] . (thefullwiki.org)
  • In fungi , bacteria , and plants an additional cell wall forms the outermost boundary, however, the cell wall plays mostly a mechanical support role rather than a role as a selective boundary. (wikidoc.org)
  • The bilayer is highly selective about what it lets through, as its primary function is as a protective barrier for the cell. (everything2.com)
  • The cell wall has pores that allow materials to enter and leave the cell, but they are not very selective about what passes through. (fsu.edu)
  • Indeed, lipids have commonly been considered a mere support for the transient or permanent association of membrane proteins, while acting as a selective cell/organelle barrier. (nih.gov)