BIOCHEM_S1T4_MEMBRANES-STRUCTURE-AND-FUNCTIONS

An electrochemical disturbance propagates in a wave-like form, generating a nerve impulse.

They allow for variation in lipid content, incorporation of purified membrane proteins, controlled environments, and entrapment of compounds like drugs and genes.

By maintaining an asymmetry of inside-outside voltage and using voltage-gated channels.

Micelles, where hydrophobic regions are shielded from water and hydrophilic polar groups are immersed in the aqueous environment.

Through the GLUT4 transporter, which is enhanced by insulin.

Asymmetric with distinct inner and outer surfaces or leaflets.

The movement of proteins within the membrane; many nonmobile proteins do not exhibit this due to being anchored to the cytoskeleton.

Specific proteins involved in facilitated diffusion and active transport.

The process involved in generating second messenger signaling molecules like cyclic nucleotides and calcium.

They can lead to diseases by altering the function of receptors, transporters, ion channels, and enzymes.

They contain gap junctions that allow adjacent cells to communicate by exchanging materials.

The passive transport of a solute from a higher to a lower concentration mediated by a specific protein transporter.

A model proposed by Singer and Nicolson in 1972, describing membranes as having phospholipids that undergo rapid lateral diffusion and are influenced by lipid composition.

The process by which cells take up large molecules.

A phospholipid formed from sphingosine and a fatty acid, esterified to phosphorylcholine.

The process of releasing macromolecules to the exterior of the cell.

Molecules that act as membrane shuttles for various ions, such as valinomycin for K+.

1/3, distributed between plasma and interstitial compartment.

Phospholipids, glycosphingolipids, and cholesterol.

They readily diffuse through the hydrophobic regions of the membrane due to their small size and low interaction with solvents.

Ingestion of large particles such as viruses, bacteria, or cellular debris, occurring in specialized cells like macrophages.

Proteins that form water channels in certain membranes.

Structures that allow direct transfer of small molecules between neighboring cells, composed of connexins.

Fat maldigestion.

It regulates intracellular concentrations of Na+ and K+, maintaining low Na+ and high K+ concentrations.

Na+, Ca2+, Cl−, K+, Mg2+, and phosphate.

It regulates intracellular concentrations of sodium and potassium, requiring energy for active transport.

Cholesterol.

No, it is absent in plant cells.

Symport moves two solutes in the same direction, while antiport moves two molecules in opposite directions.

They use the gradient of one substrate created by active transport to drive the movement of another substrate.

It pumps three Na+ out and two K+ into cells.

Approximately 30%.

Elevated levels of chloride in sweat (>60 mmol/L).

Lipids, proteins, and carbohydrate-containing molecules.

It minimizes the hydrophilic character of peptide bonds, allowing them to be amphipathic and form integral parts of the membrane.

Caveolae derive from lipid rafts and contain the protein caveolin-1, which may be involved in their formation.

A transport system that moves one type of molecule bidirectionally.

They increase the number of kinks, making the membrane more fluid.

Channels that open in response to a specific molecule binding to a receptor.

1. Overall structures, 2. Rapid ion conduction, 3. Selectivity, 4. Gating properties.

They span as a bundle of α-helical transmembrane segments, are amphipathic and globular, and are asymmetrically distributed in the membrane bilayer.

2/3.

Vectorial movement of a solute across a membrane against a concentration gradient, requiring energy.

They function as enzymes, pumps, transporters, channels, structural components, antigens, and receptors.

A process of cellular uptake of fluid and its contents, also known as 'cell drinking'.

Viruses like hepatitis, poliomyelitis, AIDS, and COVID-19 can enter cells via this mechanism.

The hydrophobic end binds to hydrophobic regions, displacing bound lipids.

They likely play a role in endocytosis (cellular uptake of various components).

Simple diffusion and facilitated diffusion.

Vesicles surrounded by a lipid bilayer with an aqueous interior, formed through mild sonication.

It describes membranes as dynamic structures with lipid rafts, caveolae, and tight junctions.

Concentration gradient, electrical potential, permeability coefficient, hydrostatic pressure gradient, and temperature.

Specialized areas of the exoplasmic leaflet of the lipid bilayer enriched in cholesterol, sphingolipids, and certain proteins.

Through transport from the ER in vesicles, direct contact between membranes, or via phospholipid exchange proteins.

Energy, usually in the form of ATP, as it occurs against an electrical or chemical gradient.

They have selective permeabilities, act as barriers, and facilitate exchanges with the extracellular environment through exocytosis and endocytosis.

They compartmentalize the body's internal water and regulate ionic compositions of fluids.

The hydrophobic effect, which describes the tendency of nonpolar molecules to self-associate in an aqueous environment.

Energy (usually from ATP hydrolysis), Ca2+, and cytoskeletal elements.

Through endocytosis and exocytosis mechanisms.

Sugar-containing lipids built on a ceramide backbone.

The transfer of one solute depends on the simultaneous or sequential transfer of another solute.

They solubilize and purify membrane proteins.

Mechanical stimuli such as pressure and touch.

Fat maldigestion, infertility in males due to abnormal development of the vas deferens, and elevated levels of chloride in sweat (>60 mmol/L).

The passive flow of a solute from a higher to a lower concentration due to random thermal movement.

Bidirectional delivery system, brings nutrients, O2, ions, hormones, and removes waste products.

They allow the selective entry of various ions across the membrane.

Phosphatidylcholine.

They transfer certain phospholipids from the inner to the outer leaflet of the membrane.

They contain both hydrophobic and hydrophilic regions.

Lipid bilayer-enclosed structures that can include exosomes and microvesicles, delivering distinct 'payloads' to target cells.

They prevent the diffusion of macromolecules between cells.

Peripheral proteins do not interact directly with the hydrophobic cores of phospholipids and are bound to the hydrophilic regions of integral proteins and phospholipid head groups.

They provide electrical insulation and speed up the propagation of the nerve impulse.

Thermal agitation of the molecule, concentration gradient, and solubility of the solute.

Cholesterol buffers membrane fluidity by increasing fluidity below Tm and limiting disorder above Tm.

Fluid-phase pinocytosis (nonselective) and absorptive pinocytosis (receptor-mediated).

Integral proteins interact extensively with phospholipids and require detergents for solubilization, while peripheral proteins do not.

By facilitated diffusion or active transport.

Facilitated diffusion can be saturated and involves specific transporters.

Size, extent of hydration, and charge density of the ion.

An integral membrane protein composed of four identical subunits with two trans-membrane segments, creating an inverted 'V' structure.

They form water channels that facilitate the movement of water across certain membranes.

Infertility due to abnormal development of the vas deferens.

It is crucial for maintaining a net negative electrical potential inside the cell.

The temperature at which membrane structure transitions from an ordered to a disordered state.

They fuse with primary lysosomes to form secondary lysosomes for intracellular disposal.

Cystic fibrosis.

They face the aqueous environment.

A recessive genetic disorder caused by mutations in the CFTR gene, leading to chronic bacterial infections.

Transmembrane proteins that allow the selective entry of various ions.

It allows glucose to enter cells by binding with Na+, which moves down its electrochemical gradient.

ATP hydrolysis.

In the cell membrane.

They can remain as membrane proteins, become part of the extracellular matrix, or enter extracellular fluid to signal other cells.

The transmembrane gradient of the substrate.

Changes in membrane potential.

Saturated fatty acids form straight tails, while unsaturated fatty acids form kinked tails.

Micelles.