Cell Membrane Structure and Functions Quiz

The main force stabilizing the lipid bilayer of cell membranes is the hydrophobic interaction between the hydrophobic tails of lipids, which avoids contact with water in the surrounding environment.

The Gorter-Grindel model of the cell membrane only addressed the lipid bilayer structure, neglecting the organization of proteins.

The Danielli-Davson model proposed that proteins are adsorbed to the polar faces of the lipid bilayer and may span the membrane, forming channels.

The trilaminar appearance of membranes observed under Transmission Electron Microscopy (TEM) after staining with osmium tetroxide is due to the different affinities of the hydrophilic and hydrophobic regions of the lipid bilayer to osmium.

The thickness of cell membranes is variable, depending on the composition of fatty acids and proteins.

The fluid-mosaic model describes the cell membrane as a fluid structure where proteins are embedded in a lipid bilayer, creating a mosaic-like appearance.

The fluid-mosaic model combines the understanding of both the lipid bilayer structure and protein distribution, providing a comprehensive description of cell membrane organization.

The fluid-mosaic model implies that membranes are dynamic and constantly in motion, allowing for flexibility and adaptation to various cellular functions.

A model describing the structure of cell membranes, where phospholipids form a bilayer with proteins embedded within, resembling a mosaic.

A type of protein that is loosely attached to the surface of the cell membrane, either on the inner or outer side.

A type of protein that is tightly bound to the cell membrane, often connected through a lipid molecule.

A type of integral protein that spans the entire cell membrane, passing through both layers.

A type of integral protein that only passes through one layer of the cell membrane.

A specific stretch of amino acids in integral proteins that is composed of hydrophobic residues. This region helps the protein anchor itself within the hydrophobic core of the membrane.

A type of integral membrane protein that binds to a specific molecule, such as a hormone, and initiates a signal transduction pathway within the cell.

A type of protein that associates with other proteins or cytoskeletal components, helping to maintain the structure and function of the cell membrane.

The unequal distribution of proteins, lipids, and carbohydrates between the inner and outer leaflets of a cell membrane.

Proteins that help transport lipids from one leaflet of the cell membrane to the other, maintaining membrane asymmetry.

Proteins that interact with the extracellular matrix, located on the outer leaflet of the cell membrane.

Proteins that interact with the cytoskeleton, located on the inner leaflet of the cell membrane.

The unequal distribution of lipids between the inner and outer leaflets of a cell membrane.

The presence of carbohydrate motifs always directed towards the exterior side of the plasma membrane.

The property of cell membranes to be flexible and dynamic, allowing for movement of lipids and proteins within the membrane.

Factors like temperature, lipid composition, and cholesterol content affect the fluidity of cell membranes.

Specialized junctions between neurons and other cells (e.g., muscle fibers, gland cells, nerve cells). They involve recognition between presynaptic and postsynaptic membranes facilitated by cadherins.

A narrow space (20-50 nm) between the presynaptic and postsynaptic membranes at a synaptic junction. Neurotransmitters diffuse across this gap to transmit signals.

Chemical messengers released from the presynaptic neuron at a synaptic junction. Examples include acetylcholine.

Integral membrane proteins on the postsynaptic membrane that bind neurotransmitters, initiating a signal.

Clusters of pipeline-like structures between neighboring cells, allowing the exchange of molecules and solutes.

Integral proteins that form the gap junctions and facilitate the passage of molecules.

Clusters of six connexin subunits that form the core of a gap junction channel.

A movement of the esophagus that occurs due to coordinated contractions of smooth muscle facilitated by gap junctions, enabling swallowing.

A hybrid cell formed by the fusion of two cells from different species, often containing distinct markers for identification.

A technique used to track the movement of molecules within a cell membrane by selectively irradiating a region and observing the recovery of fluorescence.

The ability of molecules, like proteins and lipids, to move laterally within the plane of a cell membrane.

The structural network within a cell that provides support and helps organize the movement of molecules and organelles.

Specialized cell structures that are anchored to the cytoskeleton, influencing the movement of transmembrane proteins.

The process where specialized cells, like epithelial cells, have distinct membrane regions with different functions and protein composition.

The interaction between the cell's internal cytoskeleton and the extracellular matrix, affecting the mobility of membrane proteins.

A specialized cell junction found in animal cells, formed by the close apposition of plasma membranes from adjacent cells, allowing the passage of small molecules and ions.

Connexons are protein channels that form gap junctions. Each connexon is composed of six connexin proteins. The arrangement of these proteins allows small molecules to pass between cells.

The passage of molecules through gap junctions is not selective. This means that small molecules such as amino acids and sugars can pass through easily. However, the passage of larger molecules is restricted.

The opening and closing of gap junctions is regulated by various factors. For example, a decrease in pH or an increase in calcium concentration can cause the gap junction to close.

A rigid structure that surrounds plant cells, composed primarily of cellulose and a matrix of hemicellulose, pectin, and glycoproteins.

Plasmodesmata are channels that connect the cytoplasm of adjacent plant cells, facilitating the exchange of molecules and communication between cells.

The cell wall is interrupted at the location of plasmodesmata, allowing the plasma membranes of adjacent cells to connect.

A membranous structure found in the center of a plasmodesma, derived from the smooth endoplasmic reticulum (SER), which may help regulate the passage of molecules.