Plasma Membrane 1
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Plasma Membrane 1

This quiz covers the functions and properties of biological membranes, components of cell membranes, types of cell membrane proteins and their roles, composition and structure of membrane lipids, visualization techniques, and major cell membrane phospholipids. It is part of a Cellular Biology & Homeostasis course.

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@VerifiableSlideWhistle

Questions and Answers

Which technique is necessary to study the details of the organization of cell membranes?

X-ray diffraction

According to the fluid mosaic model, cell membranes are described as:

Fluid, dynamic structures with molecules able to move in the plane of the membrane

What is the typical thickness of a plasma membrane as viewed in cross-section?

5-8 nm

In an electron micrograph of an E.coli cell, what is denoted by the red circle in the schematic of the lipid bilayer?

<p>Hydrophilic head with a polar phosphoglycerol group</p> Signup and view all the answers

Which type of structures exclude water as well as polar or charged compounds?

<p>Hydrophobic barriers</p> Signup and view all the answers

What is the main characteristic shared by all cell membranes when viewed in cross-section?

<p>Trilaminar appearance</p> Signup and view all the answers

What is the main function of cell membranes?

<p>Regulate movement of materials into and out of the cell</p> Signup and view all the answers

Which statement best describes the structure of a cell membrane?

<p>Selectively permeable to polar solutes</p> Signup and view all the answers

What is the significance of the cell membrane in cell-to-cell communication?

<p>Facilitates electrical signaling between cells</p> Signup and view all the answers

Which function is NOT attributed to cell membranes?

<p>Producing genetic mutations</p> Signup and view all the answers

Why are cell membranes described as 'selectively permeable'?

<p>They regulate which molecules can pass based on size and polarity</p> Signup and view all the answers

In what way do cell membranes contribute to compartmentalization in eukaryotic cells?

<p>Help separate processes and compartments within the cell</p> Signup and view all the answers

What is the main function of compartmentalization in cell membranes?

<p>Separate anabolic and catabolic processes</p> Signup and view all the answers

Which organelles are involved in fatty acid oxidation for energy production?

<p>Mitochondria</p> Signup and view all the answers

What is the main role of proteins in cell membranes?

<p>Facilitate transport across the membrane</p> Signup and view all the answers

Which component makes up about 50% of the mass of most animal cell membranes?

<p>Lipids</p> Signup and view all the answers

Where are the TCA cycle and electron transport chain located in a cell?

<p>Mitochondria</p> Signup and view all the answers

Which type of cations are commonly found associated with cell membranes?

<p>$Ca^{2+}$ and $Mg^{2+}$</p> Signup and view all the answers

What is the main difference between prokaryotic and eukaryotic plasma membranes?

<p>Eukaryotic membranes are composed of different types of phospholipids, while prokaryotic membranes are composed of a single type.</p> Signup and view all the answers

What role do sterols like cholesterol play in the stability and fluidity of cell membranes?

<p>Increase both mechanical stability and fluidity.</p> Signup and view all the answers

What is the purpose of membrane fusion in cellular processes?

<p>To allow for the transport of material between organelles and the plasma membrane.</p> Signup and view all the answers

How do lipid molecules assemble in aqueous environments?

<p>With hydrophobic tails in the interior and hydrophilic heads outside to water.</p> Signup and view all the answers

What is the significance of membrane fission in cellular processes?

<p>To enable the splitting of a membrane into two parts for transport purposes.</p> Signup and view all the answers

How do hydrophilic molecules behave in aqueous environments?

<p>They dissolve readily in water due to uncharged polar groups that interact favorably with water molecules.</p> Signup and view all the answers

Why does phospholipid bilayer closure to form a sealed compartment represent an energetically favorable process?

<p>The closed structure prevents the exposure of hydrophobic tails to water, which is energetically unfavorable.</p> Signup and view all the answers

In an aqueous environment, which type of molecules form micelles according to the text?

<p>Fatty acids</p> Signup and view all the answers

What is the main difference between vesicles and liposomes as outlined in the text?

<p>Vesicles are naturally occurring, while liposomes are artificial structures created in laboratories.</p> Signup and view all the answers

What is the function of vesicles within cells as described in the text?

<p>Metabolism</p> Signup and view all the answers

Which technique directly produces a three-dimensional image of the surface of a specimen according to the text?

<p>Scanning electron microscopy (SEM)</p> Signup and view all the answers

Why do phospholipids form bilayers or liposomes according to the text?

<p>Their cylinder-shaped form leads to bilayer or liposome formation.</p> Signup and view all the answers

What is the main function of the cell membrane in facilitating electrical signaling between cells?

<p>Serving as an attachment surface</p> Signup and view all the answers

Which type of cells break and re-seal their cell membranes for fusion or fission?

<p>Eukaryotic cells</p> Signup and view all the answers

How do cell membranes contribute to the regulation of molecular traffic across the boundary?

<p>By being selectively permeable</p> Signup and view all the answers

What is the primary role of the lipid bilayer structure in the cell membrane?

<p>Providing a barrier to separate cellular compartments</p> Signup and view all the answers

Which visualization technique is commonly used to study the details of the organization of cell membranes?

<p>Electron microscopy</p> Signup and view all the answers

What is the significance of the compartmentalization provided by cell membranes in eukaryotic cells?

<p>Segregating processes and compartments</p> Signup and view all the answers

What type of structures are cell membranes, as described in the text?

<p>Fluid and dynamic</p> Signup and view all the answers

Which component makes up the central region in the trilaminar appearance of cell membranes when viewed in cross-section?

<p>Hydrophilic heads</p> Signup and view all the answers

What does the red circle in the schematic of the lipid bilayer denote?

<p>Hydrophilic head</p> Signup and view all the answers

Why is membrane thickness important in influencing the rate of diffusion across cell membranes?

<p>Thinner membranes allow for faster diffusion.</p> Signup and view all the answers

What characteristic appearance do all cell membranes share when viewed in cross-section?

<p>Trilaminar appearance</p> Signup and view all the answers

Which technique is necessary to study the details of the organization of cell membranes as implied in the text?

<p>Freezefracture</p> Signup and view all the answers

Why does the spontaneous closure of a phospholipid bilayer to form a sealed compartment represent an energetically favorable process?

<p>It prevents the exposure of the hydrophobic hydrocarbon tails to water, which is energetically unfavorable.</p> Signup and view all the answers

Which type of molecules form micelles in an aqueous environment according to the text?

<p>Amphipathic molecules</p> Signup and view all the answers

What is the main difference between vesicles and liposomes?

<p>Vesicles consist of liquid enclosed by a lipid bilayer, while liposomes consist of cytoplasm enclosed by a lipid bilayer.</p> Signup and view all the answers

What is the role of lipids in forming vesicles and bilayers?

<p>Lipids spontaneously form vesicles and bilayers due to their amphipathic nature.</p> Signup and view all the answers

What is the significance of vesicles in cellular processes?

<p>Vesicles are involved in temporary storage, transport, and metabolic processes within cells.</p> Signup and view all the answers

How do liposomes differ from vesicles?

<p>Liposomes consist of liquid enclosed by a lipid bilayer, while vesicles consist of cytoplasm enclosed by a lipid bilayer.</p> Signup and view all the answers

What does the freeze-fracture technique involve?

<p>Breaking apart a frozen biological sample to study the membrane</p> Signup and view all the answers

How do differences in the length and saturation of fatty acid tails affect phospholipid molecules?

<p>Enhance the ability to pack together and influence membrane fluidity</p> Signup and view all the answers

What is the main structural difference between saturated and unsaturated fatty acids in cell membranes?

<p>The presence of double bonds in unsaturated fatty acids</p> Signup and view all the answers

Which major phospholipids predominate in the plasma membrane of many mammalian cells?

<p>Phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, sphingomyelin</p> Signup and view all the answers

Why is the freeze-fracture technique important for studying cell membranes?

<p>It reveals internal membrane organization by fracturing frozen samples</p> Signup and view all the answers

How does the freeze-etch electron microscopy technique differ from freeze-fracture?

<p>It creates a 3D view of surfaces inside cells by etching frozen samples</p> Signup and view all the answers

What is the main purpose of compartmentalization in cell membranes?

<p>Avoiding interference in reactions</p> Signup and view all the answers

Where are fatty acid oxidation for energy production and fatty acid synthesis held to avoid competition?

<p>Mitochondria and ER</p> Signup and view all the answers

Which component makes up approximately 50% of the mass of most animal cell membranes?

<p>Lipids</p> Signup and view all the answers

Where are the TCA cycle and electron transport chain located to ensure energy efficiency?

<p>Mitochondria</p> Signup and view all the answers

How do cell membranes contribute to cell-to-cell communication?

<p>By facilitating the exchange of signaling molecules</p> Signup and view all the answers

What is the significance of proteins in biological membranes?

<p>To interact with other molecules and transport materials</p> Signup and view all the answers

What type of model describes cell membranes as fluid, dynamic structures where most molecules can move?

<p>Fluid mosaic model</p> Signup and view all the answers

In the trilaminar appearance of all cell membranes, what do the two electron-dense layers consist of?

<p>Proteins</p> Signup and view all the answers

What is the main function of the hydrophilic head denoted by the red circle in the schematic of the lipid bilayer?

<p>Attract water and charged compounds</p> Signup and view all the answers

What is the significance of the less dense central region in the trilaminar appearance of cell membranes?

<p>Facilitates movement of transmembrane proteins</p> Signup and view all the answers

What technique is necessary to study the detailed organization of cell membranes and involves breaking them to reveal their inner structures?

<p>Freezefracture</p> Signup and view all the answers

In what way does membrane thickness influence the rate of diffusion across cell membranes?

<p>Thicker membranes impede diffusion</p> Signup and view all the answers

What is the main function of the plasma membrane in a cell according to the text?

<p>Facilitating electrical signaling between cells</p> Signup and view all the answers

Why are cell membranes described as 'selectively permeable'?

<p>To only permit certain molecules to cross while blocking others</p> Signup and view all the answers

Which component plays a central role in defining the external boundaries of a cell?

<p>Membrane lipids</p> Signup and view all the answers

How do cell membranes contribute to biological energy conservation?

<p>By facilitating electron transport chain reactions</p> Signup and view all the answers

What is a key feature of the lipid bilayer structure in cell membranes?

<p>Providing flexibility and selective permeability</p> Signup and view all the answers

Which major function of cell membranes involves serving as an attachment surface for extracellular structures?

<p>Providing attachment points for cytoskeleton proteins</p> Signup and view all the answers

Why is the closure of a phospholipid bilayer to form a sealed compartment energetically favorable?

<p>It stabilizes the closed structure by avoiding exposure of hydrophobic tails to water.</p> Signup and view all the answers

What is the main difference between micelles and bilayers according to the text?

<p>Micelles are cone-shaped, while bilayers are cylinder-shaped.</p> Signup and view all the answers

In cell membranes, what provides the self-healing property to the bilayer?

<p>Free edges</p> Signup and view all the answers

What is the purpose of vesicles within cells as described in the text?

<p>To have cytoplasm with different composition from the cytosol</p> Signup and view all the answers

How do liposomes differ from vesicles according to the text?

<p>Liposomes consist of liquid/cytoplasm enclosed by a lipid bilayer, while vesicles are intra or extra cellular structures.</p> Signup and view all the answers

What is the main function of lipids in forming vesicles and bilayers?

<p>To provide stability and enclosure</p> Signup and view all the answers

What is the main function of transmembrane proteins in cell membranes?

<p>Serve as structural links between the cytoskeleton and the extracellular matrix</p> Signup and view all the answers

Which statement accurately describes the lipid bilayer in cell membranes?

<p>Consists of amphipathic lipid molecules</p> Signup and view all the answers

What is the significance of membrane proteins in drug development?

<p>They serve as targets for over 50% of modern medicinal drugs</p> Signup and view all the answers

Which lipid molecule is the most abundant in cell membranes?

<p>Phospholipids</p> Signup and view all the answers

What is the primary reason for the bilayer structure of cell membranes?

<p>Due to special properties of lipids that cause spontaneous assemblage into bilayers</p> Signup and view all the answers

Why are over 30% of human genome's proteins classified as membrane proteins?

<p>To facilitate signal transduction and proper cell function</p> Signup and view all the answers

How does the freeze-fracture technique help in studying cell membranes?

<p>It physically breaks apart frozen biological samples to expose structural detail</p> Signup and view all the answers

What is the function of the polar head group in phospholipids?

<p>To anchor the phospholipid in the membrane</p> Signup and view all the answers

How do differences in the length and saturation of fatty acid tails affect membrane fluidity?

<p>They affect the ability of phospholipid molecules to pack together and guarantee membrane fluidity</p> Signup and view all the answers

What is the significance of coating the fractured surface with a metal layer in freeze-fracture electron microscopy?

<p>To provide contrast for electron microscopy</p> Signup and view all the answers

What makes up more than half of the lipid mass in most cell membranes?

<p>Phospholipids</p> Signup and view all the answers

What role do unsaturated fatty acids play in phospholipids compared to saturated fatty acids?

<p>Create small kinks in the fatty acid tails</p> Signup and view all the answers

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