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Biological Membranes quiz #1

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  • What is the fluid mosaic model of biological membranes, and what are its key features?
    The fluid mosaic model describes biological membranes as dynamic structures composed of a lipid bilayer with embedded proteins. The lipids and proteins can move laterally within the membrane, giving it fluidity, while the diverse proteins create a mosaic-like appearance.
  • Which types of lipids are most suitable for forming stable lipid bilayers in biological membranes, and why?
    Free phospholipids, such as glycerophospholipids and sphingophospholipids, are most suitable for forming stable lipid bilayers because their square-shaped geometry allows them to pack tightly without gaps, creating a stable bilayer structure.
  • How can the composition of biological membranes vary between different cells and organelles?
    The composition of biological membranes can vary significantly between different cells and organelles, with differences in both the types of phospholipids and the proportion of embedded proteins. Protein content can range from 20% to 80% by mass, and the lipid and protein makeup can differ between the extracellular and intracellular leaflets, as well as among various organelles.
  • What is the fluid mosaic model of biological membranes?
    The fluid mosaic model describes biological membranes as dynamic lipid bilayers with embedded proteins that can move laterally, giving the membrane both fluidity and a mosaic-like appearance.
  • Which types of lipids are most suitable for forming stable lipid bilayers in biological membranes, and why?
    Free phospholipids, such as glycerophospholipids and sphingophospholipids, are most suitable because their square-shaped geometry allows them to pack tightly without gaps, creating a stable bilayer.
  • How can the composition of biological membranes vary between different cells and organelles?
    The composition can vary significantly, with differences in both the types of phospholipids and the proportion of embedded proteins, and protein content can range from 20% to 80% by mass.
  • What is the main structural difference between a micelle and a lipid bilayer?
    A micelle is a monolayer of lipids with a hydrophobic core, while a lipid bilayer consists of two layers of lipids forming a hydrophilic exterior and interior.
  • Why are free fatty acids and triacylglycerols not suitable for forming lipid bilayers?
    Their triangular or trapezoid-shaped geometry creates gaps when packed together, making them unstable for forming bilayers or vesicles.
  • What are the two leaflets of a lipid bilayer called, and how do they differ?
    The two leaflets are called the extracellular leaflet (outside the cell) and the intracellular leaflet (inside the cell), and they can have different lipid and protein compositions.
  • What proportion of proteins can be found in biological membranes by mass?
    Biological membranes can contain anywhere from 20% to 80% proteins by mass, depending on the cell or organelle.