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Lipids: Structure and Function in General Biology

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Termini in questo insieme (20)

  • Why are lipids not considered true polymers?
    Lipids are not made from repeating monomer units and do not form long chains of repeating subunits, unlike proteins or nucleic acids.
  • What makes lipids hydrophobic?
    Lipids have mostly nonpolar hydrocarbon chains that form nonpolar covalent bonds, causing them to repel water.
  • What are the three main types of biologically important lipids?
    Fats (energy storage), phospholipids (cell membranes), and steroids (hormones and structural molecules).
  • What two smaller molecules compose a fat?
    A fat is built from glycerol (a three-carbon alcohol) and fatty acids joined by dehydration reactions.
  • What is the structure of a fatty acid?
    A fatty acid has a carboxyl group (-COOH) at one end and a long hydrocarbon chain (16-18 carbons) that is mostly nonpolar.
  • How is a fat (triacylglycerol) formed?
    Three fatty acids are attached to one glycerol molecule by ester linkages through dehydration reactions.
  • What is the difference between saturated and unsaturated fatty acids?
    Saturated fatty acids have no double bonds and pack tightly, solid at room temperature; unsaturated fatty acids have one or more cis double bonds causing kinks, making them liquid.
  • Why are unsaturated fats liquid at room temperature?
    The cis double bonds create kinks in the hydrocarbon chains, preventing tight packing and keeping them liquid.
  • What health implications are associated with saturated fats?
    High intake of saturated fats may lead to cardiovascular disease due to plaque deposits in arteries.
  • What is the primary function of fats in animals?
    Fats serve as long-term energy storage, cushion vital organs, and provide insulation.
  • What are adipose cells?
    Specialized cells that store fat, swelling or shrinking as fat is added or used.
  • What is the structure of a phospholipid?
    A phospholipid consists of two fatty acid tails (hydrophobic), a phosphate group (hydrophilic), and a glycerol backbone.
  • What does amphipathic mean in phospholipids?
    Phospholipids have both hydrophobic tails and a hydrophilic head, allowing them to form bilayers in water.
  • How do phospholipids arrange themselves in water?
    They self-assemble into a bilayer with hydrophilic heads facing water and hydrophobic tails shielded inside.
  • What is the biological importance of phospholipids?
    They are the major component of cell membranes, essential for compartmentalization, membrane fluidity, and selective permeability.
  • What are steroids and their structure?
    Steroids are lipids with four fused carbon rings and different functional groups, including cholesterol and hormones.
  • What role does cholesterol play in cells?
    Cholesterol is a component of animal cell membranes and affects membrane fluidity and stability.
  • How do saturated and trans fats affect health?
    Both can raise cholesterol levels and contribute to cardiovascular disease.
  • What is an ester linkage in fats?
    A bond formed between glycerol and fatty acids by dehydration, linking the molecules in a fat.
  • What causes the kink in unsaturated fatty acid chains?
    The cis double bond causes bending, preventing tight packing of the chains.