Biology Chapter on Cell Membranes
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Questions and Answers

Which condition is associated with increased levels of serum LDL?

  • Hepatic jaundice
  • Hemolytic jaundice
  • Malabsorption syndrome
  • Obstructive jaundice (correct)
  • Which type of lipoprotein is associated with a high incidence of coronary atherosclerosis?

  • LDL (correct)
  • IDL
  • VLDL
  • HDL
  • Which lipoprotein is inversely related to the incidence of coronary atherosclerosis?

  • IDL
  • VLDL
  • LDL
  • HDL (correct)
  • What is the primary biochemical defect in homozygotes with familial hypercholesterolemia?

    <p>Functional deficiency of plasma membrane receptors for LDL</p> Signup and view all the answers

    In which condition is the biochemical defect primarily related to Apo-B synthesis?

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

    Familial hypertriacylglycerolemia is primarily associated with which condition?

    <p>Overproduction of VLDL</p> Signup and view all the answers

    Prostaglandins synthesized from essential fatty acids contain how many carbon atoms?

    <p>20 carbon atoms</p> Signup and view all the answers

    Active prostaglandins possess at least one double bond between which carbon positions?

    <p>13 and 14</p> Signup and view all the answers

    What is the normal range of plasma total phospholipids?

    <p>1.8–5.8 mmol/L</p> Signup and view all the answers

    What is the density range of HDL2?

    <p>1.032–1.063</p> Signup and view all the answers

    Study Notes

    Phospholipids and Cell Membrane

    • Phospholipids are essential components of cell membranes due to their dual nature, featuring both polar and nonpolar groups.
    • This unique structure allows them to form bilayers, critical for membrane integrity and function.

    Neutral Fats and Unsaponifiable Matter

    • Unsaponifiable matter in neutral fats includes hydrocarbons and cholesterol, among others.
    • Triacylglycerols form the bulk of neutral fats but are saponifiable.

    Higher Alcohols in Waxes

    • The higher alcohol commonly found in waxes is cetyl alcohol.

    Gangliosides and Location

    • Gangliosides, complex glycosphingolipids, are primarily found in the brain, playing a vital role in cell signaling and recognition.

    Unsaturated Fatty Acids

    • Cod liver oil is high in the unsaturated fatty acid timnodonic acid, which contains five double bonds.

    Phospholipids as Surfactants

    • Lecithin is a phospholipid that acts as a surfactant, helping reduce surface tension in various biological processes.

    Historical Use of Oils

    • Chaulmoogric oil, which contains cyclic fatty acids, was historically used in leprosy treatment.

    Rancidity Prevention in Fats

    • Tocopherol can effectively delay or prevent rancidity by acting as an antioxidant in fats.

    Gangliosides and Sialic Acid

    • Gangliosides derived from glucosylceramide include one or more molecules of sialic acid, significant for cellular interactions.

    Drying Oils

    • Linseed oil is characterized as a 'drying oil' that readily oxidizes at room temperature, leading to a hard, waterproof finish.

    Drug Interaction and Enzyme Inhibition

    • Allopurinol is a drug that inhibits xanthine oxidase, effectively preventing uric acid synthesis.

    Insulin Crystallization

    • Zinc ions (Zn++) are essential for the crystallization and storage of the hormone insulin.

    Caloric Yield from Oxidation

    • Lipids produce the most calories upon oxidation, surpassing glucose, glycogen, or proteins.

    Vitamins and Milk Deficiency

    • Milk is notably deficient in vitamin C, vital for various metabolic processes.

    Mineral Deficiency in Milk

    • Iron is the mineral in which milk is deficient, impacting dietary iron intake.

    Prostaglandin Synthesis Inhibition

    • Aspirin inhibits the synthesis of prostaglandins, affecting inflammation and pain.

    HDL Synthesis

    • High-Density Lipoprotein (HDL) is synthesized and secreted from the liver, contributing to cholesterol transport.

    Lipoprotein Receptor-Mediated Endocytosis

    • Cholesterol esters enter cells via receptor-mediated endocytosis, primarily occurring in lysosomes.

    Membrane Lipid Bilayer Composition

    • Choline phosphoglycerides are more concentrated in the outer leaflet of the membrane lipid bilayer compared to other types.

    Membrane Dynamics

    • Transbilayer diffusion of phospholipids occurs less rapidly than flexing of fatty acyl chains, lateral diffusion, or rotation around axes.

    Cholesterol and Jaundice

    • Serum Low-Density Lipoprotein (LDL) increases in hepatic jaundice, affecting cholesterol metabolism.

    Lipoproteins and Atherosclerosis

    • LDL is associated with a high incidence of coronary atherosclerosis, while HDL inversely relates to its occurrence.

    Familial Hypercholesterolemia

    • Functional deficiency of plasma membrane LDL receptors is a primary biochemical lesion in homozygotes with familial hypercholesterolemia.

    Abetalipoproteinemia Defect

    • In abetalipoproteinemia, the defect lies in Apo-B synthesis, impairing lipoprotein formation.

    Familial Hypertriglyceridemia

    • Familial hypertriglyceridemia is linked to overproduction of VLDL, impacting triglyceride levels.

    Essential Fatty Acids and Prostaglandins

    • Essential fatty acids lead to the synthesis of prostaglandins containing 20 carbon atoms.

    Prostaglandin Structure

    • Active prostaglandins must have at least one double bond within specified positions in their carbon chain.

    Plasma Total Phospholipids Range

    • The normal plasma total phospholipid range is between 1.8 and 5.8 mmol/L.

    HDL2 Density

    • HDL2 exhibits a density range of 1.032-1.063, indicating its role in lipid transport.

    β-Lipoproteins Density

    • β-lipoproteins are characterized by a density range of 0.95-1.006, highlighting their functionality in lipid metabolism.

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    Description

    This quiz focuses on the role of phospholipids in cell membranes and the composition of fats and waxes. Each question tests your understanding of the importance of different components in biological structures. Test your knowledge on lipids and their functions!

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