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#cell membrane structure

3 public questions tagged with this topic.

Properties of Plasma Membrane

Which phospholipid is conical in shape and contributes to membrane curvature?

Intrinsic lipid curvature concept explains membrane remodeling during endocytosis exocytosis and organelle shaping. Lipid shape analyzed via Israelachvili packing parameter p equals v over a times l where v volume tail a head area l length: cylindrical p approximately one forms flat bilayers as phosphatidylcholine with two acyl chains head size similar to tail cross-section; conical p greater than one small head large tails such as phosphatidylethanolamine and diacylglycerol tends negative curvature monolayers bending toward water favoring inverted hexagonal HII phase; inverted conical p less

Ref: McMahon and Gallop, Membrane Curvature and PE Conical Shape, Nature 2005.

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Properties of Plasma Membrane

Which of the following lipids contributes to membrane thickness?

Membrane thickness determined by fatty acyl chain length unsaturation and sterol content influencing hydrophobic matching with integral protein transmembrane domains. Cholesterol small amphipathic sterol twenty seven carbons rigid tetracyclic ring structure with hydroxyl head and iso-octyl tail approximately one point five nanometer length intercalates among phospholipid acyl chains hydroxyl near glycerol carbonyl ester oxygen forming hydrogen bond, rigid rings restricting chain trans-gauche isomerization increasing order parameter measured by deuterium NMR and electron spin resonance, condens

Ref: de Meyer and Smit, Cholesterol Effect on Bilayer Thickness and Order, PNAS 2009.

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Lipids

Which of the following is not a major function of cholesterol?

Direct energy source is the correct choice because it does not accurately describe or belong to the category addressed in this question. In the context of Lipids without annotations, the other options (Precursor of steroid hormones, Component of plasma membranes, and Precursor for bile acids) are all valid and well-established concepts. Direct energy source is either unrelated to the topic, describes a different biological process, or represents a common misconception. Questions framed as 'which is NOT' require students to identify the exception among otherwise correct statements, demanding co

Ref: Lehninger Principles of Biochemistry, Nelson & Cox, 8th Ed., Ch. 10

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