Lipids and Membranes Flashcards

Which type of fatty acid contains one double bond?

Answer: Monounsaturated fatty acid

Monounsaturated fatty acids contain exactly one carbon-carbon double bond, such as oleic acid (18:1, Δ9), and are liquid at room temperature.

The fluid mosaic model of the cell membrane was proposed by:

Answer: Singer and Nicolson

Singer and Nicolson (1972) proposed the fluid mosaic model, describing the membrane as a dynamic lipid bilayer with embedded proteins that can move laterally.

Which lipid class forms the structural backbone of the cell membrane bilayer?

Answer: Phospholipids

Phospholipids are amphipathic molecules with a hydrophilic phosphate head group and hydrophobic fatty acid tails that spontaneously form bilayers in aqueous environments.

Cholesterol in animal cell membranes functions to:

Answer: Modulate membrane fluidity

Cholesterol inserts between phospholipid tails, reducing fluidity at high temperatures and preventing crystallization at low temperatures, thereby buffering membrane fluidity.

Eicosanoids (prostaglandins, thromboxanes, leukotrienes) are derived from which fatty acid precursor?

Answer: Arachidonic acid (20:4)

Arachidonic acid (20:4, ω-6) is released from membrane phospholipids by phospholipase A2 and serves as the substrate for cyclooxygenases and lipoxygenases to produce eicosanoids.

What is the term for the movement of a phospholipid from one leaflet of the bilayer to the other?

Answer: Flip-flop (transverse diffusion)

Flip-flop (transverse diffusion) is the movement of a lipid across the bilayer, which is thermodynamically unfavorable and requires flippase enzymes to occur rapidly.