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#aquaporins

4 public questions tagged with this topic.

Membrane Transportation

Which of the following molecules moves most efficiently through aquaporins?

Aquaporins represent a family of tetrameric channel proteins mediating extremely rapid yet selective water transport essential for osmoregulation, kidney concentration and brain water balance. Each monomer contains six transmembrane helices plus two half helices HB and HE each bearing conserved Asn-Pro-Ala motif that meet centrally forming dipoles. Water moves single file through an hourglass pore constricted to 2.8 angstrom at aromatic arginine filter where histidine, arginine and phenylalanine side chains create size barrier. Permeation rate exceeds one billion molecules per second per monom

Ref: Agre et al., Nobel Lecture 2003, Aquaporin Water Channels Structure - NPA Motifs and Proton Exclusion.

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Membrane Transportation

What is the primary function of aquaporins?

Water homeostasis requires rapid equilibration across membranes due to filtration secretion challenges. Simple diffusion through lipid bilayer measurable permeability ten to minus three cm per second insufficient for tissues requiring high flux such as kidney proximal tubule collecting duct reabsorbing one eighty liters per day erythrocytes facing shear retinal epithelium astrocytes buffering potassium via swelling. Aquaporins form family of integral channels forming homotetramers where each monomer twenty eight kilodaltons six transmembrane helices two half helices conserved NPA motifs create

Ref: Agre, Nobel Lecture 2003: Aquaporins – Water Channel Discovery and Function.

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WATER TRANSPORT+PYQS

Aquaporins are involved in:

The right choice is C: Facilitated water transport. In WATER TRANSPORT, that matches how the process or concept actually works — the other choices mix up related ideas or use the wrong mechanism. Skip these: A) Ion transport; B) Sugar transport; D) Active pumping. A quick check: if an option needs energy, pumps, or the opposite direction of movement, ask whether that really applies.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

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