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TLS Online TPP Program

#Question id: 2179

Ion channels achieve selectivity in transport through all of the following mechanisms EXCEPT:

#Unit 2. Cellular Organization

  1. evolution from distinct and different parent proteins.

  2. divergent evolution from a single type of channel protein.

  3. low activation energy for selective passage of the dehydrated ion.

  4. use of P segments to form an ion selectivity filter.

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TLS Online TPP Program

#Question id: 33356

#Unit 1. Molecules and their Interaction Relevant to Biology

Hemoglobin undergoes substantial changes in quaternary structure on oxygen binding: the a1b1 and a2b2 dimers rotate with respect to each other by
TLS Online TPP Program

#Question id: 33357

#Unit 1. Molecules and their Interaction Relevant to Biology

Protein A has a binding site for ligand X with a Kd of 10-6 µM. Protein B has a binding site for ligand X with a Kd of 10-9 µM. Which statement is incorrect?
TLS Online TPP Program

#Question id: 33358

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following situations would produce a Hill plot with n<  1.0?
(a) The protein has multiple subunits, each with a single ligand-binding site. Binding of ligand to one site decreases the binding affinity of other sites for the ligand.
(b) The protein is a single polypeptide with two ligand-binding sites, each having a different affinity for the ligand.
(c) The protein is a single polypeptide with a single ligand-binding site.
TLS Online TPP Program

#Question id: 33359

#Unit 1. Molecules and their Interaction Relevant to Biology

The protein calcineurin binds to the protein calmodulin with an association rate of 8.9 X103 M-1s-1 and an overall dissociation constant, Kd, of 10 nM. The dissociation rate, kd
TLS Online TPP Program

#Question id: 33360

#Unit 1. Molecules and their Interaction Relevant to Biology

a. HbS (sickle-cell Hb): substitutes a Val for a Glu on the surface
b. Hb Cowtown: eliminates an ion pair involved in T-state stabilization
c. Hb Memphis: substitutes one uncharged polar residue for another of similar size on the surface
d. Hb Bibba: substitutes a Pro for a Leu involved in an α helix

Which Hb variant least likely to cause pathological symptoms
TLS Online TPP Program

#Question id: 33361

#Unit 1. Molecules and their Interaction Relevant to Biology

a. Hb Cowtown: eliminates an ion pair involved in T-state stabilization
b. Hb Milwaukee: substitutes a Glu for a Val
c. Hb Providence: substitutes an Asn for a Lys that normally projects into the central cavity of the tetramer
d. Hb Philly: substitutes a Phe for a Tyr,

Which Hb variant will not bind to BPG