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TLS Online TPP Program

#Question id: 2838

You want to study the potential interaction between nucleosome-bound DNA and a specific histone deacetylase. You decide to perform an electrophoretic mobility shift assay (EMSA). You use a 32P end-labelled, linear template DNA that contains two nucleosome positioning sites. You assemble two nucleosomes on the DNA template before incubation with and without the histone deacetylase. For some reactions, you use unmodified nucleosomes. For other reactions, you use nucleosomes that are methylated at lysine 36 of the histone protein H3.

A. The histone deacetylase binds nucleosome bound-DNA in lanes 1, 2, 3, and 4.

B. The histone deacetylase binds nucleosome bound-DNA in lanes 3& 4.

C. The histone deacetylase seems to recognize methylated nucleosomes at lysine 36 of histone H3 in lane 1, 2 & 3 better than unmethylated nucleosomes in lane 4 &5

D. The histone deacetylase seems to recognize methylated nucleosomes at lysine 36 of histone H3 in lane 1 & 2 better than unmethylated nucleosomes in lane 3 &4

#Unit 2. Cellular Organization

  1. A, B & C only

  2. A& B only       

  3.  A& D only  

  4.  D only

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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
TLS Online TPP Program

#Question id: 33362

#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 have changed pI as compared to HbA
TLS Online TPP Program

#Question id: 33363

#Unit 1. Molecules and their Interaction Relevant to Biology

An antibody binds to an antigen with a Kd of 5 X10-8 M. At what concentration of antigen will θ be 0.2