In heart muscle, activation series of the muscarinic acetylcholine receptor its effector K+ channel via the Gβγ subunit of a Gi protein.

a. Binding of acetylcholine triggers activation of the Gαi subunit and its dissociation from the Gβγ subunit in the usual way. 

b. The released Gβγ subunit (rather than Gαi∙GTP) binds to and opens the associated effector protein, a K+ channel. 

b. The increase in K+ permeability hyperpolarizes the membrane, which reduces the frequency of heart muscle contraction. 

d. Activation is terminated when the GTP bound to Gαi is hydrolyzed (by a GAP enzyme that is an intrinsic part of the Gαi subunit) to GDP and Gαi∙GDP recombines with Gβγ.

TLS Online TPP Program

#Question id: 27418

#Unit 1. Molecules and their Interaction Relevant to Biology

Inner monolayer of trans Golgi network is made up of

TLS Online TPP Program

#Question id: 27419

#Unit 1. Molecules and their Interaction Relevant to Biology

The distribution of lipids in the membranes of a typical cell Each membrane has its own characteristic composition, and the two monolayers of a given membrane may differ in composition hence choose which of the following is incorrect 

Note = OML = outer mono layer, IML = inner mono layer

TLS Online TPP Program

#Question id: 27420

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following membrane do not have cholesterol

1.Plasma membrane (E. coli)

2.Outer mitochondrial membrane (cauliflower)

3.Inner mitochondrial membrane (cauliflower)

4.Chloroplast inner membrane

TLS Online TPP Program

#Question id: 27421

#Unit 1. Molecules and their Interaction Relevant to Biology

Highest concentration of cholesterol are found in

TLS Online TPP Program

#Question id: 27422

#Unit 1. Molecules and their Interaction Relevant to Biology

There are two extreme states of bilayer lipids choose which of the following is correct  

1.In the liquid- ordered (Lo) state, polar head groups are non uniformly arrayed at the surface, and the acyl chains are nearly motionless and packed with irregular

2.in the liquid- ordered (Lo) state, polar head groups are uniformly arrayed at the surface, and the acyl chains are nearly motionless and packed with regular

3.In the liquid-disordered (Ld) state acyl chains undergo much thermal motion and have regular organization.

4.In the liquid-disordered (Ld) state, acyl chains undergo much thermal motion and have no regular organization.

TLS Online TPP Program

#Question id: 27423

#Unit 1. Molecules and their Interaction Relevant to Biology

Cholesterol Poor region are maintained in the