Mechanism of ligation for both T4 DNA ligase and E. coli DNA ligase makes use of Adenosine Monophosphate (AMP). Which of the steps is involved in the ligation mechanism?

TLS Online TPP Program

#Question id: 14739

#Unit 4. Cell Communication and Cell Signaling

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: 14740

#Unit 4. Cell Communication and Cell Signaling

Rod cells sense light with the aid of a light-sensitive GPCR known as rhodopsin; choose incorrect statements

a. Rhodopsin consists of the protein opsin, which has the usual seven–transmembrane segment GPCR structure, covalently linked to a light-absorbing pigment called retinal. 

b. Rhodopsin, found only in rod cells, is localized to the thousand or so flattened membrane disks that make up the inner segment of each of these rod-shaped cells.

c. A human rod cell contains about 4 × 10⁷ molecules of rhodopsin. 

d. The heterotrimeric G protein coupled to rhodopsin, called transducin (Gt), contains a Gα unit referred to as Gαt; like rhodopsin, Gαt is found only in rod cells.

TLS Online TPP Program

#Question id: 14805

#Unit 4. Cell Communication and Cell Signaling

Secondary immune response to a hapten depends on the: 

TLS Online TPP Program

#Question id: 14806

#Unit 4. Cell Communication and Cell Signaling

Which is more immunogenic compound ?

TLS Online TPP Program

#Question id: 14807

#Unit 4. Cell Communication and Cell Signaling

For the stimulation of B-cell responses, lipids are used as haptens and attached to suitable carrier molecules such as the proteins keyhole limpet hemocyanin (KLH) or bovine serum albumin (BSA). If lipid plus KLH introduce in human body and activate immune system, after one month lipid and KLH injected in same person separately, antibody raised against?

TLS Online TPP Program

#Question id: 14808

#Unit 4. Cell Communication and Cell Signaling

Which of the following statements is true ?