If the insulin concentration rises fivefold to 2.5 × 10⁻¹¹ M, as it does after a meal, and the Kd for binding of insulin to its receptor on liver cells, 1.4 × 10⁻¹⁰ M (0.14 nM). What fraction of insulin receptors with bound insulin? 

TLS Online TPP Program

#Question id: 20333

#Unit 4. Cell Communication and Cell Signaling

Choose true statements about Ax21-mediated quorum sensing;

a. It is a highly conserved sulfated peptide secreted by Xanthomonas oryzae.

b. Ax21 is sulfated by RaxST, which is a putative tyrosine sulfotransferase.

c. Sulfated Ax21 is secreted via the RaxABC type I secretion system

d. Sulfated Ax21 secreted is recognized by the rice XA21 receptor.

TLS Online TPP Program

#Question id: 20334

#Unit 4. Cell Communication and Cell Signaling

Sulfotransferases are the first enzymes of the core sulfation pathways, they transfer sulfate from PAPS to the hydroxyl or amino group of a wide variety of acceptors, as given below

a. Molecular basis of symbiotic host specificity in Rhizobium meliloti: nodH and nodPQ genes encode the sulfation of lipochito-oligosaccharide signals

b. Sulfation of the choriogonadotropin alpha subunit in human placental explants

c. Tyrosine sulfation of the amino terminus of CCR5 facilitates HIV-1 entry

d. A tyrosine-sulfated peptide based on the N terminus of CCR5 interacts with a CD4-enhanced epitope of the HIV-1 gp120 envelope glycoprotein and inhibits HIV-1 entry.

e. The Xanthomonas oryzae pv. oryzae raxP and raxQ genes encode an ATP sulfurylase and APS kinase that are required for AvrXa21 avirulence.

Which one of the following combination of above statements is correct?

TLS Online TPP Program

#Question id: 20335

#Unit 4. Cell Communication and Cell Signaling

Quorum sensing-mediates the social cooperation and conflict both-

TLS Online TPP Program

#Question id: 1080

#Unit 4. Cell Communication and Cell Signaling

 In the formation of biofilms, such as those forming on unbrushed teeth, cell signaling serves which function?

TLS Online TPP Program

#Question id: 1081

#Unit 4. Cell Communication and Cell Signaling

Which of the following is a type of local signaling in which a cell secretes a signal molecule that affects neighboring cells?

TLS Online TPP Program

#Question id: 1082

#Unit 4. Cell Communication and Cell Signaling

Which of the following is a type of signaling in which a cells respond to substrate that they themselves release ?