TLS Online TPP Program

#Question id: 2724


When DNA is compacted by histones into 10 nm and 30 nm fibers, the DNA is unable to interact with proteins required for gene expression. Therefore, to allow for these proteins to act, the chromatin must constantly alter its structure. Which processes contribute to this dynamic activity?

#Unit 2. Cellular Organization
  1. DNA supercoiling at or around H1

  2. Methylation and phosphorylation of histone tails

  3. Hydrolysis of DNA molecules where they are wrapped around the nucleosome core

  4. Accessibility of heterochromatin to phosphorylating enzymes

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TLS Online TPP Program

#Question id: 1259

#Unit 4. Cell Communication and Cell Signaling

Following statements are regarding to the phosphoinositide pathway.

A. many activated RTKs and cytokine receptors initiate phosphoinositide pathway by recruiting the enzyme phosphatidylinositol-3 kinase (PI-3 kinase) to the membrane.

B. PI-3 kinase adds a phosphate to the 3′ carbon in one of two separate phosphatidylinositol substrates, leading to formation of two phosphatidylinositol 3-phosphates: PI(3,4)P2 or I(3,4,5)P3

C. PI-3 kinase pathway can trigger cell division and prevent apoptosis, thus ensuring cell survival by the activation of PKB.

D. Activated PKB phosphorylates FOXO3a, which induces the expression of several antiapoptotic genes.

Which of the following combination is correct?

TLS Online TPP Program

#Question id: 1260

#Unit 4. Cell Communication and Cell Signaling

Which of the following statement regarding RTK/Ras pathway is incorrect?

TLS Online TPP Program

#Question id: 1261

#Unit 4. Cell Communication and Cell Signaling

A FOXO3a mutant in which the three serine residues that are targets for PKB are mutated to alanine then what will be the result?

TLS Online TPP Program

#Question id: 1262

#Unit 4. Cell Communication and Cell Signaling

Although MAP kinase is often activated in multicellular animals by RTKs or cytokine receptors, signaling from other receptors can activate MAP kinase in other eukaryotic cells. we consider the mating pathway in the yeast S. cerevisiae, a well-studied example of a MAP kinase cascade linked to G protein–coupled receptors (GPCRs). Which of the following statement is incorrect?

TLS Online TPP Program

#Question id: 1263

#Unit 4. Cell Communication and Cell Signaling

The major classes of CAMs include

a. cadherins.    b. fibronectin.    c. Ig-superfamily CAMs.      d. P-selectins.

TLS Online TPP Program

#Question id: 1264

#Unit 4. Cell Communication and Cell Signaling

 Desmosomes