Which of the following is true for the unwinding of the DNA helix and the synthesis of a short stretch of RNA?

#Question id: 1362

#Unit 4. Cell Communication and Cell Signaling

That cancer cells often lack the gap junctions common to non-malignant cells of the same type is evidence that

#Question id: 1363

#Unit 4. Cell Communication and Cell Signaling

Which of the following statements best describes the difference between low-affinity integrins and high-affinity integrins?

#Question id: 1364

#Unit 4. Cell Communication and Cell Signaling

In mice engineered to overexpress the syndecan-1 gene in the hypothalamic region of the brain and other tissues, normal control of feeding by antisatiety peptides is disrupted, and the animals overeat and become obese. Other studies have shown that syndecan-3 may also be involved in the regulation of feeding behavior. Given the following information, which of these outcomes might you expect in experimentally manipulated mice?

I. Hypothalmic expression of syndecan-3 is increased by fasting.

II. Syndecan-3 knockout mice are resistant to diet-induced obesity.

III. Heparinase can cleave syndecan-3 to release heparin sulfate GAG chains that may suppress the activity of antisatiety peptides and feeding behavior.

Following statements are:

A. Overexpression of heparinase in mice with normal levels of syndecan-3 would result in resistance to diet-induced obesity.

B.  In mice with normal levels of syndecan-3, fasting followed by free access to a high-fat diet would lead to resistance to diet-induced obesity.

C. Lack of heparinase in mice with normal levels of syndecan-3 would result in animals that overeat and become obese.

D. Overexpression of heparinase in syndecan-3 knockout mice would reverse the resistance to diet-induced obesity.

Which of the following combination is correct?

#Question id: 1365

#Unit 4. Cell Communication and Cell Signaling

Which of the following best describes the structure of integrins?

#Question id: 1366

#Unit 4. Cell Communication and Cell Signaling

Mechano-transduction is the reciprocal interconversion of a mechanical force—or stimulus—and biochemical processes. These interconversions underlie a variety of biological activities, such as signaling, regulated gene expression, cell proliferation, cell migration, and interactions among cells and between cells and the ECM. Mechano-transduction in the context of cell-cell and cell-ECM interactions usually involves a cell-surface CAM or adhesion receptor that transmits mechanical force or biochemical information across the plasma membrane and one or more intracellular or extracellular mechano-sensors that respond to the mechanical stimulus by changing shape and activity. In Hypothetical model of the partial unfolding of a fibronectin type III, when that protein is subjected to mechanical force, following observations are-

A. Mechanical force generated within the cell by actin movement and transduce via multiple integrin adhesion receptors bound to the extracellular dimeric fibronectin can partially unfold the fibronectin.

B. The unfolding is thought to expose a putative, previously hidden binding site on fibronectin that has the potential to form β sheets with other fibronectin molecules, recruiting them to form fibronectin fibrils, and thus helping assemble the ECM.

According to observations which of the following protein act as mechano-sensor and mechano-transducer respectively?

#Question id: 1367

#Unit 4. Cell Communication and Cell Signaling

Match the following junctions (column A) with their intracellular adaptors (column B).