Which of the following is true for the mechanism of excision repair?

#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).

#Question id: 1368

#Unit 4. Cell Communication and Cell Signaling

The following statements are made with reference to the characteristic of proteoglycans (major constituents of ECM). Which one of them is incorrect?

#Question id: 1369

#Unit 4. Cell Communication and Cell Signaling

The following statements are made with reference to characteristics of glycosaminoglycans and proteoglycans, which are major constituents of extracellular matrix. Which one of them is incorrect?

#Question id: 1370

#Unit 4. Cell Communication and Cell Signaling

H. V. Wilson worked with sponges to gain some insight into exactly what was responsible for holding adjacent cells together. He exposed two species of differently pigmented sponges to a chemical that disrupted intercellular junctions, and the cells of the sponges dissociated. Wilson then mixed the cells of the two species and removed the chemical that caused the cells to dissociate. Wilson found that the sponges reassembled into two separate species. The cells from one species did not interact or form associations with the cells of the other species.

How do you explain the results of Wilson's experiments?

#Question id: 1371

#Unit 4. Cell Communication and Cell Signaling

A researcher was studying a protein ‘A’ which has been observed to move across cells when an extracellular electrical stimulus is provided. An artificial peptide ‘Z’ was prepared which resembles the structure of pannexins and competitively inhibits pannexon formation. Which one of the following statements will best explain the fate of protein ‘A’ if, the cells are treated with peptide ‘Z’ and then, electrical stimulus is provided.