#Question id: 1705
#Unit 4. Cell Communication and Cell Signaling
What is the single best definition of the most common form of antigen recognized by the T-cell receptor (TCR)
#Question id: 7218
#Unit 5. Developmental Biology
Following statements are regarding to convergent extension of the dorsal mesoderm in xenopus.
A. For convergent extension the first force is a polarized cell cohesion wherein the involuted mesodermal cells intercalate and the second force is differential cell cohesion.
B. The intercalations of mesodermal cells, both mediolaterally and radially, are stabilized by the planar cell polarity (PCP) pathway that is initiated by Wnts independent of β-catenin signaling.
C. The intercalations of mesodermal cells, are stabilized by the planar cell polarity (PCP) pathway that is initiated by Wnts dependent of β-catenin signaling.
D. Another factor regulating convergent extension is calcium influx from environment.
E. Ca2+ is released from intracellular stores and is required for convergent extension.
Which of the following combination is correct?
#Question id: 1323
#Unit 4. Cell Communication and Cell Signaling
Which of the following proteins forms channels that permit electrical communication between cells across gap junctions?
#Question id: 1374
#Unit 4. Cell Communication and Cell Signaling
Following statements are regarding to gap junctions.
i. Vertebrate gap junctions are composed of connexins, a family of structurally related transmembrane proteins with molecular weights between 26,000 and 60,000.
ii. Each vertebrate hexagonal particle consists of six noncovalently associated connexin molecules. Each individual connexin molecule has two membrane-spanning α helices with a topology similar to that of claudin.
iii. The permeability of gap junctions is regulated by posttranslational modification of connexins (e.g., phosphorylation) and is sensitive to changes in environmental conditions
such as intracellular pH and Ca2+ concentration, membrane potential, and the intercellular potential between adjacent interconnected cells (“voltage gating”).
iv. The assembly of connexins, their trafficking within cells, and the formation of functional gap junctions apparently depend on N-cadherin and its associated adapter proteins as well as desmosomal proteins.
Which of the following statements are correct?
#Question id: 23784
#Unit 7. System Physiology – Animal