Cell-to-cell communication (gap junctions, plasmodesmata) Original Scenario-Based Practice

Questions

1. 1.

   In an advanced bioengineering laboratory, researchers design a synthetic tissue graft combining wall-less mammalian cardiac cells with rigid, wall-bearing plant cells to study direct intercellular transport. When comparing the direct cytoplasmic bridges connecting adjacent plant cells to the channel complexes connecting adjacent animal cells, the team analyzes their ultrastructure and membrane relationships. Which statement accurately distinguishes the plant cell channels (plasmodesmata) from the animal cell channels (gap junctions)?

   • A) Plasmodesmata traverse rigid cell walls and contain a central strand of modified endoplasmic reticulum called a desmotubule, whereas gap junctions consist of transmembrane protein complexes that directly bridge adjacent animal plasma membranes without penetrating a cell wall.
   • B) Plasmodesmata are composed of cylindrical connexon protein rings that maintain an open pore between bare membranes, whereas gap junctions penetrate thick extracellular cellulosic walls via shared outer membranes.
   • C) Plasmodesmata completely isolate the cytoplasm of neighboring cells to prevent viral transmission, whereas gap junctions fuse adjacent lipid bilayers into a continuous, non-selective channel capable of transporting intact organelles.
   • D) Plasmodesmata rely on exocytic vesicle release across a narrow synaptic cleft, whereas gap junctions provide direct cytoplasmic continuity solely through an extension of the Golgi apparatus.

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