Question

Which of the following is a fundamental characteristic of the Notch pathway?

A) It works through nuclear signals involving the lac operon.
B) It works through direct cell to cell contact.
C) It allows mRNAs to accumulate in the posterior portion of the Drosophila embryo.
D) It directs mRNAs to antisense systems in the posterior portion of all organisms.
E) It provides symmetry to plant flowers.

Answer 1

The Notch pathway is characterized by its requirement for direct cell-to-cell contact for signaling, where the Notch receptor binds to a ligand on an adjacent cell, triggering a series of intracellular events that affect gene expression.

Step-by-step explanation:

The Notch pathway is a fundamental cell signaling system that is crucial for many aspects of cell differentiation, tissue development, and organismal life. One of the hallmarks of the Notch signaling pathway is that it relies on direct cell-to-cell contact for communication. Unlike some other signaling systems that can involve endocrine or paracrine signaling, where molecules are secreted and diffuse to other locations, the Notch pathway requires a physical, direct interaction between neighboring cells. This happens when a Notch receptor on one cell binds to a ligand present on an adjacent cell. Upon ligand binding, the Notch receptor undergoes proteolytic cleavage; its intracellular domain (NICD) is released into the cytoplasm and translocates to the nucleus, where it influences gene expression and subsequent cell fate decisions. Therefore, the correct answer to the question is B) It works through direct cell to cell contact.