In order to detect a signal (that is, to be a target cell), a neighbor cell must have the right receptor for that signal. When a signaling molecule binds to its receptor, it alters the shape or activity of the receptor, triggering a change inside of the cell. Signaling molecules are often called ligands, a general term for molecules that bind specifically to other molecules (such as receptors).
A chunk paragraph is just a way of developing your skill in writing - it is a style or format which forces you to explain your ideas and arguments. Here's you do chunk writing: Write your topic sentence.
The MERGE syntax consists of five primary clauses: 1  The MERGE clause specifies the table or view that is the target of the insert, update, or delete operations. 2  The USING clause specifies the data source being joined with the target. 3  The ON clause specifies the join conditions that determine where the target and source match.