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.
Chunking certainly is not a cure-all for memory problems, but it can be an effective tool in your memory improvement arsenal. By practicing chunking methods regularly and incorporating this technique in your study habits, you might find that you are able to remember more. Bor, D. (2012).