2. In this chapter, you learned that some pathogens must attach to host cells to cause disease. To accomplish this, molecules on their surface (adhesins or ligands) recognize and attach to molecules (receptors or integrins) on the surface on certain host cells.
So a chromatic note, is any note you play that is not in the scale you are playing. They are also a great way to practice, especially if you are going through the pentatonic scale. Try adding one of these outside chromatic notes to your scale, and see how it sounds above the chord you are playing over.
The chromatic harmonica is a type of harmonica that uses a mechanical apparatus to control which holes make noise. Basic chromatic harmonicas with 10 notes can only play one full key (the same as a diatonic harmonica), but chromatics with 12-16 holes can be tuned to any key.