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.
If you look at the piano keyboard, you'll see these 12 notes (not including the C on the right) being repeated over and over again, in the same configuration. These represent the notes in any musical scale (12 consecutive semi-tones). The white keys are natural notes (i.e. non sharps or flats). The black keys are the sharps and flats. In music notation, the sharp notes are designated by a #, whereas the flat notes are designated by a b (see diagram below). When you look at sheet music, it looks something like this.