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.
On a full scale piano, there are a total of 88 keys, but there are only twelve different notes which are repeated from low to high tones, from the base to the treble. In the illustration above you can see twelve tones that also make one octave and these notes also form a Chromatic Scale).