Complex sentence: The sequential passage will begin in the home key, and may move either diatonically or chromatically; harmonic function is generally disregarded in a sequence, or, at least, it is far less important than the sequential motion.
Split into simpler sentences: The sequential passage will begin in the home key, and may move either diatonically or chromatically. Harmonic function is generally disregarded in a sequence, or, at least, it is far less important than the sequential motion.