Clearly these chapters contain a number of highly significant quotes. What I suggest you do is think of the main themes of the novel an then re-read these chapters to establish which quotes can be used to support or tie in to these themes. Let me give you an example. One of the biggest themes of the novel is the way in which Victor uncovers forbidden knowledge and feels driven to keep on pursuing that forbidden knowledge to its terrifying conclusion. If we examine Chapter Four, we see he makes an important breakthrough:
When I found so astonishing a power placed within my hands, I hesitated a long time concerning the manner in which I should employ it. Although I possessed the capacity of bestowing animation, yet to prepare a frame for the reception of it, with all its intricacies of fibres, muscles, and veins, still remained a work of inconceivable difficulty and labour. I doubted at first whether I should attempt the creation of a being like myself, or one of simpler organisation; but my imagination was too much exalted by my first success to permit me to doubt of my ability to give life to an animal as complex and wonderful as man.
Note the way in which Victor discovers the scientific method in which "animation" or life could be given to a corpse or body. Even though he recognises what a significant achievement he has made, this is still not enough. Consider the lst sentence in this quote and the way in which his "imagination was too exalted" to give him any room for doubt. Victor is set on his course of making a human and giving him life, and his pride, imagination and focus is based on this alone. He is set on not only uncovering forbidden knowledge, but going one step further and playing God himself.