The Weight of Grades

As the first quarter comes to a close, I have been thinking about my current grading system. In all my classes I weigh homework as 10%, classwork as 20%, quizzes as 30% and tests, projects and essays as 40%. I am not happy with this system. In my sophomore English class, if a student did not hand in his/her final essay on The Catcher in the Rye, they could not pass the class for the quarter. Considering we spent over a month on the novel and two entire class periods writing these essays, there really isn't too much of an excuse for not completing this. On the other hand, if a student read the novel, understood its themes and participated in class discussions, is it fair that they don't pass the class because they didn't write an essay? I have not made a decision on this yet, but I am considering switching to a total points grading system, with major projects and essays being worth more points than say, a regular homework assignment. Thoughts on this are welcome.