Subject: Exactly how is caffeine produced in a plant, like the cacao bean?

This question is in relation to my science fair project. It is on how caffeine 
affects the growth and development of a plant. I feel I cannot form a decent 
hypothesis for this question without knowing at first how it is that caffeine 
is produced naturally in some plants. I have already read and re-read all 
questions and answers relating to caffeine and plants on this website, and 
have used some of that information. However, in none of the answers is it said 
EXACTLY how (on the molecular level perhaps) caffeine is produced in a plant, 
and I'd really appreciate an answer to that question.

Re: Exactly how is caffeine produced in a plant, like the cacao bean?