If you're using Python and don't use Django (I've tried it as an exercise for one of my pet projects), you have 2 options.

Create your own framework - writing http headers etc from scratch which will take you forever or Use a lightweight framework like Flask or Web.py.

Either way, you'll end up creating your own ways to query the database and creating patterns to communicate with frontend. As you write more code, you'll abstract your code to reusable methods.

About a month into the project, you'll realize that you're slowly rolling out your own framework which has grown organically.

Soon you'll realize you're better off using a polished framework like Django which has abstracted many of the details so you can focus on delivering value instead of clobbering together your own framework which will become a burden to maintain alongside your app.