All organisms make food either through photosynthesis or Chemosynthesis
.In this case bacteria are creating sugar (food) through all the course of activities mentioned here. Bacteria that live deep under the ocean uses energy released by any chemical reaction to make food (sugar) for themselves.
The chemical reaction involved here is as follows -
There are histones in the nucleus that DNA coils around. The part of the DNA that is coiled around the histones is not accessible, and cannot be expressed in that cell. DNA that is not wrapped around a histone can be transcribed.