What is biochemistry, and how does it differ from the fields of genetics, biology, chemistry, and molecular biology?

Biochemistry is the study of chemicals within organisms, and an amalgam of the other sciences to be mentioned in this post. Using bits and pieces of genetics, biology, chemistry and molecular biology to describe the chemicals within organisms and their function within that organism. Genetics is the study of DNA and gene expression in organisms, focusing both on the genotypic expression (microscopic level) and the phenotypic expression (macroscopic level) of genetic traits. Biology is the study of organisms (on a macro scale mostly) and their interactions with other organisms. Molecular biology focuses on the molecular processes that occur within cells, it is very closely related to biochemistry.