Cellular biology studies the structure and functions of the many different things inside a cell.

Molecular biology looks into the insides of cells and studies how the different systems work with each other on a molecular basis. e.g., DNA, RNA, amino acids, and the creation of proteins, how they interact with each other, and what affects these interactions.

Structural biology looks at the shape of biological molecules like amino acids, nucleic acids, and enzymes; why they have those structures, and how differences in their structure affect how they work

biochemistry looks at how these biological molecules interact with each other on a chemical level. biochemistry studies the underlying chemical signals and reactions of life.

biophysics and quantum biology: techniques in physics like x-ray crystallography or cryo-electron microscopy are used to see the structure of biomolecules. They also look at the physics that underpins biological processes seeking to explain how things work on a physical level.

genetics is the study of how DNA is expressed to create all of the different forms of life through genes, and how this information is passed on through generations.

population genetics looks at the genetic differences within a species and how species differ from one another.

bioinformatics uses computer programming to analyze and interpret biological data in genetics, and also many other fields wherever the amount of data is too large to analyze with previous statistical methods.

biomathematics uses the tools of mathematics to build models of biological processes and is used in many different areas from genetics to biotechnology to studying ecosystems.