Molecular and Cellular Biology
The cell is the unit of life. The body contains 37 trillion human cells, and almost ten times more non-human cells, such as bacteria and parasites. There are trillions of chemical reactions occurring each second inside each cell, and there is ongoing communication between all cells using molecules that they send and receive from the extracellular environment.
Molecules (Molecular Biology)
LDL (Low Density Lipoprotein)
PSA (prostate specific antigen)