BIOC440 Autumn Quarter
Review of Units
Biochemistry is a quantitative science, which means that using proper units is important.
You should have learned about units and how to convert among them in Introductory
Chemistry, but you may not have used them in awhile. Many of the problems you will
be learning to solve in this course will require use of units, so you should review and re-
memorize the fundamental concepts, such as:
1. Moles (“mol”) are NOT the same as Molar (“M”). The first is a count of the number of
things you have, and the latter is a concentration, i.e., the number of things you have
per unit of volume, in this case, mol/L. Using these two units interchangeably is just
plain wrong, and will be counted as such on exams.
2. Biochemistry takes place in dilute solution; i.e., most of the concentrations we care
about are much lower than 1 M. Therefore, we tend to report concentrations in units of:
mM = millimolar = 10-3 M
mM = micromolar = 10-6 M = 10-3 mM
nM = nanomolar = 10-9 M
pM = pico molar = 10-12 M
Similarly, volumes often tend to be small:
mL = milliliter = 10-3 L
mM = microliter = 10-6 L = 10-3 mL