ABSTRACT
SI units (Système International d’Unités) are the preferred units used in chemistry and biochemistry. The relevant ones in biochemistry are shown in Table 2.1.
In biochemistry, it is more acceptable to be a bit more clear and descriptive than to be too strict about definitions and symbols. It is perfectly all right to write mole or sec (instead of the SI symbols mol or s) and even use calories (cal) in calculations (for amount of heat energy). We do have some units that are used in biochemistry in conjunction with those in Table 2.1 and are likely to be retained because of their convenience. There are a number of units that are used in biochemistry that relate to water (like °C and calories). However, the current trend is to go all the way using SI units. (A full set of units and their conversions that may be of interest to biochemistry students is given in Appendix 1.)
When submitting research papers for publications, authors are strictly required to follow the “Instructions to Authors” provided by the editors of the journals. Unfortunately, each journal has different requirements, and there are local (or country) preferences. For example, M is tending to be reserved for the prefix “mega” (see Table 2.2) and not for “molar” (as it was used until quite recently); however, most biochemistry journals still permit its use for “molar.” Both upper case L and lower case l are also permitted for litres by most journals. Gallons, pints, and fluid ounces are still used in many advanced countries, although all use SI units in international science journals. Students should endeavour to be able to convert quantitative information into units and measures, and even utensils that ordinary folks use-for example, knowing how to dilute a herbicide for farm use, knowing the volume of a household bucket, and being aware that the volume contained in a teaspoon is 5 mL (hence liquid pharmaceuticals concentrations are often expressed in amount per 5 mL).
