A whole comprises its parts:

• “12 different enzymes comprise the system.” WRONG
• “The system comprises 12 different enzymes.” RIGHT

while the parts constitute the whole:

• “The system constitutes 12 different enzymes.” WRONG
• “12 different enzymes constitute the system.” RIGHT

The word compose is often used in place of comprise, though like constitute, the parts compose the whole, not visa versa. But by using the “is composed of” construction, the roles of the subject and object are reversed:

• “The system is composed of 12 different enzymes.” RIGHT

In my experience, this idiom is more common, especially in spoken English; probably due to the confusion about the proper use of comprise.

[Edit: due to broken CSS, wrong sentences were not properly marked wrong. Fixed.]

Here’s a little levity for a Monday morning: the authors of “Learn Your Damn Homophones” are a little angry about the misuse of homophones (words that are pronounced identically but spelled differently). Okay, incredibly angry. But the advice they give is good, and it’s a good and funny read, provided you don’t mind abundant cuss words and barely controlled rage:

http://www.learnyourdamnhomophones.com/

An abbreviation is any shortened form of a word or phrase: “HEPES,” “Ph.D.,” “etc.,” etc.

Initialisms comprise a subset of abbreviations where the first letter of each word (more or less) of a phrase are combined. Some examples include the “Food and Drug Administration” = “FDA,” “adenosine di-phosphate” = “ADP”, and “4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid” = “HEPES.”

In physical science manuscripts, nearly all initialisms should be written in all capital letters without spaces or periods. (There are some exceptions, such as “a.m.,” “r.m.s.d.,” etc.) This is certainly the case if you introduce new initialisms for brevity or clarity. When introducing an initialism, write it out first, followed by the abbrevation in parentheses: e.g. “structural genomics (SG).” Don’t underline or otherwise highlight the letters used in the initialism.* Don’t introduce new or uncommon initialisms unless you will be using the term several times.

Technically, not all initialisms are acronyms, even though in common spoken English the terms are largely used interchangeably. Acronyms comprise the subset of initialisms that are pronounced as a word rather than a spelled list of letters. For example, “AIDS” and “laser” are acronyms, while “ADP” and “NIH” are initialisms.

* Yes, I know I did that in the prior paragraph. Hey! What’s that over there! <runs away>

The field of bioinformatics, namely the use of computing to collect and analyze biological and biochemical information, is exploding in popularity. The word itself, however, is new. The noun “bioinformatics” was coined by researchers Paulien Hogeweg and Ben Hesper in 1978. According to the Merriam Webster dictionary, it is a special kind of collective noun that is plural but singular in construction. This means that it refers to a group of computational techniques, the group itself is treated as a singular subject:

• “Bioinformatics are the study of…” WRONG
• “Bioinformatics is the study of…” RIGHT

There is some debate as to how “bioinformatics” should be used as an adjective. In English, some nouns may be used to modify other nouns in the same way as an adjective:

• “I studied biology in school.” (noun)
• “I used a biology textbook in my classes.” (noun modifier)

However, many nouns also have adjective forms, which are preferred in most contexts. For example, the adjective form of “biology” is “biological":

• “I did a biology analysis.” (noun modifier)
• “I did a biological analysis.” (adjective)

While the former is grammatically correct, to my ear the latter sounds more natural and idiomatic. For the noun “bioinformatics,” the Merriam Webster dictionary identifies “bioinformatic” as the adjective form:

• “I did a bioinformatics analysis.” (noun modifier)
• “I did a bioinformatic analysis.” (adjective)

Like the previous example, while I can’t definitively say that the former (noun modifier) form is grammatically incorrect, I prefer the adjective form “bioinformatic” when an adjective is called for.