Too often we overlook the tough job that tRNAs do, seeing them only as the handmaidens of translation: matching up with mRNA; delivering a specific amino acid place on their heads by synthetases, arriving at the ribosome to first take the chain and then be stripped of it… These tiny (~100 nte.) elves perform a series of amazing sleights-of-hand: sometimes they must all be the same (the ribosome must deal similarly with all of them); at other times, unique (codon matching) and still other times, as ‘family members’ (all those ‘serviced’ by a single tRNA synthetase. Just how much recognition-surface and information is stamped onto a tRNA?
‘What to teach’ in Introductory Biology presents a whole host of conundrums. Is our role to cover the breadth of all of biology (or all of the biology student will hear again in upper divisions) at breakneck pace and without depth? A whirlwind tour of vocabulary to commit to memory with vague understanding for some later date? I will argue periodically that we should pick a limited, integrated fraction of possible content and teach it in a way that allows students to see and grasp underlying concepts and universal themes, thereby enabling them to figure out what comes later, and to embark on their own to investigate whatever catches their fancy.
The key ideas of biology’s Central Dogma–or better put, the flow of information— are a critical case in point. We all agree that ‘something’ about DNA, RNA and protein is among our core duties. But what? My view is that identifying the roles of each of these players, how their structures fit them to play those roles, how they came to occupy and the ‘flow’ between them them are straightforward, core ideas in biology.
I think we’re focusing on the wrong thing when we follow classical textbook approaches to ‘Biomolecules’ and their categories (DNA, RNA, protein, carbs, lipids). I don’t have much to say about the latter two, but there are some Big Ideas about the molecules of the central dogma that I believe get lost in the tedium of -OH groups and dehydration reactions… I’ll discuss order of presentation and such later; now I want to talk about monomer structure. To wit: How are (the group nucleic acid monomers) and (the group amino acids) all similar, and why must this be so?